EUROPEAN WHITE BOOK

EUROPEAN WHITE BOOKON F UNDAMENTAL R ESEARCHIN M ATERIALS S CIENCEM AX-PLANCK-INSTITUT FÜR M ETALLFORSCHUNG S TUTTGART

CONTENTS | PREFACE | EXECUTIVE SUMMARY | INTRODUCTION 41. MATERIALS: SCIENCE AND ENGINEERING 182. MATERIALS: SCIENCE AND APPLICATION 683. INNOVATION IN MATERIALS SCIENCE BYNEW INTERDISCIPLINARY APPROACHES 1144. MATERIALS THEORY AND MODELLING 1265. MATERIALS PHENOMENA 1506. MATERIALS SYNTHESIS AND PROCESSING 1947. ADVANCED ANALYSIS OF MATERIALS 2348. MATERIALS SCIENCE IN EUROPE 2689. MATERIALS SCIENCE AND BASIC RESEARCH IN EUROPE:CONCLUSIONS AND RECOMMENDATIONS 288APPENDICES I TO V 310

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART44810161921263237485155576367EUROPEAN WHITE BOOKON FUNDAMENTAL RESEARCH IN MATERIALS SCIENCEContentsPrefaceG. Wegner, Vice President, Max-Planck-Gesellschaft, München, GermanyExecutive SummaryM. Rühle, H. Dosch, E. Mittemeijer, M.H. Van de Voorde, Max-Planck-Institut für Metallforschung, Stuttgart, GermanyIntroductionM. Rühle, Max-Planck-Institut für Metallforschung, Stuttgart, Germany1. MATERIALS: SCIENCE AND ENGINEERINGIntroduction1.1. Metals and Composites: Basis for Growth, Safety, and EcologyD. Raabe, Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany1.2. Advanced Ceramic Materials: Basic Research ViewpointF. Aldinger, Max-Planck-Institut für Metallforschung, Stuttgart, GermanyJ.F. Baumard, ENSCI, Limoges, France1.3. Advanced Ceramic Materials: Summary of Possible ApplicationsG. Fantozzi, D. Rouby, J. Chevalier, P. Reynaud, GEMPPM, INSA de LYON, Lyon, France1.4. Inorganic MaterialsJ. Etourneau, I.C.M.C.B., Université de Bourdeaux, Pessac, France1.5. Soft Materials and Polymers: The Rise and Decline of Polymer Science & Technology in EuropeP. Lemstra, Faculteit Scheikundige Technologie, Technische Universiteit Eindhoven, The Netherlands1.6. Soft Materials and Polymers: Strategies for Future Areas of Basic Materials ScienceG. Wegner, Max-Planck-Institut für Polymerforschung, Mainz, Germany1.7. Carbon MaterialsR. Schlögl, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, GermanyP. Scharff, Institut für Physik, Technische Universität Ilmenau, Thüringen, Germany1.8. Electronic and Photonic MaterialsA.Trampert and K.H. Ploog, Paul-Drude-Institut für Festkörperelektronik, Berlin, Germany1.9. Nanotechnology and Semiconducting MaterialsM. Lannoo, ISEM, Maison des Technologies, Toulon, FranceConclusions6970727678822. MATERIALS: SCIENCE AND APPLICATIONIntroduction2.1. Biomaterials: EvolutionN. Nakabayashi and Y. Iwasaki, Tokyo Medical and Dental University, Kanda, Tokyo, Japan2.2. Biomaterials: Research and DevelopmentW. Bonfield, Department of Materials Science & Metallurgy, University of Cambridge, Cambridge, United Kingdom2.3. Biomaterials: Medical ViewpointL. Sedel, Hôpital Lariboisière, Université Paris, Paris, France2.4. Biomimetic Materials and Transport SystemsR. Lipowsky, Max-Planck-Institut für Kolloid- und Grenzflächenforschung, Golm bei Potsdam, Germany2.5. Materials Science in CatalysisF. Schüth, Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, GermanyR. Schlögl, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany

8892971001042.6. Optical Properties of Materials: “Harnessing” Light through Novel MaterialsP. Chavel, Laboratoire Charles Fabry de l’Institut d’Optique, Université Paris-Sud, Paris, France2.7. Magnetic MaterialsH. Kronmüller, Max-Planck-Institut für Metallforschung, Stuttgart, GermanyJ.M.D. Coey, Department of Physics, Trinity College, Dublin, Ireland2.8. Superconducting MaterialsR. Flükiger, Département Physique de la Matière Condensée, Université Genève, Genève, Switzerland2.9. Materials for FusionH. Bolt, Max-Planck-Institut für Plasmaphysik, Garching bei München, Germany2.10. Materials for TransportationC.R. and W.E. Owens, UniStates Technology Corporation, Medford, Massachusetts, United States1091122.11. Materials Science in SpaceP. R. Sahm, Institut für Giesserei , RWTH Aachen, GermanyG. Zimmermann, ACCESS e.V., Aachen, GermanyConclusionsCONTENTS1151171171181191211221231241241243. MATERIALS – INNOVATION IN MATERIALS SCIENCE BYNEW INTERDISCIPLINARY APPROACHESY. Bréchet, ENSEEG/INP-Grenoble, Saint Martin d’Heres, FranceW. Pompe, Institut für Werkstoffwissenschaften, Technische Universität Dresden, Dresden, GermanyM. Van Rossum, Advanced Semiconductor Processing Division, IMEC, Louvain, BelgiumIntroduction3.1. Present State of Materials Science3.2. Multidisciplinarity in Materials Science3.3. Obvious Needs for New Ideas3.4. Important Topics in Scaling of Materials3.5. Learning from “Mother Nature”3.6. Option for a New Interdisciplinary Approach3.7. Molecular Bioengineering – a New Challenge for Materials Scientists3.8. Expectations for the Near Future3.9. Actions that have to be UndertakenConclusions51271291341381441484. MATERIALS THEORY AND MODELLINGIntroduction4.1. Predictive Modelling of MaterialsA.M. Stoneham, Centre for Materials Research, University College London, London, United Kingdom4.2. From Basic Principles to Computer Aided DesignK. Kremer, Max-Planck-Institut für Polymerforschung, Mainz, Germany4.3. Theory, Simulation and Design of Advanced Ceramics and CompositesC. A. J. Fisher, Japan Fine Ceramics Centre, Nagoya, Japan4.4. Modelling Strategies for Nano- and BiomaterialsH. Gao, Max-Planck-Institut für Metallforschung, Stuttgart, GermanyConclusions1501535. MATERIALS PHENOMENAIntroduction5.1. Thermochemistry of MaterialsF. Aldinger, Max-Planck-Institut für Metallforschung, Stuttgart, GermanyJ. Ågren, Materials Science & Engineering, Royal Institute of Technology, Stockholm, SwedenR. Ferro, Dipartimento di Chimica, Università di Genova, Genova, ItalyG. Effenberg, MSI, Materials Science International Services GmbH, Stuttgart, Germany

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART1581611661761801831875.2. Phase TransformationsE. Mittemeijer, F. Sommer, Max-Planck-Institut für Metallforschung, Stuttgart, Germany5.3. Interface ScienceR. C. Pond, Department of Materials Science & Engineering, University of Liverpool, Liverpool, United Kingdom5.4. NanomaterialsG. J. Davies, Faculty of Engineering, University of Birmingham, Birmingham, United KingdomO. Saxl, The Institute of Nanotechnology, Stirling, Scotland, United Kingdom5.5. Small-Scale Materials and StructuresE. Arzt, P. Gumbsch, Max-Planck-Institut für Metallforschung, Stuttgart, Germany5.6. Colloid Physics and ChemistryM. Antonietti, H. Möhwald, Max-Planck-Institut für Kolloid- u. Grenzflächenforschung, Golm b. Potsdam, Germany5.7. Mechanical Properties of Metals and CompositesP. Van Houtte, Faculty of Applied Sciences, Catholic University of Louvain, Louvain, Belgium5.8. Electronic Structure and CorrelationJ. Kirschner, U. Hillebrecht, Max-Planck-Institut für Mikrostrukturphysik, Halle/Saale, GermanyM. von Löhneysen, Physikalisches Institut, Universität Karlsruhe, Karlsruhe, Germany6192Conclusions1951962012042072102132162192232282326. MATERIALS SYNTHESIS AND PROCESSINGIntroduction6.1. Thin Film ScienceT. Wagner, Max-Planck-Institut für Metallforschung, Stuttgart, Germany6.2. Synthesis and Processing of Inorganic MaterialsJ. Etourneau, I.C.M.C.B., Université de Bordeaux, Pessac, FranceA. Fuertes, Instituto de Ciencia de Materiales, CSIC, Bellaterra-Barcelona, SpainM. Jansen, Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany6.3. Synthesis/Processing of Ceramics and Composite MaterialsT. Chartier, ENSCI, Limoges, France6.4. Synthesis of Polymeric MaterialsP. Lutz, Institut Charles Sadron, Strasbourg, France6.5. Metal-Matrix Composites: Challenges and OpportunitiesA. Mortensen, Swiss Federal Institute of Technology, Lausanne, SwitzerlandT. W. Clyne, Materials Science and Metallurgy Department, University of Cambridge, Cambridge, United Kingdom6.6. Ceramic Matrix CompositesR. Naslain, Laboratoire des Composites Thermo-Structuraux, Université de Bordeaux, Pessac, France6.7. Polymeric Composite MaterialsM. Giordano, S. Iannace, L. Nicolais, Ingegneria die Materialie, Università ”Federico II”, Naples, Italy6.8. Electronic SystemsP. S. Peercy, University of Wisconsin, Madison, Wisconsin, United States6.9. Photonic SystemsP. S. Peercy, University of Wisconsin, Madison, Wisconsin, United States6.10. EcomaterialsK. Yagi, S. Halada, National Institute for Materials Science, Tsukuba, Ibaraki, JapanConclusions

7. ADVANCED ANALYSIS OF MATERIALS235238243Introduction7.1. X-Rays (Synchrotron Radiation)J. Schneider, DESY-HASYLAB, Hamburg, GermanyG. Kaindl, Institut für Experimentalphysik, Freie Universität Berlin, Berlin, GermanyC. Kunz, European Synchrotron Radiation Facility, Grenoble, FranceH. Dosch, Max-Planck-Institut für Metallforschung, Stuttgart, GermanyD. Louër, Laboratoire de Chimie du Solide, Université de Rennes, Rennes, FranceE. Mittemeijer, Max-Planck-Institut für Metallforschung, Stuttgart, Germany7.2. NeutronsD. Richter, Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, Jülich, GermanyK.N. Clausen, Risø National Laboratories, Roskilde, DenmarkH. Dosch, Max-Planck-Institut für Metallforschung, Stuttgart, Germany2472532577.3. High-Resolution MicroscopyM. Rühle, Max-Planck-Institut für Metallforschung, Stuttgart, GermanyK. Urban, Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, Jülich, Germany7.4. Surface Science and Scanning Probe MicroscopyD.A. Bonnell, University of Pennsylvania, Philadelphia, Pennsylvania, United StatesM. Rühle, Max-Planck-Institut für Metallforschung, Stuttgart, Germany7.5. Three-Dimensional Atom ProbeG.D.W. Smith, Department of Materials, Oxford University, United KingdomM. Rühle, Max-Planck-Institut für Metallforschung, Stuttgart, GermanyCONTENTS72592632667.6. Laser SpectroscopyTh. Elsässer, Max-Born-Institut für Nichtlineare Optik und Spektroskopie, Berlin, Germany7.7. NMR SpectroscopyH.W. Spiess, Max-Planck-Institut für Polymerforschung, Mainz, GermanyConclusions2692702722742762782832842842858. MATERIALS SCIENCE IN EUROPEH. Dosch, M.H. Van de Voorde, Max-Planck-Institut für Metallforschung, Stuttgart, Germany8.1. The Importance of Materials8.2. The Role of Basic Materials Science8.3. Social Acceptance of Basic Research8.4. The Interdisciplinarity Challenge8.5. New Schemes for Education, Research Careers and Researcher Mobility8.6. European Centres and Facilities for Materials Science8.7. New Strategies for European Research/Projects and Project Management8.8. Relations between Academia and Industry8.9. International CollaborationAnnex 1 A European Network of Excellence in CatalysisR. Schlögl, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany9. MATERIALS SCIENCE AND BASIC RESEARCH IN EUROPE:CONCLUSIONS AND RECOMMENDATIONS289291296306307309H. Dosch, M.H. Van de Voorde, Max-Planck-Institut für Metallforschung, Stuttgart, GermanyIntroduction9.1. Materials Phenomena and Techniques9.2. Materials Systems9.3. Materials Interdisciplinarity9.4. New Research Strategies and Infrastructures in Europe9.5. Closing Remarks

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGARTP REFACE8Because we live in a knowledge-based andinformation-driven society, Europeans arefaced with the challenge of globalization.This affects European industry, economy,and academia on many levels. However, the productionof new knowledge and know-how is no longer the privilegeof only a few nations. We see a world-wide competitionto establish and promote the very best centres ofexcellence in fields where basic insights and the creationof new knowledge produce emerging technologies. In anattempt to gain global leadership, major companies seekto develop close collaborations with these centres acrosspolitical borders. Unfortunately, in the process they almostcompletely neglect old and established ties to their respectivenational academic research systems.Academic research institutions of the individual Europeanmember states have significantly contributed to thepresent success of advanced technologies and the healthycompetitive atmosphere of European Union (EU) industries.However, these institutions and individual centres,which are traditionally supported by national resources,are too small to maintain leadership in the light of the stiffcompetition from North America, East Asia, and otheremerging parts of the world. In the spirit of Europeancooperation it is therefore absolutely necessary to enhancethe creativity and efficiency of the output of research bycombining the efforts of the very best research centres ofthe EU member states, particularly in fields where basicresearch is expected to create or enhance new opportunitiesfor EU industries. By doing this, we will secure thequality of life in these member states.To promote industrial growth, a vibrant economy, andsocial welfare, Europe must be among the world’s leadersin all fields of materials science and engineering research.That goal is certainly achievable. Innovations in materialsscience abound in nearly all arenas of modern Europeansociety, including environment, energy, agriculture,health, information and communication, infrastructureand construction, and transportation.The future promises equally dramatic advances, makingmaterials science a unique and exciting area of great scientificresearch, with far-reaching industrial, economic, andsocietal impact. We will see “intelligent” materials thatwill enable diverse technologies to respond dynamicallyto changes in the environment. New materials will be synthesizedatom by atom. Indeed, the number of possiblecombinations of atomic assemblies to achieve new structuresand properties is seemingly endless, and thismechanistic understanding will provide powerful toolsfor materials and process development. Quite simply,basic research is the most important research investmenta country can make.The exploitation of these possibilities requires thattalented researchers work in multidisciplinary teams thatbring together scientists in materials science, physics,chemistry, biology, mathematics, informatics, and engineering.Capital-intensive, large-scale research instrumentationwill be required to characterize new materialsfrom their smallest constituents at all scales of assemblyto sophisticated equipment for synthesis, processing, andanalysis. Computational research and engineering will

PREFACE9increasingly make use of supercomputers and computernetworks. Research in materials science and engineeringis capital intensive and its success will depend on internationalcollaboration.In Europe, the knowledge and expertise in basic materialsscience is scattered among various research institutions.Thus, the crucial synergistic effect between universitiesand research institutes of various countries is partlylost and the European materials science potential hasnot been fully realized. A new European policy is neededfor long-term basic materials research. In this respect,the intentions of the European Commission to promotethe basic science research landscape in Europe in thenext 6th Framework Programme (2002 – 2006) are veryrefreshing and beneficial to Europe’s future economy andsocial welfare.The field of materials science has great challenges andis of the utmost importance for Europe; therefore, actionis urgent and necessary. It is within this context that theMax Planck Society, Germany’s primary basic researchorganization, has as many as seven different institutesworking in materials science and appropriates 13 percentof its total budget for materials science, almost as muchas its spends on astronomy and even more than it spendson physics. This demonstrates the importance of materialsscience within the context of the different disciplines.It also reveals the high expectations of the scientificcommunity and of the supporting political forces for aconstant stream of innovation coming from the researchon materials.In this light, the Max Planck Society, together with a largenumber of leading materials scientists in Europe and incollaboration with the European Commission’s ResearchArea, has taken the initiative to prepare the present EuropeanMaterials White Book. It is an assessment of basicresearch in materials science worldwide, highlightingfuture directions and pinpointing research priorities forEurope. Examples of the societal impact of the field aregiven, and topics such as materials education, researchcareers, and the role of the civic scientist are discussed.It is our firm conviction that the European researchcentres, if they join forces, are ready to gain world-wideleadership to the benefit of all of Europe.Gerhard WegnerVice-President of the Max Planck SocietyDirector, Max-Planck-Institut für Polymerforschung MainzProfessor, University of Mainz

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGARTE XECUTIVE SUMMARYManfred Rühle | Helmut Dosch | Eric J. Mittemeijer | Marcel H. Van de VoordeMax-Planck-Institut für Metallforschung, Stuttgart10IIn the year 2000, the Max-Planck-Institut fürMetallforschung in Stuttgart, in conjunction withother materials-related institutes of the MaxPlanck Society, and institutes and universities fromall over Europe, decided to prepare a White Book on thetopic of “Strategies for Future Areas of Materials Scienceand Basic Research in Europe.” The aims of the studieswere:1. To assess the state of the art and pinpoint future challenges,needs, and research priorities,2. To highlight the fundamental scientific opportunitiesin this field,3. To consider the impact of materials science on society,and vice versa,4. To find the best ways of attracting more students tothe field and ensure high-quality education,5. To provide guidelines for science policy makers and tooffer a basis for fundamental materials science programmesin Europe.Preparation of this White Book has involved extensive consultationwith leading materials scientists, primarily withinEurope (most notably from the CNRS in France and theMPG in Germany), but also from the United States andJapan. Discussions were also undertaken with industrialresearch directors and relevant policy makers.Materials science can be defined roughly as “the study ofsubstances from which something else is made or can bemade; the synthesis, properties, and applications of thesesubstances.” This definition covers both natural andsynthetic, traditional and advanced materials. For the purposesof this book, however, the discussion is confined tothose materials that form the basis of modern, futuristichigh technology. These advanced materials include steelsand other metallic alloys; superalloys; polymers; carbonmaterials; optical, electronic, and magnetic materials;superconductors; technical ceramics; composites; andbiomaterials. All of these, and others, are discussed in thisbook in terms of:1. Synthesis and processing to arrange the atoms andlarger-scale components of a system into the desiredconfiguration,2. Composition and microstructure to understand theroles they play in determining the behaviour of materials,3. Phenomena and properties to reveal underlying mechanisms,4. Performance to assess suitability for a given application,5. Materials design and lifetime prediction by theoreticaland computational methods.

The Importance of Materials for Modern TechnologyMaterials science plays a pivotal role in determining andimproving economic performance and the quality of life,particularly in the following areas:Living Environment: Because of pressing environmentalconcerns more efficient use of material and energy resourcesis urgently required. Materials science is helping todevelop new energy generation technologies, more energyefficientdevices, and easily recyclable, less toxic materials.Health: Overcoming disease and providing worldwide medicalcare are high priorities. Materials science, in conjunctionwith biotechnology, can meet this challenge by, e.g.,developing artificial bones and organ implants, safe drugdelivery systems, water filtration systems, etc.Communication: The increasing interconnectedness of ourworld requires faster and more reliable means of communication.The information and associated computerrevolutions closely depend on advances made by scientistsworking on new electronic, optical, and magnetic materials.Consumer Goods: Consumers have come to expect globalproducts/services that are delivered rapidly at reasonableprices. Materials science can improve not only the productsbut also the way they are handled (e.g., packaging),resulting in faster production and delivery times and higherquality goods.Transport: Whether for business, holidays, or space exploration,materials science is needed to provide durable,high-performance materials that make travelling faster,safer, and more comfortable. Examples are the developmentof light-weight aluminium bodies for automobiles,brake systems for high-speed trains, quieter aircrafts, andinsulation tiles for re-entry spacecrafts.EXECUTIVE SUMMARY11Challenges for Basic Research in Materials ScienceSeveral challenges face materials science at the beginningof the 21 st Century. The first is to convince industry,the public, and politicians of the importance of materialsscience in driving modern technological development. Asthere is often a considerable time lag between a scientificdiscovery and its useful application, people can forget thelink that connects fundamental research and future prosperity.Without continued investment in the science base,however, the discoveries of today-and the highly trainedexperts necessary to develop and exploit them-will not beavailable for the innovative products of tomorrow.In the field of materials science, the barriers that divideacademia, government institutions, and industry must bereduced if not completely eliminated. Only in this waywill it be possible to turn fundamental discoveries intopractical applications for the benefit of Europe. Fosteringlinks between researchers, theoreticians, industrial scientists,and managers through collaborative schemes andjoint research institutes is an obvious solution, but manyimportant issues can arise. For example, how can we betterprotect intellectual property rights, and who gets todictate the research agenda? It is also important that professionaladvice on such areas as how to attract investmentfor joint ventures and how to set up spin-off companiesto exploit the results of fundamental research bemade available to public sector scientists.Future Directions and Research PrioritiesGreater emphasis needs to be placed on the fundamentalunderstanding of materials rather than on applied scienceand product development. Naturally, application of materialsis the ultimate goal, but this needs to be built on afirm theoretical basis so that improvements can be mademore efficiently and reliably. Particular attention shouldbe given to understanding a material’s behaviour from theatomic/nano-level via microstructure to macrostructurelevels using advanced analytical techniques and computermodelling. This strategy applies to both the improvementof conventional “bulk” materials, such as steel, andto new functional materials for increasingly smaller,“smarter” devices. As shown in this report, Europe has thecapabilities to provide that fundamental understanding.Materials by DesignIn the past, the search for new and improved materialswas characterized mostly by the use of empirical, trialand-errormethods. This picture of materials science has

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART12been changing as the knowledge and understanding offundamental processes governing a material’s propertiesand performance (namely, composition, structure, history,and environment) have increased. In a number of cases,it is now possible to predict a material’s properties beforeit has even been manufactured thus greatly reducing thetime spent on testing and development.The objective of modern materials science is to tailor amaterial (starting with its chemical composition, constituentphases, and microstructure) in order to obtain adesired set of properties suitable for a given application.In the short term, the traditional “empirical” methods fordeveloping new materials will be complemented to a greaterdegree by theoretical predictions. In some areas, computersimulation is already used by industry to weed outcostly or improbable synthesis routes. Greater Europeancollaboration is required to develop computational tool formaterials and processing development and for propertyevaluation in a “virtual” environment.NanomaterialsThe ability to control, manipulate, and design materialson the nanometre scale (10 -9 m) will be one of the majortechnology drivers of the 21 st Century. Many research programmes,both in academia and industry, have sprung uparound the world over the last few years in an intense effortto harness the potential of these materials for generatingnew functionalities, minimizing waste and pollution,and optimizing properties and performance. Nanomaterialsare being developed from almost every type ofmaterial-including polymers, metals, ceramics, composites,and biomaterials. While not confined to any particularmaterials class or system, nanomaterials, along withthe closely associated fields of smart materials and biomimeticmaterials, are united by the use of a “materials bydesign” philosophy in their creation. Some of the manyassorted applications that are likely to be seen in the futureinclude ultraprecise drug-delivery systems, nanobotsfor micromanufacturing, nanoelectronics, ultraselectivemolecular sieves, and nanocomposites for aircraft andother high-performance vehicles.Smart MaterialsOne area of research that will revolutionize our conceptof synthetic materials, as well as how we interact with oursurroundings, are “smart” (or “intelligent”) materials. Unlikenormal, inert materials, smart materials are designedto respond to external stimuli, adapting to their environmentin order to boost performance, extend their usefullifetimes, save energy, or simply adjust conditions to bemore comfortable for human beings. Materials will alsobe developed that are self-replicating, self-repairing, orself-destroying as required, thus reducing waste and increasingefficiency. Smart materials are being developedby combining regular materials from different classes(metals, ceramics, polymers, biomaterials) in complex architectures(e.g., fracture-sensing composites and artificialmuscles). Combined with technologies for manufacturingand controlling structures on the atomic scale(nanomaterials) and mimicking biological systems (biomimetics),the possibilities for newer and better materialsseem almost endless.Biomimetic MaterialsThe rapidly emerging field of biomimetic materials willform one of the most important technologies of the 21 stCentury. Biomimetic materials seek to replicate or mimicbiological processes and materials, both inorganic and organic(e.g., synthetic spider silk, DNA chips, and nanocrystalgrowth within virus cages). Better understandingof how living organisms produce minerals and compositeswill open up new areas of research and applications. Materialswill be able to be fabricated much more preciselyand efficiently, resulting in new functionalities and increasedperformance (e.g., self-repairing, ultrahard, andultralight composites for aircraft). To develop these materials,we will need new chemical strategies that combineself-assembly with the ability to form hierarchically structuredmaterials.Synthesis and ProcessingThe goal of future synthesis and processing techniques isto allow scientists to construct tailor-made materials fromcomplex arrangements of atoms and molecules with thesame precision and control as currently used for manufacturingsemiconductors. Promising synthesis techniquesdescribed in this report include chemical processingfrom simple precursor units, soft solution processing,rapid prototyping of ceramic and metallic components usingink-jet technology, microwave sintering, gas-phasemethods such as chemical and physical vapour deposition(CVD-PVD) for forming thin films, composite infiltration,and many more.Computational Materials ScienceComputer modelling, using supercomputers, heavy-dutyworkstations, and personal computers, will be an indispensabletool for basic and applied materials science inthe future. It is already an important tool in many areas ofscience and engineering, including drug design, climateprediction, aeronautics, and even personnel training!Considerable progress has been made over the last 20years in the simulation of properties and the processing ofmetals, polymers, and ceramics having increasing complexity.Computational strategies are emerging that pro-

vide physical and chemical descriptions of materials overlarger length and time scales. One of the “hot topics” incomputational materials science today is multiscalemodelling, which aims to cover several length and timescales with one consistent simulation framework.Advanced Analytical TechniquesMaterials scientists will require new and more powerfulanalytical techniques so that they can continue the discoveryof new phenomena and develop improved materialsfor the future. Techniques such as high-resolutiontransmission electron microscopy, scanning probe microscopy,X-ray and neutron diffraction, and various kinds ofspectroscopy allow us to examine materials on the atomiclevel. These techniques need to be developed, improved,and extended further by integrating them with morepowerful computers for rapid visualization of data andcomparison with computer models. These techniqueshave an particular importance in the area of materialssynthesis, where they can also be used for manipulatingand controlling materials on the atomic and nano levels,as in atomic force microscopy.EXECUTIVE SUMMARYMaterials Science, Society, and Research Infrastructure in Europe13The development of new materials and their applicationswill eventually affect everyone, not just those in industry,business, or the academic sphere. At this time, when science,technology and society are all rapidly changing, wemust not only consider how materials science affects societybut also the ways in which society affects the developmentof materials science.Social Acceptance of Materials ScienceThere is a need for an improved public understanding ofall forms of science, particularly of a low-profile disciplinesuch as materials science. The materials science communitymust therefore be more effective in communicatingto the public the manifold benefits it brings. Society investsin research not only for the sake of obtaining newknowledge but also to improve human life. Therefore, thepublic has a right to know what scientists do and howbasic science research and achievements affect society.Basic science is viewed sceptically by an increasing numberof young people, partly because scientists have failedto convey the relevance and motivation of their research tothe nonscientific public.Strategies for increasing the public’s understanding ofscience include events and programmes designed to exposemore high school students to the wonders of science.These can include consultations between materials scientistsand high school teachers and authorities on howto incorporate introductory materials science into schoolcurricula; summer internships in industrial laboratoriesfor high school students; and “sabbaticals” for scienceteachers so that they can take science refresher courses atuniversities. Other venues for improving materialsscience’s public profile can include TV shows on popularscience, research institute/university “open-house” events,and scientific newspaper articles and magazines targetedat the general public that are inspiring and up to date.Political Support of ScienceEuropean governments need to be made aware of theimportance of long-term, sustained support for materialsscience in order to ensure future prosperity and growth fortheir citizens. Although individual scientific ingenuity andcreativity are important, they are no longer sufficient forthe groundbreaking research that leads to new discoveries.Large investments in basic research are needed, whichrequires politicians of vision and leadership.Other ways that European governments can bring aboutchange in the relationship between the overall populationand the scientific community is by (a) creating a favourableclimate for investment in basic research, e.g., throughtax incentives; (b) opening dialogues between scientistsand citizens about scientific issues and the directions Europeantechnology should take; and (c) preparing forwardthinking,long-term science policies that give researchersthe freedom to pursue curiosity-driven research, with supportfor turning new discoveries into practical applications.Finally, to ensure that long-term strategies and researchprograms are founded on sound science, experts in materialsscience should also be included in joint EuropeanResearch Councils and their recommendations disseminatedto industry, academia, and the general public.Basic Research and IndustryBoth industry and academia are under pressure to focustheir efforts on market-related aspects of product/processdevelopment at the expense of an understanding of thefundamental science. Many European companies haveeliminated corporate or central research laboratories to

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART14align their R&D efforts more closely with immediate businessneeds. This is a dangerous policy for the future. Basicresearch is the most important investment that a companycan make, both for its own future and for the future of thesociety in which it operates. Although “blue skies” researchcan be costly in the short term, most breakthroughs, althoughunpredictable, usually result from such research.This report therefore strongly urges all materials-relatedEuropean industries to increase their investment and commitmentto basic research and create flexible researchagendas for making the most of new discoveries andresearch findings.Pursuing a research agenda in isolation, however, can bean expensive and time-consuming process for an individualcompany. Companies and academia alike would benefitfrom improved infrastructure and networks for performingcollaborative basic research. Even large pharmaceutical,chemical, and semiconductor companies that havesubstantial “in-house” research programmes could benefitfrom European-wide networks because of the extra resourcesand manpower at their disposal. Materials-relatedindustries are therefore encouraged to establish and takepart in cooperative research schemes, particularly the newEuropean Materials Centres described below.Materials Science and Education in EuropeEurope needs to do a number of things to ensure that thereare enough highly trained scientists and talented researchersin the field of materials science.• A better public perception of materials science and itsimportance would encourage more young people tochoose a career in this field. The wide range of careeropportunities in materials science needs to be betterpublicized in schools and universities. The top Europeanuniversities should create materials science departmentsthat can attract the brightest students, and thatare competitive with the best departments and institutionsin the world.• Despite the current shortage of students studying materialsscience and choosing careers in this field, the currentstandards of education and training across Europeare generally high. This level must be maintained or,preferably, improved. Students should be exposed to thelatest technological advances and how they are appliedin different fields. At the same time, career educationmust be promoted to inform students about the range ofopportunities and career paths available in this materialsscience.• Highly trained scientists and talented researchers areneeded at all levels of materials research, from industryto academia. Better incentives are needed to ensure thatEuropean researchers continue to work in Europe ratherthan moving abroad, and obstacles to non-Europeanresearchers working in Europe need to be removed. Agrowing number of materials science graduates are turningto careers in other fields. Therefore, steps should betaken to ensure that none leave because of poor careeropportunities or lack of financial rewards. The numberof women studying materials science also needs to beincreased, and greater support provided for career progression.• The ideal balance between basic and applied researchneeds to be found to ensure Europe’s long-term prosperity.The establishment of dedicated European Centresof Competence in Materials Science and Technologythat will undertake fundamental research on behalfof industry, but are also connected to universities, is oneway to make the most of Europe’s scientific potential.– Long-term fundamental research should be pursuedat European Centres for Materials Science, and alsoencouraged at universities, with researchers benefitingin terms of ideas and training from contact withindustry.– Short-term research programs with industrial relevancecan be carried out at the European Centres forMaterials Technology, with input from university andindustrial researchers in a collaborative framework.– Long-term industrial research (to meet particular strategicneeds) should be undertaken within the partnercompany, with the short-term research centre projectsserving as feasibility studies.• Modern materials science is an increasingly interdisciplinaryactivity in which physicists, chemists, biologists,mathematicians, computer scientists, and engineers canall contribute their expertise to a wide range of scientificand technical problems. The growing fields of nanotechnology,biomaterials, biomimetic materials, and smartmaterials will not prosper without intensive crossoverand interaction between disciplines. Fresh ideas, newinsights, and innovations will undoubtedly result fromgreater multidisciplinary interaction. To reap the rewardsof an interdisciplinary approach, universities andresearch institutes need to encourage more flexiblemovement between disciplines by (a) breaking down rigidadministrative structures and (b) setting up multidisciplinarygroups or centres. National governments, fundingagencies, and the EC should also encourage interdisciplinaryactivities by:

– Sponsoring regular workshops, conferences, and summerschools that focus on multidisciplinary areas inmaterials science– Supporting the establishment of cross-disciplinaryresearch programmes– Encouraging agreements between funding agenciesfor the establishment and coordination of multidisciplinarymaterials research, e.g., bio- and medicalmaterials– Granting fellowships and other financial support toscientists moving from one field to anotherMajor Research FacilitiesEquipments – necessary for many important characterizationmethods – are becoming increasingly sophisticatedand are often too expensive for single medium-sizedcompanies or university departments to afford. Therefore,a strong component of the EC’s basic research supportshould be equipping and supporting large multiuserfacilities at specific locations. In the case of materialsscience, these facilities should include the latest highenergyelectron microscopes and synchrotron and neutronradiation sources (e.g., to examine crystal structures andchemical bonding), high-pressure anvils, and supercomputers.They will also serve as a place of contact betweenexperimentalists and theoreticians, and researchers fromdifferent disciplines. In addition, these state-of-theartfacilities will attract the world’s leading scientists,helping Europe to maintain the highest levels of scientificexcellence.European Centres for Materials Science and TechnologyEuropean Centres of Competence in Materials Scienceand Technology need to be established to foster cross-fertilizationof ideas and state-of-the-art science. They shouldinclude a basic research programme that gives graduateand postdoctoral students the opportunity to performworld-class experiments. The centres should also organizeworkshops, short courses, summer schools, industrialvisits, educational programmes, etc., for training scientistsand engineers. These could be newly established “brickand-mortar” centres, “virtual” (i.e., networked) centres, orextensions of current European materials research institutes.The best of them could be designated “MaterialsCentres of Excellence,” with extra funding and higherwages earmarked for these institutes so as to attract thebest and brightest from around the world. This strategywill help motivate European researchers to return toEurope after stints of working abroad.European Research NetworksMaterials science has advanced to the point where it isoften impractical (or indeed impossible!) to assemble inone place all of the intellectual resources and specialityequipment needed for a large-scale project. “Virtual”centres, or networks for materials science will be formedof research laboratories from academia, industry, andmajor facilities. These centres will be linked by highspeedInternet connections and will act as hubs for interdisciplinaryresearch. This will be the most efficient use ofthe research infrastructure and facilities that are spreadthroughout different Member States.EXECUTIVE SUMMARY15General RecommendationsThis study has identified four major themes that can serveas a guideline in discussing the advancement of materialsscience research in Europe:1. The importance of materials science to the prosperityof future Europeans, and indeed, humankind2. The need for better theoretical understanding of materialsand their behaviour, and the fundamental researchneeded to obtain this3. The highly interdisciplinary nature of materials science,and the excitement and personal rewards that a careerin this field can bring4. The need for continued, long-term investment, particularlybasic research, by national governments, industry,and the European CommissionThe relevance of materials science to modern society needsto be emphasized and promoted beyond the researchcommunity and industry to governments and the generalpublic. Forward-thinking and sustainable initiatives formaterials science research need to be launched that willattract the world’s best scientists and ensure that morefundamental discoveries come our way during the nextcentury. With the cooperation of government, industry,academia, and the general public, European materialsscience research can remain at the forefront of developments.We hope that this report will aid the discussionof how this can best be achieved.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGARTI NTRODUCTIONM. Rühle | Max-Planck-Institut für Metallforschung, Stuttgart16Humankind’s existence has always depended on theavailability of materials. Indeed, historians use thedominant materials of an ancient era to classify it:they speak of the Stone Age, the Bronze Age, the IronAge. This reliance on materials has continued to the presentday, not only for our physical existence – clothing, buildings,transport, and the innumerable other inventions that havemarked human progress – but also for our cultural and intellectuallives as well-literature, art, music. In fact, withoutmaterials the human endeavour would hardly be conceivable.The latter half of the 20 st Century was characterized by profoundimprovements in our knowledge and ability to createnew materials to a degree that could only be dreamed of ahundred years ago. These advanced materials underpin allmodern technologies, from silicon chips to jet engines to medicalimaging. Because of this increased use of and reliance onnew materials, society needs to refocus its emphasis on materialsdevelopment, something that it has often neglected inthe past. This requires a re-evaluation of the role of materialsscience in society in order to guarantee the availability of newtools with which to solve some of the most pressing problemsthe world faces today, such as environmental pollution, adwindling supply of resources, overpopulation, and diseaseepidemics.The growing public awareness of these issues coincides withthe intention of the European Commission (EC) to reshapethe fundamental research landscape in Europe. This hasresulted in closer links between the EC and the Max-Planck-Institutes involved in materials science and inspired theidea of compiling this White Book on “Fundamental Researchin Materials Science.”Work on the project began with a discussion meeting betweenJune 13 and 15, 2000 at Ludwigsburg, near Stuttgart, Germany,in line with the preparation of the new EC 6 th FrameworkProgramme (2002 – 2006). About 75 leading scientists fromEurope and the U.S., including experts in the disciplines ofmaterials, mathematics, physics, chemistry, biology, informationtechnology, and engineering, met for two days of brainstormingabout the many different aspects of materialsscience. (The programme is provided in Appendix I and thelist of participants in Appendix II).Topics were selected and reviewed. For each topic, acknowledgedexperts introduced the state of the art and presentedtheir visions for future evolutionary developments andrevolutionary breakthroughs. This was followed by opendiscussions with scientists in the audience.After the workshop, teams were formed and team coordinatorsappointed. Each coordinator and team provided awritten summary of their discussions and ideas. Emphasiswas placed on the directions and opportunities for futurematerials research, with reference to the social and economicimplications where relevant. This input formed the basisof this White Book.The initial conclusions, recommendations, and futureresearch opportunities resulting from this exercise werediscussed further at a second workshop on March 15/16, 2001in Degerloch, again near Stuttgart. (The programme is providedin Appendix III and the list of participants in AppendixIV). Attendance at this meeting was limited to the coordinators,policy makers, representatives of the EC Director-General for Research, heads of national laboratories, andindustrialists.Throughout this period, close contact was maintained withthe EC Research Directorate for Materials to coordinate ourefforts to resulting in new research initiatives.

The format of the White Book follows the format of thissecond meeting. That is, a wide variety of different classes ofmaterials and techniques are examined from as many viewpointsas possible. Contributions from many differentauthors, all respected and acknowledged experts in theirfields, are grouped under the following chapter titles: (1) Materials:Science and Engineering; (2) Materials: Science andApplications; (3) Interdiscipinarity in Materials Science; (4)Materials Modelling and Materials Theory; (5) MaterialsPhenomena; (6) Materials Synthesis and Processing; and (7)Advanced Analytical Techniques. Individual scientists orteams of scientists wrote the individual chapters of each section.The author(s) bear(s) full responsibility for the contentof their chapter. (A list of authors is provided in Appendix V).A few topics were discussed and analyzed by differentscientists from different points of view. This has led to a slightoverlap of a few topics.It should be emphasized that the White Book does not claimto cover all areas of materials science in detail. The chosensubjects reflect the view of the individual scientists present.Nevertheless, we believe that we have covered the main topicsrelevant for the broader development of materials science.The White Book sheds light on recent advances in fundamentalresearch in each of these materials-related fields. It highlightsthe great importance for new synthesis and characterizationmethods, the search for new phenomena and materials,and the growing use of computer models and theoreticalunderstanding in all areas of materials science. One of themajor theme, which came through clearly and consistentlyfrom both, the meetings and the articles contained in thisbook, is that the future of materials science lies in the crossoverand exchange of ideas between disciplines. Consequently,a special chapter (Chapter 3) has been devoted to the interdisciplinarynature of materials science and how best tofoster it. This interdisciplinary aspect must also includeengineering. Because fundamental research in materialsscience eventually results in a product that serves society,materials – both traditional and advanced – must be “engineered”at all length scales. Engineering at the smallest lengthscale results in “nanomaterials” which open up new researchhorizons; not only for tailoring complex materials withspecific and superior properties, but also for exploring newphenomena that arise when matter is confined to withinmolecular-sized structures.An expansion of interdisciplinary research would be to considermaterials science, including fundamental research, as aholistic concept ranging from processing to recycling ofmaterials – each step emphasizing also ecological aspects.The holistic approach of materials science is essential for thefuture welfare of society.Chapter 8 examines the social aspects of science, includingnew schemes for materials education, careers for researchscientists, and inter-European and international mobility ofresearchers. In addition, a new strategy for basic materialsscience research in Europe is presented, with suggestions onhow to organize European research efforts to the best effect.The overall conclusions, recommendations, and directionsfor future research are summarized in the final chapter (Chapter9), which highlights the importance of basic materialsresearch to economic growth and prosperity. This chapter alsoprovides insights into the research needs of various materialsclasses and gives directions for future research opportunitiesand activities in the materials science area.The book as a whole is oriented towards fundamental aspectsof materials research, but visions of the future and otheropinions from industrial research authorities were also takeninto consideration. An important example of this is the rolethat basic materials research will play in future Europeantransportation systems. Materials science also has an importantpart to play in alleviating many of the environmentalproblems that we now face, not least of all by developing newenergy-efficient devices using fast ionic conductors andimproved catalysts.The audience for this book, therefore, is large. It is addressedto all materials scientists and scientists from materials-relateddisciplines in Europe, as well as national and European policymakers. Because of the necessity to focus on materials development,this book is also of important to industry, especiallysmall and medium-sized enterprises. As well as providing anup-to-date account of the latest technology and research topics,it also provides ideas for future innovations, devices, andapplications of materials. If these can be developed by Europeanindustries, then Europe’s economic prospects, and consequentlyits citizens’ welfare, will be much the better for it.This book serves as a call to European politicians to upgradetheir investment in basic materials science at least to a levelcomparable with that in other industrialized countries,notably the U.S. and Japan, so that European industry canremain competitive well into the future, and we can pass on aculturally, scientifically, and economically flourishing Europeto future generations.The editors of the White Book thank all the authors, helpers,workshop participants, and colleagues from all participatingMax-Planck-Institutes, and The Max Planck Society, for theenormous effort they have put in to making the publication ofthis book possible. The support by Dr. Stephan Krämer, MPIfür Metallforschung Stuttgart, during the editing and printingof the White Book is greatly acknowledged.We trust that this White Book will result in the reinvigorationof materials science in Europe. We especially hope it will openthe eyes of the public, opinion makers, and politicians to thewonders of materials science, the benefits it brings, and itsrole as one of the main pillars of economic progress and socialwell-being in Europe and, indeed, the world as a whole.INTRODUCTION17

CHAPTER 11. MATERIALS: SCIENCEAND ENGINEERING1819Materials science is an interdisciplinary researcharea which covers the physics, chemistry and engineeringof all classes of materials. Traditionally, thesematerials are divided into metals and metallic alloys,ceramics, semiconductors and other inorganic materials,and polymers and organic materials. Recently, the scienceof materials has received increased attention because ofthe discovery of new classes of materials and their applicationin new technologies.▲The traditional classification of materials into differentclasses or types is still helpful since specific engineeringapplications still rely on components made from materialsfrom one or other of these groups. In this chapter it will beshown that metals and metallic alloys (including composites)still constitute the majority of structural and functionalmaterials used within the EU, as well as worldwide.Use of this group of materials has an enormous technologicaland ecological impact on society, and one of the challengesof materials science is to come up with metals withimproved properties via cheaper processing routes. This isespecially true for the automotive industry where synthesisand processing controls the microstructure, properties,and performance of metallic materials. It is now well appreciatedthat for this industry-which consumes enormousamounts of metals-to be sustainable, automobile designmust encompass the complete lifecycle of the materialsused, from processing to recycling.Microstructure of polytype SiAlON (transmission optical micrographobtained with polarized illumination, U. Täffner, MPI für MetallforschungStuttgart).IntroductionThe distinction between ceramics and other non-metallicinorganic materials is often difficult to define. In this chaptertwo aspects of these materials are described, namelyfundamental research and real-world applications. The futureof non-metallic materials appears to lie in developmentand exploitation of specific functional properties. Asa group, ceramic materials have perhaps the largest rangeof functions of all known materials, and can be used for adiversity of applications. It is very important to understandthe fundamental processes which lead to specific properties.In simple terms, ceramics are compounds or mixturesof compounds of metallic or metalloid elements with nonmetalelements.The properties of a particular material depend not only onthe chemical nature of its atoms, but also on their arrangementand distribution in its microstructure (grains, pores,etc). Materials with specific thermal, mechanical, nuclear,electrical, magnetic and optical properties can be fabricated.Due to the staggering variety of these materials andtheir possible combinations, there is still a huge amount ofresearch that needs to be done. So far only a fraction of theinorganic materials that could possibly be put to use havebeen studied, and there is little doubt that many new compoundswith unusual or superior properties are still to befound.Inorganic solid state chemistry and physics investigate thebasic principles and provide the necessary background forresearch into the correlation between microstructure andproperties of inorganic compounds. Insights can beengained simply by comparing phenomena of different ma-

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART20terials with each other, but more rigorous understandingbased on quantum theory is also necessary for today’sadvanced materials.Polymers find increasing number of applications everyyear. Recently, however, research into “traditional” polymershas declined. At present the polymer manufacturingindustry in Europe is undergoing major restructuring,which has led to severe cutbacks in companies’ Research& Development (R&D). To fill this gap, universities shouldincrease the amount of fundamental research they do intopolymeric materials.All life-forms are based on soft organic materials; polymerscience can therefore also be related to our understandingof biological materials, particularly carbon-based materials.Ceramics, on the other hand, are similar to hard biologicalmaterials such as teeth and bone, so that connectionsbetween these two fields will continue to grow aswell. We can expect many more functionally useful materialsto become available in the future by manipulating thechemistry and processing techniques of all these materials,and combining them in new ways.It is difficult to imagine modern society functioning todaywithout electronics. Electronic, optical, and photonic materialsplay essential roles in information technology, computing,and systems control, as well as electronic consumergoods. There is a great deal of commercial pressure todevelop new materials for use in these areas. Fundamentalresearch into electronic, photonic and optical materialsis therefore essential for the continued improvement andminiaturization of electronic and photonic devices.The following eleven sections summarise the state of theart for the different classes of materials. Expected evolutionaryand revolutionary developments are sketched ineach section.Carbon materials have received a lot of attention recentlythrough specific modifications such as graphite sheets(rolled up to form nanotubes or buckyballs) and syntheticdiamond. The basic principles of inorganic carbon chemistryare understood. These specific forms of carbon areexpected to be useful for a variety of applications in differentbranches of engineering. Hence it is very importantthat links between the science of carbon and itsapplications be strengthened.

1.1. Metals and Composites: Basis for Growth, Safety, and EcologyD. Raabe | Max-Planck-Institut für Eisenforschung GmbH, 40074 Düsseldorf, GermanyContributors:Y. Bréchet (LTPCM, BP75, Domaine Universitaire deGrenoble, Saint Martin d’Heres, France), G. Gottstein (Institutfür Metallkunde und Metallphysik, RWTH Aachen,Aachen, Germany), J. De Hosson (Department AppliedPhysics, University of Groningen, Groningen, The Netherlands),P. Van Houtte (Department MTM, CatholicUniversity Louvain, Louvain, Belgium), V. Vitek (Departmentof Materials Science and Engineering, University ofPennsylvania, Philadelphia, U.S.).1.1.2. State of the Art and Expected TrendsThe state of the art in the field of metals and compositesresearch is characterized by a mature level of property optimizationand characterization particularly as far as bulkmechanical aspects of conventional structural metallic materialsare concerned. Basic principles behind bulk materialskinetics and thermodynamics in such alloys are understoodto an extent that they can be used for the further gradualoptimization of existing alloy concepts with respect tostructural and/or functional properties. Recent Europeanprogrammes have focussed on improving and tailoring existingmaterial concepts for matching technological andcommercial boundary conditions and on designing newmaterials concepts beyond conventional R&D lines.This research concept of the past decade has for manyaspects matured to a level where future activities, whenMATERIALS: SCIENCE AND ENGINEERING211.1.1. The Place of Metals in the World of MaterialsMetallic alloys and composites represent the dominantgroup of structural and functional materials world wideand within the EU. This applies for their technological impacton society as well as for the scientific challenges associatedwith further discoveries and developments in thisfield. Fundamental and long-term oriented research onmetals and composites leads to the development of welltailoredtechnological solutions which serve society withrespect to sustainable progress, ecological benefits, advancedsafety demands, and economic success. Prominentchallenges along these lines lie in understanding anddeveloping the fundamentals of lightweight structural materialsand design solutions, self-organising microstructures,failure-tolerant materials systems, smart materials,and materials for ground and aerospace transportation(Fig. 1.1 and 1.2).Fig. 1.1. Space vehicles which are at the cutting edge of high technologyare built of structural elements of steels, aluminium, magnesiumand beryllium alloys and metal-matrix composites.This report gives an overview of the most important futureresearch topics in the field of metals and composites researchas collected and discussed within a group of about100 leading experts from the EU, Asia, and the U.S. Itgives corresponding recommendations for future basicresearch initiatives on metallic alloys and composites inthe 6 th EC Framework Programme.Fig. 1.2. Modern automotive technology relies on safety equipmentmade of advanced steels, aluminium, and magnesium alloys.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART22designed and pursued along the same lines as before, willlead to a more and more asymptotic research progress. Futurelong term research programmes must, therefore, formulateconcepts to achieve distinct progress steps leadingEC projects beyond existing research plateaus. This approachwould maintain and strengthen the position of metalsand composite research as a key science and technologyproviding progress-critical input to other key areas ofscience and high technology. It should thus be the aim offuture research in this field that coming technology applicationsare being pushed forward by materials rather thenvice versa.Some key rules can be formulated to unleash unused potentialof metallic and composite materials through a newEuropean framework research initiative with the aim ofentailing fundamental progress steps pushing this disciplinebeyond existing R&D asymptotes.• First, EC projects should make extensive use of novel experimentaland theoretical tools as well as advanced combinationsof them. Although further improvements and applicationsof well developed “workhorse” methods are essentialto provide serious and systematic data for novelmaterials concepts, it is less likely that they play a bottleneckrole in future metals research such as the use of novelmethods which will allow new observations, which havenot been made so far (some of the new research tools willbe specified below).processingmicrostructuredesign• Second, EC projects should address fundamental longtermproblems of existing and cutting-edge structural andfunctional metallic materials concepts which are the basisof our economy but are not covered by applied or industryresearch. In this context it is important to note that industrypushes materials developments only to a level of immediatecommercial output and leaves behind numerous unansweredquestions which often affect ecological, economic,performance, and safety aspects. Such conceptsdeserve in part more attention from the fundamental sidein order to avoid long-term misconceptions and exploit anddevelopment better the potential of existing materials.• Third, EC projects should create materials concepts farbeyond conventional approaches, focussing particularly onso far less exploited combinations of different materialclasses, property-structure integrations, and property profiles.In this context it is important that new materials developmentshould be accompanied from the beginning byfundamental research since material development is nowadaysan integrated and interdisciplinary task.• Fourth, future research initiatives should give very highpriority to projects with highly interdisciplinary characterclosely integrating concepts and approaches from areassuch as materials physics, materials engineering, informationtechnology, materials chemistry, mathematics, and/orbiology.1.1.3. Outline and Principles of Future Research StrategyThe basic research strategy required in this field can beclassified into two major disciplines. The first one comprisesexperiments on model systems. The second one comprisesmodelling and computer simulation. As far as metalsand composites are concerned the latter branch particularlyconcentrates on macro- and mesoscale simulationissues.synthesismetals for growth,ecology, and safetypropertiesExperiments on model systems should map essential ingredientsof composition, synthesis, processing, and microstructuredesign which are not well understood but havekey functions in novel material design as well as advancedconventional materials concepts (Fig. 1.3). The followingkey points might characterize projects in this field:performanceFig. 1.3. Essential elements of advanced metals and composites research.• First, projects should make use of novel experimentaltools and/or advanced combinations of experimental toolsexploiting observation methods that have not yet maturedto their full potential. Examples (see section 1.1.4) arenano-mechanical property characterization in conjunctionwith nanoscopic analytical and orientation characterization;3D atom probe methods; high-resolution analyticalmicroscopy in conjunction with automated high-resolutionorientation imaging microscopy; 3D synchrotron X-ray microscopy; field ion beam microscopy in conjunctionwith high-resolution orientation imaging microscopy in

FEG (FEG = field emission gun) scanning electronmicroscopy; advanced neutron scattering methods; in situexperimentation combining sample observation with heatingor mechanical loading. Consideration must also beplaced on fast and appropriate analysis tools which arecapable of extracting and visualizing relevant informationfrom the ever increasing experimental data sets.• Second, projects should address fundamental long-termproblems of existing structural and functional metallic materialsconcepts by use of model experiments which are thebasis of our economy but are not covered by applied or industryresearch. Examples are integrated model design solutionsexploiting materials as well as constructional aspects;metal-metal interfaces and grain boundary triplepointsin the form of well-defined model bi- and tricrystals;metal-metal joints; advanced structural-functional as wellas smart compounds.• Third, projects should create experimental model systemsheading beyond conventional approaches, focussing particularlyon so far less investigated combinations of differentmaterial classes, microstructures, and property profiles.Examples are entangled, cellular and porous metallic microstructures;nanoscale metal-polymer compounds; ultrathin layered metal-ceramic-polymer structures; nanostructuredfunctional-structural composites; woven metallicsystems; nanoscale integration of metals, polymers, andceramics; self organising metal-polymer interfaces; compositefoams; and metal-semiconductor-polymer sheetcompounds.Modelling and computer simulation projects should aimat a fundamental understanding and a prediction of theperformance of novel and advanced conventional structuraland functional materials. The recognition of these basicneeds from the theoretical side, along with the ever increasingcomputing power, has established computer modellingapproaches as one of the major areas in materialsresearch. In this approach one formulates model descriptionsbased on fundamental principles and investigatestheir properties and behaviour by numerical simulations.Modelling and computer simulation will play a key role inunderstanding, tailoring, and predicting materials synthesis,processing, microstructures, and properties. Whilemodelling can produce realistic results for very complexsituations, underlying theories, based on results of modelling,must be built as history-dependent and multi-scaleconcepts, integrating electronic and atomic level as wellas continuum scale information whenever relevant(Fig. 1.4). These allow generalization and deep physicalunderstanding of phenomena studied. Modelling and simulationtools have in recent years matured to a state whereavailable software is increasingly well designed and maintainedand built on robust theoretical and mathematicalgrounds.MATERIALS: SCIENCE AND ENGINEERING23• Fourth, design of model systems should be particularlypursued in projects with highly interdisciplinary characterclosely integrating concepts and approaches from materialsphysics, materials engineering, materials chemistry,mathematics, information technology, and/or biology. Examplesare the application of nanoscale materials mechanicstests to large sets of material samples or graded samplesusing variational alloy chemistry methods in conjunctionwith nano-indentation; the design and investigationof metal-polymer interfaces with high-resolution analyticalexperimental tools as projects between metal physics,physical chemistry, and process engineering; determinationof elastic and plastic response of ultra thin layeredstructures under thermal, electromagnetic, mechanicalloadings, or environmental loadings as projects betweenmetal physics, physical chemistry; process engineering;design and investigation of self organization effects in metal-polymerand metal-ceramic interfaces as projectsbetween ceramics, metal physics, physical chemistry, andbiology; and closer cooperation between experts from theoryand experimentation.Fig. 1.4. Important hierarchical scales of computer simulation methodsin the field of metals and composites research. Future developmentsmust integrate macroscopic finite element predictions, mesoscalemethods, and atomic scale simulations for the design and optimizationof new advanced products.Distinct progress steps pushing this field of computersimulation forward can only be expected when the abovementioned key points are considered. This means that

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART24• First, projects should make use of and better integratenovel tools from theory, mathematics, and information technology.Examples are better exploitation of parallel algorithmsand parallel computing power; application of distributedcomputing based on high speed network connections;development of robust and fast parallel non-linearvariational methods for tackling large quantities of coupleddifferential equations; critical reliability investigationsof numerical methods and existing codes; standardizationand sharing of computer codes and resources; closerintegration of electronic ground state and atomic scalecalculations into continuum concepts; improvement ofphysically motivated strain gradient and crystal plasticitycontinuum theory; better integration of and comparisonwith experimental data in case of non ab initio methods;development of fast though robust simulation algorithmsfor the electronic, atomic, and continuum scale; and directcoupling of electronic and atomic dynamics simulationsbeyond the Born-Oppenheimer approximation. Furthermore,particularly large scale simulation efforts requirecloser integration of materials and constructional/design issues. For instance, aspects such as the overall partstiffness results from ingredients of both areas. Such projectsshould introduce design-oriented database-relatedapproaches exploiting artificial intelligence methods. Anotherimportant point of integration are joint simulationsof functional – constructional devices. Also, one shoulddraw more attention to novel information treatment methodssuch as the neural net and fuzzy logic approaches.• Second, simulations should aim at structure- and propertypredictions of model systems pertaining to existingstructural and functional metallic materials. Focus shouldbe placed on the mesoscopic and macroscopic scale.Examples are anisotropic continuum scale CPFE-basedsimulations (CPFE = crystal plasticity finite element methods)of elastic-plastic co-deformation of metallic systemsas well as corresponding simulations considering metalpolymerand metal-ceramic compounds; micromechanicspredictions of polycrystalline matter under mechanicalloads; micromechanics predictions of woven and foamcomposites; joint microstructure simulations integratingcasting, thermomechanical and cold forming issues; andGL-based simulations (GL = Ginzburg – Landau – typephase field methods) of structure- and concentration-dependenttopological mesoscale aspects.• Third, simulations should aim at designing and predictingstructure- and properties of novel material concepts atthe electronic-, atomic-, meso-, and macroscale. Examplesare LDF-type electronic scale predictions (LDF = localdensity functional theory) of the influence of foreignatoms on metal-metal interfaces; MD-based simulation(MD = molecular dynamics) of interfaces and crack tipsunder loads; CPFE-based continuum scale simulations ofbehaviour under elastic-plastic loads; GL-based simulationsof metal-polymer, metal-semiconductor, and metalceramiccompounds; mesoscale joint GL- and CPFEbasedpredictions of self organization kinetics at metalpolymerinterfaces; micromechanics predictions for wovenand foam composites; atomic scale process design simulationsfor micro- and nanoscale compound tailoring usinghyperdynamics concepts.• Fourth, simulation projects should be particularly pursuedin projects with highly interdisciplinary characterclosely integrating concepts and approaches from materialsphysics, materials engineering, materials chemistry,mathematics, information technology, and/or biology. Examplesare the integration of electronic ground state simulationinto continuum models as projects between physicsand materials science; integration of polymer mechanicsand metal mechanics into predictions of layered structuresas projects between materials mechanics and physicalchemistry; development of faster simulation methods andalgorithms as projects between mathematics, informationtechnology, metal physics, and chemistry; the developmentof parallel and distributed methods as projectsbetween mathematics, information technology, metalphysics, and chemistry; and closer cooperation betweenexperts from theory and experimentation.1.1.4. Details of Future Research Programme(a) IntroductionBased on the concept explained in Sect. 1.1.2 this partgives a more detailed outline of recommendations forfuture research topics in the fields of metallic alloys andcomposites. The organization of topics in this chapterfollows in the first place the key subjects as agreed at theLudwigsburg symposium but gives suggestions with relationto the above introduced organization of projects intomodel system experimentation and computer simulation.The key areas of future fundamental research in the fieldof metallic alloys and composites as agreed at the Ludwigsburgsymposium are:• Interface science and microstructure design• Thermodynamics and kinetics• Synthesis and processing• Mechanical and functional properties(b) Interface science and microstructure designLaws of interface motion and energy often follow strongdependencies on state variables. Metal and composite

interfaces typically have bottleneck function in materialsproperties and design. It is likely that substantial new fundamentalinsights and outstanding progress in performancecan be expected particularly from metallic alloysand composites with a high density of homophase and heterophaseinterfaces. Such concepts can be realized in theform of bulk systems with intricate 3D interface percolation,layered systems, and bamboo-type structures.The key focus in this area is a better understanding of nucleationevents and the role of the mechanisms of interfaceformation as well as interface motion. Materials aregetting increasingly dominated by interfaces. This includesmetal / ceramic, metal / metal, metal / polymer etc.interfaces. Investigating such phenomena requires to focuson the electronic and atomic aspects as well as onmacroscopic aspects.Topics in this context with fundamental importance include:(c) Thermodynamics and kineticsThermodynamics and kinetics data are essential for tailoringand predicting novel materials. Particularly in interfacedominated systems thermodynamics and kinetics arenot well understood though they have key function in novelmaterials design. Topics in this context with fundamentalimportance include:1. thermodynamic and kinetic data of multi-componentsystems and interface-intensive systems2. transformations under elasto-plastic and electromagneticloads, effects of point and line defects oninterface transformations3. transformation in confined, low-dimensional, layered,and small scale structures4. development, standardization, and intercalibration inthe field of experimental materials thermodynamics5. Non isothermal and reversal problems in heat treatment6. microstructures arising from competing kineticsMATERIALS: SCIENCE AND ENGINEERING251. self-organising and self-repairing surfaces andinterfaces2. generation, structure, and properties of interfaces withfractal dimension3. nano- and microtribology4. interface and surface systems under thermal, elastoplastic,electromagnetic, environmental and coupledloadings5. surface- and strain-driven continuous anddiscontinuous subgrain coarsening6. elastic-plastic and functional interaction acrossheterophase and homophase interfaces7. nucleation phenomena8. mechanics at interfaces9. interfaces and surfaces turbine blade alloys undercomplex loadings10. functional/structural optimization of interfaces11. interface phenomena in woven and foamed metals andcomposites including corrosion12. role of interfaces in smart materials, particularly innanoscale filter, electronic, and catalytic matter13. interface mobility and effects of other lattice defects,triple junction effects14. recrystallization and grain growth phenomena15. orientation and misorientation evolution at thenano- and microscale16. grain cluster-mechanics17. micromechanics of interfaces and surfaces18. precipitation phenomena under complex loadings,in constrained and layered systems, and in multicomponentsystems19. interface design and manipulation(d) Synthesis and processingMicrostructure design will play a critical role in the synthesisof novel multi-layered and small scale structured materials.Key points to be addressed are the fundamentals of:1. self-organization and self-assembly of microstructureswith desired properties2. in situ processing of functional-structural materials3. layered and graded structures4. super strong metals composites, matter close to thelimits of theoretical strength5. ordering effects of magnetic particles and domains6. metallic foams7. casting defects8. microstructures inheritance in materials processing9. nanoscale particles: processing, self organization,quantum dots10. fabrication of bulk and thin film nanostructuredmetals11. microstructure percolation effects12. intermetallics and oxides: combination of highstrength, ductility, and creep/fatigue resistance,internal oxidation13. in situ nanostructuring through deformation,metallurgical methods, deposition, and diffusion14. in situ decomposition15. field assisted annealing16. high temperature alloys and compounds: turbinematerials, aerospace composites, alloys for hot andaggressive environment17. joining processes

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART26(e) Mechanical and functional propertiesA strong overlap should be created between interface andplasticity projects. In the field of plasticity the followingareas of fundamental interest were identified:1. collective behaviour of structural defects2. scale-bridging plasticity and failure concepts inmaterials simulation and experiment3. elasticity and plasticity in confined, layered, graded,and nanoscaled materials4. effects of solute elements on work hardening5. anisotropic elasto-plasticity of polycrystalline matter6. internal stresses in conjunction with plasticity andtransformation7. void nucleation and coalescence8. mechanics of entangled and percolated systems:metal wool, cellular solids, dendritic structures, scaleand gradient effects in plasticity9. textures at the micro- and nanoscale: coupled stressand texture determination10. interaction between environment and plasticity11. high strength - high conducting composites12. grain cluster mechanics13. mechanical, transformation, and precipitation fundamentalsof novel lightweight Mg, Be, Al, Fe alloys andintermetallic-based lightweight alloys under complexloadings14. mechanical properties of alloys and intermetallicsdoped with rare earth elements15. integrated structure and materials optimization:integrating design and materials properties16. mechanical-functional materials properties as inverseproblems, i.e. back-extrapolation of optimum thermodynamicsand microstructures from desired finalproperties.1.2. Advanced Ceramic Materials: Basic Research ViewpointF. Aldinger | Max-Planck-Institut für Metallforschung, 70569 Stuttgart, GermanyJ.F. Baumard | ENSCI, 87065 Limoges, FranceContributor:R. Waser (Institut für Festkörperforschung, ForschungszentrumJülich GmbH, Jülich, Germany).1.2.1. IntroductionCeramics are a class of materials broadly defined as “inorganic,nonmetallic solids”. They have the largest range offunctions of all known materials. Despite the already existingvariety of compounds, the number of processingtechniques, and the known diversity of properties and applicationsof the materials, all advanced countries sharethe need for basic research in several areas: finding newcompounds with improved specific properties, increasingknowledge of fabrication processes for economical and ecologicalceramic parts production, miniaturization and integrationof ceramics with similar or dissimilar materials, andbuilding a better understanding of materials behaviourthrough computational modelling.1.2.2. State of the ArtThe last decades have seen the development of the enormouspotential of functional ceramics based on uniquedielectric, ferroelectric, piezoelectric, pyroelectric, ferromagnetic,magnetoresistive, ionical, electronical, superconducting,electrooptical, and gas-sensing properties.Such properties now constitute the basis of a broad fieldof applications (Fig. 1.5). Scientific advances concerningmany ceramic materials have enabled technological breakthroughsof truly global proportions.Similar scientific developments also have taken place instructural ceramics. Thermal, chemical, and mechanicalstability of many oxide and nonoxide compounds laid thefoundation for improved processing, which led to an improvedlevel of microstructure design and defect control.This in turn resulted in never-before-seen improvementsin mechanical performance and in the reliability of theproperties of components and devices.In addition, superior combinations of thermal, insulating,and mechanical properties have become the basis of hugeapplications in the packaging of microelectronics and

IC-PackagesSubstratesDielectricsIR OpticsRadomesopticalMgOLampsZrO 2B 4 CSiCAl 2 O 3 Si 3 N 4HealerIsolation PartsHeat ExchangerBurner NozzlesthermalCruciblesEngine PartsDies andMoldsPbZrTiO 5ResistorsBearingsMagnets electricalAdvanced CeramicsmechanicalmagneticalElectrolytesAINBNSealingsPiezoelectricsWear PartsSensorsBaTiO 3 Al 2 TiO 5Cutting Tools 27MATERIALS: SCIENCE AND ENGINEERINGNuclear FuelsnuclearchemicalPumpsFiltersShieldsAbsorbersCatalystsCorrosion andWear PartsFig. 1.5. Functional and structural applications of advanced ceramics.power semiconductors. Therefore, ceramic materials havenow become the cornerstone of such advanced technologiesas energy transformation, storage and supply, informationtechnology, transportation systems, medical technology,and manufacturing technology (Fig. 1.6).Since technical and economical progress in such areas isin line with the mastering of materials, empirical fabricationprocedures are progressively being replaced by knowledge-basedproduction and engineering. Therefore, today’sEnergyTechnologyTransportationTechnologyCERAMICSManufactureTechnologyInformationTechnologyMedicalTechnologyFig. 1.6. Technology areas which benefit from advanced ceramics.advanced materials synthesis and processing, and the economicalmanufacturing of components and devices are beingdriven more and more by an increased understandingof the underlying fundamental scientific phenomena.1.2.3. Trends in TechnologySince production and engineering of materials and componentsare increasingly knowledge-based, the technologyitself reveals gaps in the basic understanding of materials.Such gaps limit the degree to which materials technologycan be competitive with other technologies. Therefore,the continued pursuit of additional knowledge will alwaysbe necessary. Some technological trends are important tofollow as present and future directions of basic and appliedresearch. The most significant of these are:• Increasing materials complexity because of increasedfunctionality• Integration of different materials into multifunctionalcomponents• Miniaturization of devices• Exploitation of nanosized effects

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART28• Theoretical treatment and modelling of materials andcomponents developmentIn addition to these trends, present-day environmental regulationsand awareness and the recycling of materials willaffect the use of materials and require less expensive productionprocesses.According to these trends in materials research, a changein paradigm can be observed. Traditional materials-orientedresearch is now complemented by more interdisciplinaryand method-linking work, while at the same time thedifferent hierarchies of length scales are also considered(Fig. 1.7). Size hierarchies extend from the architecture ofstructures at the atomic and molecular scale (via microstructurecharacteristics in nano- and microsized dimensions),up to macroscopic features of components and devices.One fundamental area of research to pursue is thedevelopment of a unified description of deformation andfracture in order to design microstructures for improved1.2.4. Needs for Future Basic ResearchFollowing technological trends, the needs for future basicresearch in the field of ceramics can be divided into fourmajor areas: (a) materials and materials properties researchin order to widen the area’s scope and match its needs forfuture applications, (b) research to increase the knowledgeof economical and ecological production processes formaterials, components, and devices, (c) miniaturization andintegration, and (d) modelling and numerical simulation,which would complement or even act as a substitute forpresent areas of experimental work, thus not only directingresearch to defined questions, but also reducing practicalwork and time periods typically combined with productdevelopment. The identified four areas of future basicresearch will be discussed in the following.(a) Materials and their propertiesCeramics now cover an extensive area of functionalities.Hardly any other class of materials offers such a variety ofcrystal structure microstructure component10 -10 10 -9 10 -8 10 -7 10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 10 0 mnatural sciencematerials scienceengineeringbasic researchapplicationFig. 1.7. Hierarchies of length scale and multidisciplinary character of materials.mechanical reliability of ceramic parts. This would decreasethe material’s susceptibility to environmental stressesand facilitate integration of ceramics into whole engineeredsystems. In addition, as these tasks become moreand more interdisciplinary, advances in ceramic materialswill benefit increasingly from closer cooperation amongmaterials scientists, physicists, chemists, engineers, and,especially, biologists.properties useful for applications. Promising technical developmentsemerge from the discovery of new compounds,and new materials with specific functions have recentlyappeared on the horizon. These materials include hightemperaturesuperconductors, ultra high-strain single crystalpiezoelectrics, high-frequency dielectrics, phosphors,intercalation compounds, ductile layer-structured ceramics,and thermoelectrics. Detailed basic research in solidstate chemistry and solid state physics (i.e., activities fo-

cused on the elaboration of new compounds and the understandingof their basic properties) will continue to widenthe scope of materials, resulting in the optimization of existingmaterials’functionalities and the likely enhancementof ceramics with new physical behaviours. Since both resultin complex materials, there will be a continuous needfor the comprehensive evaluation of the underlying materials(i.e., structure analysis and phase studies of multicomponentsystems). Therefore, extended investigationsof physical, chemical, and mechanical properties will benecessary in order to evaluate the potential of the materialsfor practical applications. Of special interest will be the investigationof nanosized effects onto certain properties (i.e.,continuous or discontinuous property changes with sizedecreases and completely new physical behaviours).In the area of ceramic materials, ferroelectric ceramics aretechnically the most important. They are known for theirunique properties, such as high dielectric permittivity aswell as high piezoelectric constants, and are used in multilayercapacitors or as microwave devices within wirelesscommunication systems. Besides that, they will very likelyplay a key role in the future of information technology as abasis for low-cost, low-power energy consumption, highdensitystorage, and fast readout of information. Most ofthe inorganic materials for linear and nonlinear optics arealso ferroelectric. Infrared absorption, pyroelectricity, acousto-opticalactivity, second-harmonic generation, electro-opticalmodulation, and photorefractivity are optimizedin ferroelectrics because of their strong linear andnonlinear polarizabilities. However, the increasing powerand speed of today’s lasers has a large effect on the crystallinequality and defect content of ferroelectrics. This iseven more crucial in the case of integrated devices forwhich optical density, electric fields, thermal gradients,and mechanical stresses are increased by the limited sizeof wave guides.Ion conduction also provides great technological benefits.It is a basis for energy and information technology systemssuch as batteries, fuel cells, chemical sensors, and chemicalfilters providing efficient and cleaner energy transformation,chemical control, and environmental protection.Apart from the functional aspect, the application of thesematerials requires the simultaneous fulfilment of manyproperties. These include thermal stability, chemicalstability, mechanical stability, and electrical stability. Examplesin which fundamentals led to new materials anddevices are stable proton conductors, interfacially controlledionic conductors, and chemical sensors for acid/base active gases.In the field of high-temperature superconductivity, importantprogress has been achieved over the last few years regardingboth energy applications as well as electronics.Large-sized demonstration prototypes of superconductingcables, transformers, and fault-current limiters have beenfabricated and successfully tested. Some products, suchas current leads for low-temperature systems and filtersfor mobile telephone base stations, have already been introducedinto the market in a competitive way.Characterized by a steady increase in energy densityimposed by phenomenal requirements in the thermal managementof last-generation integrated semiconductordevices, highly thermal conductive materials represent amore important class of functional ceramic materials.There is much room for development in basic research, notonly in functional materials, but also in structural materials.Superhard materials for cutting tools, abrasives, andtribological applications, as well as thermal barrier coatingsto improve gas-turbine efficiency, and fibre-reinforced ceramicsfor failure-tolerant high-temperature components,are just a few examples of great technological importance.MATERIALS: SCIENCE AND ENGINEERING29Presently, piezoelectric ceramics certainly show the broadestrange of individual applications, including sonars, ultrasoniccleaners, buzzers, accelerometers, hydrophones, surfaceacoustic wave filters, delay lines, piezotransformers,ultra-precision positioners, and many other sensor and actuatorfunctions requiring a wide field of interdisciplinaryresearch for further evaluation.Magnetoresistive materials, which change their electricalresistivity upon application of magnetic fields, have alsoreceived attention for magnetic reading heads. Ceramics,such as doped rare-earth manganites (in which so-calledphenomena of colossal magnetoresistance were observed)exhibit extremely high values for this effect, even superiorto that of giant magnetoresistant metals presently in use.A unique set of properties is exhibited by a newly identifiedfamily of ternary-layered hexagonal carbides andnitrides (e.g., Ti 3 SiC 2 ). These ceramic compounds aremalleable at room temperature and deform plastically atelevated temperatures. They warrant further research.Other important classes of ceramics to be studied both forfunctional as well as structural applications are negativeandlow-thermal expansion materials such as beta eucryptite,sodium zirconium phosphates, vanadates, and tungstates.There is a widespread need for these materials inapplications that require either dimensional stability orthermal-shock resistance as well as in electronic devices,mechanical parts, catalyst supports for automotive applications,high-performance optical mirror substrates, ceramic

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART30hosts for nuclear waste immobilization, port liners for dieselengines, and coating materials for C/C composites.(b) Processing and microstructural designCeramics are synthesized into glasses, polycrystals, andsingle crystals, and many forms dictated by their use, includingfine powders, fibres, thin films, thick films, coatings,monoliths, and composites. Polycrystalline componentsare conventionally produced by powder synthesisand forming processes followed by sintering at high temperature.The performances of ceramic materials are determinednot only by the structure and composition, butalso by defects (such as pores), second phases (which canbe deliberately added to facilitate processing), and interfaces.Thus, one of the primary limitations of current ceramicprocessing technologies is that they are an art as wella science. This situation is changing progressively. For instance,in order to meet the requirements of miniaturizationand integration, these techniques have to be supplementedby deposition techniques, such as physical vapourdeposition (PVD), pulsed-laser deposition (PLD), chemicalsolution deposition (CSD), and chemical vapour deposition(CVD). During these processes, the materials aresynthesized on a microscopic scale without powder processingas an intermediate step, usually at temperaturesmuch below the typical sintering temperature of bulkmaterials. Not only can ceramic materials of small dimensions(e.g., the size of semiconductor chips) then bedeposited, thus responding to the integration needs ofdifferent materials, but their ceramic compositions andstructures can also be designed much more flexibly. Theunderstanding and mastering of phenomena at the microscopicand, more importantly, at the nanoscopic scalesclearly need further basic research. A specific example canbe found in thin films of ferroelectrics, where dielectricproperties are dominated by interfacial effects rather thanby the bulk capacitance.A great challenge is the architecture of ceramic materialsin atomic dimensions, not only in thin films but also in thickfilms and bulk materials. The ceramic materials will openup novel classes of materials with properties still unknownwith respect to conventionally processed materials. Onepossibility for research is the thermally induced transformationof preceramic compounds by solid state thermolysis(SST). By tailoring the composition and molecular structureof precursors by means of advanced chemical syntheses,and by controlling thermolysis, the composition,structure, and microstructure of ceramic materials can bedesigned. The characteristics of precursor thermolysis, andthe relative ease with which various geometries can be processedat the preceramic stage (such geometries includefibres, thin films and coatings, infiltrates, bulk materials,etc.), using standard polymer processing techniques,makes them highly applicable for the production of fibrereinforcedcomposites, oxidation-resistant coatings, wearresistantmaterials, and many others.Another growing field of research with an attractive technicalpotential is the production of materials inspired bybiomineralization. Oxidic deposits from aqueous solutionson organically modified surfaces, for example, provide asynthesis route for ceramics at ambient conditions. Suchtemplate-induced and self-assembled materials using biomimetictechniques provide “soft,” low-cost routes, offeringreal opportunities to get new metastable materials thatpossess original microstructures as layered polymer-ceramiccomposites and cannot be obtained by conventionalhigh-temperature routes. Therefore, the investigation ofinteractions between organic and inorganic phases, as wellas nucleation and growth phenomena, is a promising areaof basic research.Nevertheless, conventional elaboration processes will continueto offer breakthroughs. A deeper understanding ofthe surface chemistry of powders will lead to a better controlof the interaction between particles during colloidalpowder processing, thus providing a means for controllingpowder consolidation and defect-free microstructure.New methods for net-shape forming based on the controlof interparticle forces in dense suspensions of powdershave been proposed recently. There is no doubt that possibilitiesoffered by surface chemistry are far from beingfully exploited, especially in the case of nonoxide ceramics.Among the challenges for future years is the developmentof processing paradigms for the production of finerpowders, which could lead to new applications resultingfrom different green-state architectures.Direct and indirect cost savings by process-cost reductionsand product improvements, respectively, are necessary inthe field of advanced properties of ceramics. Cost savingsare typically achieved by a better understanding of the fundamentalsof the underlying processes. Savings could alsobe obtained by new types of low-cost processes, componentdesign changes or simplifications by using proper joiningtechniques, or product-development time reductions(e.g., by rapid prototyping). In essence, processing scienceremains a net priority, but in the case of ceramics, it nowextends far beyond the simple processing of powders.(c) Miniaturization and integrationOne of the great challenges and opportunities in advancedprocessing lies in the miniaturization and integration ofdifferent classes of materials (e.g., ceramics, metallic alloys,polymers). Miniaturization requires a search for new

processing techniques adequate for the manufacturing ofminiaturized components and devices, but also a propermeans to control microstructure at the mesoscopic level.A new field of research emerges as many characteristicsreveal side effects at the mesoscopic dimension. For instance,the properties of thin films and nanostructuredmaterials often deviate from those of corresponding microstructuredbulk materials.Modelling &MaterialElementsCompositionStructureMicrostructureMorphologySynthesisProcessingPropertiesTestingReliabilityFunctional & StructuralPerformanceLifetimeRecyclingComponentSimulationFig. 1.8. Modelling and simulation in material science and engineering.Due to miniaturization, nanosized effects and nanotechnologieswill thus gain importance. The miniaturized devicesmay include ultrathin films, multilayers, interfacecontrolled materials, nanocomposites, metastable systemswith high information content on the nanoscale, and lateralnanostructuring. Therefore, miniaturization provides aninnovative means for system development.Furthermore, present challenges to technological developmentoften lie in engineering the miniaturized devices.Integration of different ceramic materials with metals orfuture polymers is one way to miniaturize systems and toproduce one “function” for both functional and structuralapplications. Integration will thus play an increasing rolein many technologies. In the case of microelectronics, forexample, driving forces are the integration of various functionsinto conventional semiconductor chips and the evolutionof multifunctional components and systems. Thearea of integration would benefit from a clear understandingof effects that occur during the co-production of differentmaterials in a single device, and also of the roleplayed by interfacial chemistry in adhesion and fracture.Concerning microelectromechanical systems (MEMS)all scientific background of mechanical behaviour mustbe revisited for two reasons: (1) classical fracture mechanicsmay not be appropriate at the microscale when the sizeof the component approaches grain size; and (2) the validationof the design will require new testing methodologiesfor strength, toughness, fatigue resistance, etc.(d) Modelling and numerical simulationModelling and simulating have been used for a long timein the development and improvement of materials. On onehand, atomic dimensions have been successfully describedby, for example, first principle and ab initio quantum concepts.Fundamental theories exist for many physical phenomena(e.g. elasticity, plasticity, fracture, thermodynamics,electricity, magnetism), all of which improved enormouslythe understanding of materials. On the other hand,there have been developed a variety of chemical continuumconcepts and macroscopic finite element methods tosimulate the behaviour of materials and compounds. Bothareas have created much progress in materials science andtechnology (See chapter 4). However, in order to achieve areal breakthrough in designing new materials and tailoringtheir properties, there is a need to bridge both areas. Themost desirable breakthrough would be to outline the structuraland functional performance of a material directlyfrom its elemental composition, structure, and morphology(Fig. 1.8). Modelling concepts, which cover a completesequence from the state of matter (via material synthesisand processing) to a component’s properties and performance,would be the most desirable in materials scienceand engineering.1.2.3.4.ReferencesWerkstoffe, die die Welt verändern, by F. Aldinger, Physikalische Blätter55 (1999) 31.Fundamental research needs in ceramics, by Yet Ming Chiang and KarlJakus, NSF workshop report, (April 1999).Ceramics into the next millenium, by R.E. Newnham, Proceedings of theBritish Ceramic Society, 60 (1999) 3.Synergy ceramics project (1 st stage 1994-1998 and 2 nd stage 1999-2003),Fine Ceramic Research Association, Tokyo, Japan.MATERIALS: SCIENCE AND ENGINEERING31

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART321.3. Advanced Ceramic Materials: Summary of Possible ApplicationsG. Fantozzi | D. Rouby | J. Chevalier | P. ReynaudGEMPPM - UMR CNRS 5510 - INSA de LYON, 69621 Villeurbanne Cedex, France1.3.1. IntroductionCeramics, which exhibit very specific properties and cannotbe replaced by other materials, play a significant rolein the performance of numerous devices and equipments.In order to tailor a device property to its function, a goodknowledge of the correlation between property and microstructureis required. Because the microstructure dependson the processing route, ceramic processing methods aredecisive factors in developing the ceramic market.While current ceramic applications are well known, scientistsin the field continue to develop novel processing methodsthat can produce components of a complex shape andhigh reliability with a minimum of machining and at a lowercost.1.3.2. State of the ArtThe current status of research and development concerningmaterials and composites has recently been described[1-4]. In this chapter, we focus on areas of emphasis fornew materials, new applications and areas for application,and new processes.Many new materials are worth further examination, someof which are mentioned below:• Research activity in inert or active bioceramics has beensignificant and will have an effect in the medical andhealth fields, prompting new actions for the future.Abrasives for cut-off or grinding wheels and cutting toolsfor metalworking are important for industrial applications,and not enough research is dedicated to these materials.Therefore, hard and superhard ceramics are worthstudying more extensively.• Methods for studying the high-temperature behaviourof particle filters, corrosion behaviour in particular, needimprovement. Decomposition of SO x and NO x , pollutantsresulting from the combustion process, must berealized through catalytic reduction at low temperature.• Ceramic membranes are very useful for liquid (water) orgas hyperfiltration at a molecular scale.• Electroceramics have a wide range of applications andcorrespond to significant research activities in the fieldsof ion-conducting ceramics (such as batteries and sensors),electrical insulators (substrates and multilayer integratedcircuit packages), semiconductors (sensors),and superconductors.• Ferroelectric ceramics are very promising for many applicationssuch as capacitors, sensors, piezoelectric transducers,electrooptic devices, and thermistors, giving riseto productive research activities.• Ferromagnetic ceramics play a significant role in the electronicsindustry, and their applications are extensive, includingrecording, telecommunications, televisions, andelectronics.• Miniaturization for electroceramic components and devicesmust be a priority for the future.Chemical, physical, and mechanical characterization techniqueshave been suitably developed for materials applications.Using these tools, we need to explore new areas ofmaterials application, some of which are listed below:• In transport, catalyst supports for purification of automobileexhaust fumes are now finalized, but particle filtersfor diesel engines need further investigation to takeinto account corrosion problems. The monolithic or fibre-compositeceramic brakes for trucks, trains, planes,and automobiles require further development in termsof lifetime, cost, and performance. The use of other components(such as valves, seals, turbocharger rotors, camrollers, tippers, etc.) is actually limited because of costand reliability problems. Components for gas-turbinepower generators have to be improved. Major efforts arebeing made to develop a high-efficiency solid oxide fuelcell.• For energy production, several routes using coal, gas, ornuclear fuels are being considered. The performance ofcoal plants are limited by the thermomechanical andchemical behaviour of refractories, and a better knowledgeof this behaviour is needed. Improvement of combustionturbines requires an improvement in the behaviourof used ceramics, the use of more efficient thermalbarrier coatings, and a decrease in cost. The problem ofhow to clean up radioactive waste from nuclear powerplants must be solved. Environment factors to take intoconsideration include type and quantity of waste, healthrisks, level of pollution, and route of contamination

(soil, water, air). Fibres, whiskers, chromium oxide, andsmall particles can be carcinogenic, and substitutesmust be found.• The building industry has a significant influence onpeople’s lives and more emphasis needs to be placed onresearch. Materials that are important include cements,concretes, gypsum cements, roof tiles, and bricks. Traditionalceramics are used throughout industry, but theirdevelopment is hindered by the lack of interest in ceramicprocessing technology and its role in microstructureand properties. An area of growth is ceramic heritage,an application used to preserve and restore buildings,monuments, etc., which is interesting more andmore researchers.Compared to those of the U.S. and Japan, the EU’s fundamentalresearch activities have been quite effective in theareas of processing, bioceramics, ceramic matrix composites,carbon-carbon composites, cutting tools, nuclear ceramics,and electroceramics, but rather low regarding filters,building materials, refractories, fibres, gas turbines,abrasives, superhard ceramics, nanomaterials, functiongradient materials, and finishing.The EU, U.S., and Japan have different research strategies.In Japan, national projects with technological goals are definedand funded by the government. A similar approachfor some programmes exists in the U.S. In contrast, Europeanprojects are rather broad with less precise goals, butthere are national projects with more specific objectives.MATERIALS: SCIENCE AND ENGINEERING33Several processing methods are well developed, includingthe characterization of powders, microstructure, and porosity;others need more attention:• Powder synthesis requires complementary studies, thepowder behaviour being fundamental for shape-formingprocesses and densification. Some shape-formingprocesses, such as pressing, slip casting, and tape casting,are well known. Sintering has been extensively studied,and there is a good understanding of the involvedmechanisms for ceramics. “Modelling” density variationduring pressing and shrinkage during sintering are neededin order to obtain near-net shape parts and to minimizemachining, which represents a large portion of thefabrication cost.• New routes for near-net shape forming of advanced ceramicsand composites have been developed and holdpromise for the fabrication of components with highreliability at acceptable costs.• Injection moulding offers great promise for low-cost fabricationbut needs more attention in the area of organicvehicle removal.• Pyrolysis of inorganic polymers can be used for the productionof ceramic parts, but this process results in significantshrinkage, which can lead to the introductionof flaws. Therefore, this route is promising but requiresfurther research concerning the synthesis of inorganicpolymers and the transformation of polymers to inorganicsolids.• Quality control methods for ceramic components arenot often studied. The area of nondestructive techniques,in particular, needs more attention.1.3.3. Trends for the FutureThe socioeconomic impact of the following themes willbe taken into account in establishing priority actions andbasic research necessary to reach fixed objectives whichare summarized in Table 1.1 and 1.2.(a) New materials, devices, and applicationsThe following are considered priority actions:i) Bioceramics: application to health Today’s orthopaedicimplants have an average life expectancy of 10 to 15 years,which is generally limited by osteolysis, which is causedby the wear of polyethylene cups against metal or ceramic(i.e., alumina- or yttria-stabilized zirconia) femoral heads.However, considering our aging population, there is a growingdemand for implants with a life expectancy of more than30 years. They must include new generations of ceramicceramicwear couples for hips, and knee prostheses thatcan last where ceramics have so far failed.Therefore, existing ceramics must be improved in terms ofreliability (resistance to slow crack propagation for alumina-basedmaterials and stability, and in particular for zirconiaceramics, which presents a problem for surface lowtemperaturedegradation). When working on ceramic processing,scientists must strive to refine microstructure (colloidaland sol-gel) processes and increase ceramic stabilityand crack resistance. Ceramic processing must includethe ability to make complex shapes (i.e., knee prostheses)with high reliability. We must incorporate new ceramicmaterials into orthopaedic design. They must addresscurrent biocompatibility problems and have propertiessuperior to monolithic alumina and zirconia. There is anew interest in the potential for the biomedical applica-

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART34tions of zirconia-toughened alumina. Materials scientistsare already familiar with zirconia-toughened alumina,which is exceptionally hard, strong, and crack resistant.However, its superiority for joint prosthesis applicationmust now be proved by simulator studies under physiologicalconditions (where there is a need for knee prosthesessimulators and complex modes of fracture studies), industrialmanufacturing, and in vivo preclinic evaluation.Bioactive ceramics, mainly hydroxyapatites, are used todayas coating on femoral stems and acetabular cups for noncementedhip and knee joint prostheses. However, their usemust spread to other applications, such as bone substitutes.Most orthopaedic surgeons agree that synthetic bonesubstitutes sometimes result in clinical failure caused eitherby materials fracture or lack of bone integration. Thechallenge is therefore to tailor the microstructure and thecomposition (hydroxyapatite/tri-calcium phosphate composites)of bone substitutes to adapt to the biofunctionalityin a given site. Materials scientists should also workwith biologists and surgeons to better understand osteoconductionmechanisms to back-up processing. The secondgeneration of bone substitutes must be more active,incorporating medicines (e.g., antibiotics, chemotherapy,drugs) to act locally against disease. The third generationwill be the hybrid bone, where the ceramic is the supportto human cell culture. Basic research in bioceramics shouldfocus on producing complex shapes with high reliability,developing nanocomposite ceramics with improved properties,and incorporating medicines into hybrid bone.ii) Ceramics and environment The reduction of pollutants,an actual necessity, requires research work in thefollowing areas:• Particle filters: The corrosion behaviour must be improvedby acting on the ceramics microstructures, decreasingthe glassy phase amount, or changing the type of ceramic(oxide or nonoxide ceramic). Furthermore, filter materialsmust show good thermomechanical behaviour.• Development of a low-temperature catalytic reductionfor the decomposition of SO x and NO x pollutants.• Problems of refractories used in waste treatment plantsand treatment of flying ashes.• Development of new ceramic membranes for hyperfiltrationand nanofiltration of liquid or gas, often very aggressive,for desalination.• Nuclear waste treatment: vitrification, and cementitiousmaterials.• Ceramic recycling.• Development of antibacterial tiles, new sanitary wares,or smart toilets.Priority research in environment must be focused on catalyticreduction, filters, membranes, nuclear wastes, recycling,and antibacterial actions.iii) Nanomaterials and functional gradient materialsIt is expected that nanostructured ceramics play an importantrole in following areas:• Nanocomposites are known to exhibit unusual properties.Creep resistance, and thermomechanical or wearbehaviour can be improved by using nanocomposites.Nanocomposites or nanoceramics exhibit superplasticity,which can be used for shaping.• Nanostructured coatings on substrates allow increasedwear and corrosion resistance and durability of cuttingtools. The different processes used for obtaining nanostructuredmaterials and nanomaterial behaviour mustbe investigated further.• Carbon nanotubes show exceptional mechanical andelectronic properties, and can be very high-performancematerials. This new class of materials merits greater attention.• Functional gradient materials reduce thermal stressesfor thermal barriers and can be used in a number of applications,including thermal insulation, thermal fatigue,oxidation and corrosion resistance, and electrical, magnetic,or optical properties. Research activity in functionalgradient materials (processing and properties) mustbe encouraged.• Superhard ceramics are interesting materials, but researchin this range is insufficient.• Ceramic-ceramic and ceramic-metal joining is importantfor the production of complex structures and requiresfurther development.Preferably, research in nanomaterials should focus on nanostructuredcoatings and carbon nanotubes.iv) Electroceramics Electroceramics are subject of broadinterest to the research community. The following are someof the areas of electroceramics that merit increased attention:piezoelectric actuators; hybrid sensors; electrooptic devices;new ferrites; resistors; positive temperature coefficientmaterials; materials for batteries, fuel cells, and electrochemicalcapacitors; oxygen separation membranes;transport properties; and defect chemistry.Research in the following areas must be developed:• Nanopowders, nanoelectroceramics• Decrease of the sintering temperature• Multilayer structures: reduction of thickness,substitution of noble metals• Decrease of the mechanical and dielectric loss at veryhigh frequencies

R & D tasksSocio-economic impact• Microstructure and compositiontailoring• Corrosion• Science of interfaces• Miniaturization• Modelling• Low cost• Removal of organic vehicle• High reliability• ModellingNew materialsBioceramicsFilters and membranesNanomaterialsElectroceramicsNew processesNear net shape formingInjection mouldingGreen machiningSelf-propagating hightemperature synthesis• Health• Environment• Structural andfunctional ceramics• Wireless technologies• Complex shape parts• Structural and functionalceramicsMATERIALS: SCIENCE AND ENGINEERING35• Life-time(fatigue, oxidation)• Reinforcement• Recycling• Repairing• ModellingNew applicationsThermostructural composite partsBrakesRefractoriesNuclear wastesBuilding and traditional ceramics• Aerospace• Environment• Energy• Transport• Metallurgy• Everyday life• HeritageTable 1.1. The socio-economic impact of ceramic materials.• Development of sol-gel technology for thin layers• New ceramics with improved properties• New processing routes• Miniaturization of components and devices for wirelesstechnologiesIn the area of electroceramics, particular attention must bedevoted to sensors, actuators, electro-optic devices, superionicconductors, ferrites, nanoelectroceramics, multilayerstructures, and miniaturization in relation to new processingroutes.The science of interfaces is multidisciplinary and useful fora wide spectrum of applications, such as electroceramics,functional gradient materials, joining, thin films, and coatings,and therefore needs more research, particularly inthe areas of miniaturization and nanomaterials.(b) New processesA significant challenge in ceramics concerns the fabricationof complex-shaped components without defects (pores,inclusions, inhomogeneities, etc., which increase the riskof failure), with high reliability and low cost. Because machiningis expensive, it will be important to develop andoptimize near-net shape forming of ceramics, which allowsminimizing of fabrication time, a primary competitive factor.Processing routes requiring more research include:• Injection molding: This process needs a large amount ofbinders that must be removed without leaving flaws.• Colloidal techniques: Direct coagulation casting, gelcasting, and hydrolysis- assisted solidification, whichneed a high amount of additives.• Solid freeform fabrication.• Temperature-induced forming: Consolidation of a slurryis obtained by a temperature increase, and shaping ismade by using a nonporous mold.• Directed molten metal oxidation or reactive melt penetrationfor composites processing.• Self-propagating high-temperature synthesis is an interesting,low-cost technique for making fine powders.• Synthesis and processing of nanomaterials and nanocompositesare exciting areas to be developed.The machining of sintered ceramics is time and energyconsuming and can represent up to 80% of the productioncost of a ceramic part. A possible route to reduce machiningcosts is to machine green ceramics, which can be aneffective way to obtain complex ceramic parts. However,research in this field is sparse and needs to be developed.It is critical that the research community investigates thetypes of green properties required to withstand green machining.The role of binders must be specified, and specificmechanical tests for green compact characterization mustbe developed in order to find the correlation betweenmechanical behaviour and green machine performance.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART36Basic research in processing must be devoted to near-netshape forming, organic removal, SHS synthesis, and nanomaterials.(c) Other applicationsi) Fibre-reinforced ceramic composites Ceramic matrixcomposites reinforced with fibres (CMCs) are devoted tohigh-performance thermomechanical applications withoutthe brittle fracture behaviour typical of conventional ceramics.For the future, the main obstacle concerning thesematerials is still costs of both, raw materials and manufacturing.In addition, several properties (such as oxidationresistance, creep, and fatigue) have to be improved. Researchmust be developed in the following directions:• Reinforcement: There is a need for cheaper fibres withimproved creep resistance. The best SiC fibres are veryexpensive and exhibit extremely high creep and oxidationrates. Oxide fibres, like alumina, are limited becauseof very high creep rates. Carbon fibres need improvedoxidation-protection solutions.• Protection against oxidation: Development is needed ofsophisticated multilayer matrices and multilayer surfacecoatings in order to promote the matrix cracks healing byformation of glasses in the whole temperature range. Researchin this field must be done in close relation withprocessing solutions. Brake materials (carbon-carbon orother systems) need research in a similar direction, withparticular attention to the effect of the inhibitors on frictionperformance.• Reliability of inhomogeneous, anisotropic, and porous materials:Development is needed of adapted nondestructiveexamination methods, specific strength and qualitycriteria, and new damage indicators. Despite the effectivereduction in brittleness caused by fibrous reinforcement,further research is needed to improve toughnessand thermal and mechanical shock resistance. This is particularlytrue in light of the goal of cheaper materials.ii) Refractories Refractories are largely used in industryiron,steel, metallurgy, foundry, cement works, glass, ceramic,power plants, chemistry, etc. These materials playan important economic and strategic role, and the improvementof their performance constitutes a major challengefor the future. Traditionally, rather empirical methods wereused to improve refractories’ behaviour, but it is now verydesirable to forecast and model microstructures and propertiesof refractories.We must encourage the study of the microstructurepropertyrelationship, modelling of the thermomechanicalresponse, and corrosion behaviour and apply our results toreal components.iii) Building materials Because the use of cement requireswater consumption, the availability of water is critical. It istherefore necessary to improve the workability of concretein order to reduce water consumption. Macrodefect-freecements with organic additives have more strength and lowerporosity than conventional concrete. Cement strengthcan be increased by fibre reinforcement. Recycling fly ashesand other light aggregates in concrete must be encouraged.The ability to use cement for repair or reconstructionnow needs to be taken into account. The temperature behaviourof cement and concrete also needs to be studiedand improved for public safety in tunnels, buildings, andother public structures.Research on cement, concrete, and plaster must receiveincreased attention. Specifically, the following areas needbasic research: self-healing composites, fibres, interfaces,corrosion, recycling, and new concretes.In conclusion, new developments in ceramics require bothbasic and applied research in materials and properties, processingand microstructure, and design and modelling ofmaterials and devices. The trends for the future are summarizedin Table 1.2.1.2.3.4.Needs in basic research for ceramic materials• Near net shape forming• Processing of complexshapes with high reliability• Hybrid bones• Catalytic reduction• Membranes• Nuclear wastes• Recycling• Antibacterial actions• Nanopowders• Carbon nanotubesReferences• Nanomaterials and nanocomposites• Nanostructured coatings• Sensors• Electro-optical devices• Superionic conductors• Ferroelectrics• Miniaturization• Multilayer materials• Interfaces• Self healing compositesTable 1.2.R. Pampuch, Constitution and Properties of Ceramic Materials, Elsevier,Amsterdam (1991).D.W. Richerson, Modern Ceramic Engineering, Marcel Dekker, New York(1992).R.J. Brook, Concise Encyclopedia of Advanced Ceramic Materials, PergamonPress, Oxford (1991).R.W. Cahn, P. Haasen and E.J. Kramer (ed.), Materials Science and Technology,Vol. 11 Structure and Properties of Ceramics, Vol. Ed. M. Swain(1994), Vol. 17A and B, Processing of Ceramics, Parts I and II, Vol. Ed. R.J.Brooks (1996), VCH, Weinheim.

GeosciencesBiosciences1.4. Inorganic MaterialsJ. Etourneau | I.C.M.C.B.-UPR CNRS 9048, Université de Bordeaux, 33608 Pessac, FranceContributors:A. Fuertes (Institut de Ciencia de Materiales de Barcelona,CSIC, Barcelona, Spain), J. Lucas (Université de Rennes,Rennes, France), C. Sanchez (Université de Pierre et MarieCurie, Paris France).1.4.1. IntroductionAll solids, whether natural or synthetic, are materials.However, when we speak of the science of materials, weare speaking of the relationship between structure andSolid State Chemistry, Materials Chemistry,and Solid State Physics< Molecular and Lattice Engineering >• Structures• Nanostructures• Microstructures• DefectsPropertiesModellingSynthesisFromExploratoryResearchproperties such that structures can be selected andconstructed to have the desired properties. This definitionencompasses inorganic as well as molecular materials.The preparation and examination of new solids have led totechnological advances as well as enormous progress inour understanding of materials properties. We now knowthat the behaviour of ions, atoms, and molecules withinvarious types of solids can be (and usually is) drasticallydifferent from the behaviour of the same species as individuals.This is somewhat analogous to the behaviour ofhumans as members of various groups (ranging from aninformal company at a party to a well-organized sports teamor military detachment) and as solitary “individuals.”Over the last thirty years, chemistry has made an increasinglyimportant contribution to the science of materials,so much so that the terms “solid state chemistry” and“materials chemistry” (which includes inorganic andmolecular materials) have come into being.The guiding principle for all fields of study in materialsscience is that the selected function defines the material,and each of these fields of study requires a multidisciplinaryapproach, ranging from fundamental research tocreation of the final product (Fig. 1.9). The main goal ofthis chapter is to show the state of the art, visions, breakthroughs,and research needs in three basic complementarymaterials science research fields:MATERIALS: SCIENCE AND ENGINEERING37Materials Science and Engineering• Processes• Treatment, Transformation, and MaterialsPreparation into different Morphologies• Test of Properties and Performances• Performance Evaluation in Service• Choice and QualificationMaterials Technology• Industrial Development and Production• Integration within Devices• RecyclingFig. 1.9. Selected functions define the material.To FinalProduct• Inorganic solid state chemistry and materials chemistry• Inorganic molecular chemistry• Inorganic amorphous solids (glasses)1.4.2. Inorganic Solid State Chemistry and MaterialsChemistryInorganic Solid State Chemistry provides the backgroundneeded for fundamental chemical research to improve existingmaterials and provides the basis for the discovery ofnew materials through the use of chemical and physicalchemicalconcepts (e.g., structure, chemical bonding, etc.)at the atomic scale. Lattice engineering chemistry couldbe synonymous with solid state chemistry. On the otherhand, materials chemistry is a research field concerned

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART38with understanding and controlling functional condensedmatter from a chemical perspective. Solid state chemistry,materials chemistry, condensed matter physics, and engineeringconstitute the main components of the multidisciplinarymaterials science research field.(a) State of the artSolid state chemistry has two well-defined faces: a staticface, which is the determination and description of theproperties of a given material in terms of geometrical structure,electronic structure, chemical bonding, and physicalproperties; and a dynamic face, which describes any kindof time-dependent structural, compositional, or electronicreorganization in materials, in particular reactivity, as afunctional property of chemical systems. In the area ofsolid state and materials chemistry, considerable progresshas been achieved in the understanding of the correlationsbetween structure, bonding, and physical properties. However,understanding the most important relationship – theone between these static parameters and the dynamicaspects (the reactivity of solids) – is far less developed.Chemical bonding in solids is not completely understood,mainly because of the wide variation in elemental chemicalproperties. Many difficult challenges remain in predictingthe composition, structure, and properties of newmaterials. Consequently, the synthesis of novel solids is asmuch an art as a science. (It should be noted that the discoveriesof new compounds and structure types highlighta versatility that nature has allowed with a relatively smallnumber of elements.)Research in the field of inorganic materials chemistry duringthe last decade has been mostly directed towards veryrelevant developments in some groups of materials. Importantdiscoveries concern high-T c superconductors, thefullerenes C 60 and C 70 (and related carbon or inorganicfullerides), colossal magnetoresistant manganese oxides,and mesoporous solids with catalytical or adsorbent applications.In addition to these discoveries, which have led toa vast number of articles published in the most prominentjournals of the field, the following should also be highlighted:fast ion conductors and battery materials, hybrid materials,biomaterials, and dielectric and optical materials.Fundamental inorganic materials chemistry research mustbe concerned with the following three goals: (1) the developmentof synthetic methods to prepare novel compoundsor to improve their properties, (2) the discovery of newphases with desired properties from crystal chemical criteria,and (3) the full characterization of new phases froma chemical and structural point of view.Over the last thirty years, Europe has had an impressiverecord in the sciences, winning Nobel Prizes in both chemistryand physics. During this time, European solid statechemistry and physics have acquired an internationalreputation because of consequential contributions in thedomains of, most particularly, magnetism, superconductivity,theory of metals and semiconductors, organic conductorsand superconductors.For the past twenty years, the fields of solid state chemistryand physics have grown together. Researchers fromboth disciplines have tried to establish a common languagethat not only defines a material in terms of its structure,composition, defects, and morphology, but its physicalproperties as well. Competition among countries has infact brought collaboration between the two disciplines,specifically collaboration between the earlier discipline ofmaterials for optics, optoelectronics, and electronics, andthe more recent discipline of superconductors with a highcritical temperature. In a similar way, the recent emergenceof the nanosciences (influenced by trends in chemistryas well as physics) has brought to light the complementaryrelationship that exists between physics andchemistry.Europe still holds the international standard in solid statechemistry and physics, mainly because of its strong emphasison both education and research. The United States,influenced by educational institutions in France and Germany,has not yet achieved its potential for leadership insolid state chemistry, particularly in the realm of education.Japan, known for its mastery of materials technologyand the transformation of fundamental discoveries intoproducts, compensates for lost time in basic researchthrough its achievements in solid state chemistry and molecularsciences.A fundamental difference between Europe and the U.S.and Japan exists in the influence of industrial groups (suchas Dupont de Nemours in the U.S. and Hitachi in Japan)on the global effort in basic research in materials. It shouldalso be noted that in the past few years, this corporateinfluence has strongly been reduced but nonethelessremains significant. The U.S. and Japan have recentlylaunched very important nanotechnologies researchprogrammes, which includes nanomaterials. China andKorea have kept pace with Europe, the U.S., and Japan inthe fields of solid state and materials chemistry. (It shouldbe noted that the French School of Solid State Chemistryand Physics has formed an alliance with a group ofresearchers from Asia.)

The countries of the Central European Initiative (CEI),including Russia, are more oriented towards materials science(e.g., processing, shaping, etc.), but have not yetreached the level of Europe, Japan, the U.S., China, andKorea in solid state chemistry. However, Russian researchersdo play a primary role in solid state physics. Unfortunately,despite progress in these scientific areas, the politicaland economical problems that the countries of the CEIare facing today will certainly impede their developmentin the disciplines of materials science and solid-statechemistry.In Europe, France, Germany, and United Kingdom are atthe same level of materials science development. In fact,two large industrial groups are strongly involved in thesecountries’materials science research effort. Spain and Portugal,however, lack behind France, Germany, and UnitedKingdom. Denmark is a notable contributor to solid stateorganic chemistry. Italy is active in the field of solid statephysics, particularly regarding spectroscopic studies.Europe has a problem with the valorization of its ownresearch within the European Community. Too manyforeign products and technologies are resulting from basicresearch undertaken in Europe, in France particularly, andthen these products are in turn sold in Europe. Japan forinstance, is buying the knowledge from Europe at adecreasing rate due to the progress of its own fundamentalresearch. However, it continues to sell the products it hasproduced with this knowledge in Europe. Europe, on theother hand, buys both knowledge and products. This willultimately adversely affect the development of research inEurope. We need to decrease both the amount of foreignknowledge we buy and products we sell. Research in Europecould continue to develop if downstream researchsectors could find tangible ways to meet the needs of thepublic. It will be necessary to distinguish between a valorizationof knowledge and a solution to scientific and technologicalproblems confronted by industry in the developmentof a product, process, or technology.To solve this problem, researchers must convince the publicthat it is possible to design a product or a process that iscost effective without compromising its state-of-the-artproperties (e.g., ability to be recycled, nonpolluting),although cost is not always associated with status. In addition,academic laboratories must help researchers by makingavailable database banks of basic knowledge in orderto solve the problems raised by the industry.(b) Future visions and expected breakthroughsOne of the great challenges in solid state chemistry todayis the design and synthesis of novel inorganic solids possessingdesired structures and properties. A main focus areais the creation of a suite of tools to predict the stabilityand properties of a given inorganic network from first principles.Unlike the highly developed field of organic synthesis,solid state chemistry lacks such tools.To pursue this objective, researchers first need to investigatereaction mechanisms in solid state chemistry synthesisin order to determine the principles that will be thebasis for the discovery of unknown materials. It would beadvisable to increase the strong collaboration betweentheoretical activities and experimental efforts for predictingthe chemical stability of novel phases and adjustingcrystal chemical variables in order to get a desirable physicalproperty. Future research should also study methodsfor improving existing and new materials to gain a betterunderstanding of the mechanisms responsible for physicalproperties.i) In optics The future of materials is found in five maindomains: phosphors, scintillators, lasers, and materials fornonlinear optics and colour pigments. The discovery of newmaterials remains tightly connected with, for example:• A better knowledge of the nature of absorbing centres,the states associated with charge transfers for phosphorsand scintillators.• The replacement of mercury-vapour luminescent tubesby tubes containing Xe (boosting research on phosphorsand identifying levels above 40,000 cm -1 , etc.).• The mastery of vibrational properties (reducing nonradiativetransitions).• The search for nonsolarizable monocrystalline densematerials with unalterable large dimensions, a highquantum yield, and a short lifetime (i.e., within a rangeof a few nanoseconds) of the level responsible for emissions,mainly for scintillators.• The search for doped crystals with wide absorptionbands for the purpose of compensating the temperaturedrift of laser diodes.• The search for “blue” starting from laser diodes emittingred for their application in optical reading.• The study of nonlinear properties (passive or active planaror cylindrical wave guides [with lasers]), includingthe origin of dielectric susceptibilities (2) and (3) inglasses and the origin of (2) in certain noncentrosymmetriccrystals. Questions to consider include: Are glassesreally lost materials for noncentrosymmetric effects?Can they be anisotropic at nano- or microscales? Searchfor glasses with elevated values of (3) for ultrafast commutation,etc.• Preparation of dense transparent ceramics for lasersources (IR, etc.).MATERIALS: SCIENCE AND ENGINEERING39

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART40• The search for new colour pigments (red to yellow) andanti-UV pigments.• The optical behaviour of nanometre-sized particles isnot well understood, even in common applications involvingluminescent, photochromic, and colloidcolouredproperties.Besides the necessity of a better understanding of defectspresent in single crystals and thin films and of the vitreousstate of matter, materials science would benefit from adeeper understanding of the ways in which the study ofglass-crystal composition (e.g., the development of vitroceramics)can enhance the development of composite materialsfor optics (nanograins –> optical nanocavities), theresearch for new materials, as well as composition andmorphology. Hybrid materials, such as organic/inorganic,deserve to be developed (by combining high polarizabilitiesof molecular entities with good thermomechanicalproperties of inorganic matrices).ii) In magnetism Several areas of magnetic materials researchneed to be explored. Research of new materials isrequired for permanent magnets, magneto-optical displays,reading heads, etc. A better understanding of themagnetic properties of surfaces and interfaces in multilayermaterials is also necessary. In addition, the mechanismresponsible for giant magnetoresistance in oxides andderived insulating materials is needs to be elucidated.On a very fundamental basis, it is necessary that the studiesof strongly correlated electron systems continue and new,well-characterized materials be prepared (e.g., the effectof the hybridization of 4f or 5f states with conduction electronson magnetic properties, superconductivity and theheavy Fermion systems, the Kondo “networks” that are stillpoorly understood, etc.). Furthermore, the possibility ofpreparing metals and alloys at the nanoscale should allowto address several unanswered questions, such as, whatmagnetic properties should one expect from a nanocrystallinematerial for which the fraction of surface atoms isvery high?iii) New materials for passive components (ferroelectrics,piezoelectrics, pyroelectrics, relaxors, etc.) This area ofresearch concerns the preparation of new complex materials(mainly oxides, fluorides, oxyfluorides, nitrides, or oxynitrides)in either stable or metastable form. In the case ofmetastable forms, the compounds can be stabilized as thinlayers thanks to the principle of the method itself, whichallows for a pronounced reactivity on the substrate at temperaturesthat are relatively low when compared to massivematerials.In addition to studies of thin layers and multilayer systems,the effort should also be aimed for bulk materials. As it isfor all structural and functional materials, the study of therelationships between composition, nanostructure, microstructure,and properties is mandatory for the understandingof the mechanisms, hence the need for optimizingmaterials.These fields of research are very tightly linked to applications:actuators (electrostriction, piezoelectricity), IRdetectors (pyroelectricity), and dielectrics for capacitors(e.g., replacement of Pb by other elements). The followingapplication areas require special attention:• Single crystals and wave guide for optics• Bulk ceramics, thick films, and single crystals forelectromechanical applications• Electroceramics using ferroelectrics• Thin ferroelectric films for microwave electronics• Integration of ferroelectric thin films on silicon for fieldeffect transistor (FET) or ferroelectric memories(FERAM)iv) Coupling of properties (smart materials) The associationof properties (e.g., piezoelectric, piezoresistive, metallic,superconducting, insulating, nonlinear conducting,magnetic, etc.) can be put to good use in granular and nanostructuredmaterials. The modelling of the association oftwo properties has been achieved without the actual existenceof relevant materials. For ternary nanocomposites, nomodelling exists at all and the materials are scarce.Similarly, studies on nanocomposites based on fullerenesand carbon nanotubes containing metals or superconductors(e.g., electrochemical deposit in nanopores created bythe ionic bombardment of a membrane of soluble polymer)should be developed.v) Superconductors In the framework of the present programme,research should focus on new compounds ratherthan those derived from oxygenated perovskites. This recommendationis clearly illustrated by the recent discoveryof the high-temperature (T c ~ 40 K) superconductivity of“metallic boron” in MgB 2 (J. Akimitsu, Symposium onTransition Metal Oxides, Sendai, January 10, 2001).vi) Conductors Three main classes of electronic conductorsshould be considered (other than metals and theiralloys):• Molecular crystals (new charge transfer salts, organiccrystals, certain oligometric systems, organic-inorganiccompounds, crystals derived from fullerenes). Synthe-

sis of new molecules must be encouraged, as well asmodelling of the electronic properties of such systems.• Nanostructures (molecular wire, carbon, or boron nitridenanotubes, etc.). This is relevant to a totally new domain,and the accent will be put on the research of modelsystems, on the comprehension and modelling of electronictransport at the nanoscale (which is intrinsicallymonodimensional), and on the development of techniquesthat allow such measurements to occur (bymeans of near-field techniques, particularly STM andAFM).• The oxygenated conductors for which the polaronic natureof the carriers is generally agreed upon but whichcontinue to raise many questions, such as those relativeto the role played by magnetic interactions in transportproperties (e.g., the effect of giant magnetoresistanceon transport properties) or the behaviour in the normalstate of superconducting oxides, one of the keys towardunderstanding the phenomena. New compounds shouldbe prepared and elaborated into single crystals or thinfilms (oxides, oxynitrides, etc.) in order to study physicalproperties.vii) Semiconductors In the next ten years, wide-gap semiconductorswill be developed: the III-V nitrides, GaN, AlNfor applications in optoelectronics (blue-violet laser), thewide-gap II-VIs (and to a lesser extent ZnSe), and “verylarge gap” materials and materials with exceptional thermalproperties such as BN, diamond C, and SiC. Ternaryand quaternary compounds are likely to possess interestingproperties, such as the effects of the variation of themagnitude of the forbidden band, which in a given systemcan go through a minimum as a function of the composition,the so-called “bowing” effect (e.g., GaN-GaAs).viii) Electrochemical energy storage and electrical energyproduction Today, electrochemical energy storage andenergy production concern batteries and fuel cells, respectively,for many applications (e.g, space, aeronautic andearth transportations, habitats, telecommunications, etc.).Inorganic solid state chemists, electrochemists, and materialsscientists are deeply involved in the search for newinorganic materials for applications such as positive andnegative electrodes or solid electrolytes in electrochemicaldevices.In the field of batteries, two areas can be distinguished bytheir applications: (1) microbatteries involving inorganicsolids (glasses and crystallized materials) for use in smartcards, flat self-powered displays, the healthcare sector,etc.; and (2) batteries for portable devices and electric orhybrid vehicles, etc. In the latter case, interfacial problemscan be solved by using a liquid – a gelified or polymericelectrolyte. The challenges are in the effort toimprove electrodes presently used and to search for newmaterials exhibiting high specific energy, rapid kineticexchange of the ionic species, and a long life (where composition,structure, and morphology of the materials aredirectly involved). In addition, understanding of electrochemicalreactions is also important because chemical reactionsoccur at all stages of battery use (cycling: calendarlife; ageing: shelf life) and lead to materials modificationsthat must be carefully identified in order to optimize thematerials.In the field of solid oxide fuel cells (SOFC), a great deal ofoptimism and enthusiasm in Europe that presentlyexists has resulted from the development of fuel cell technologyin the 1960s. The large NASA projects on fuel cellsfor the Gemini and Apollo space capsules stimulated otherfuel cell programmes, in the U.S., Japan, and elsewhere.SOFCs offer a clean, pollution-free technology to electrochemicallygenerate electricity at high efficiencies. Thesefuel cells roughly consist of an oxygen-ion conducting electrolyte,electronic or mixed electronic/ionic conductingelectrodes, and an electronic conducting interconnection.In addition to technological problems, there are other issuesto examine from a materials point of view. The mainobjective with SOFCs is to operate at the lowest possibletemperature (500-700°C) without compromising cell resistanceand electrolyte kinetics. The selected materialsmust fulfill the following conditions: (1) suitable electricalconducting properties required for different cell componentsto perform their intended cell functions; (2) adequatechemical stability at high temperatures during celloperation as well as during cell fabrication; (3) and minimalreactivity and interdiffusion among different cell components.As of today, yttria-stabilized zirconia (YSZ) andlanthanum manganite or ferrite are the materials mostwidely used as electrolytes and cathodes, respectively. Thechallenge is to search for (1) new electrolytes working atlow temperatures, and in this manner CeO 2 -based compoundsshould be promising; (2) and new cathodic materials.ix) Low (reduced) dimensionality materials Nanometricand mesoscopic materials (such as fullerenes, nanotubes,aggregates, nanoporous structures [e.g., silicon and clathrates,composite polymers, etc.]) that continually surpriseus by their properties (optical, electric, magnetic, etc.).They must be the topic of study for emerging (e.g., carbon,silicon, boron nitride, etc.) as well as future systems.MATERIALS: SCIENCE AND ENGINEERING41

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART42Likewise, new slab-like compounds should be investigatedfor their superconducting, magnetic, ionic conduction(cationic and anionic) and/or electronic properties. Weshould focus on their characterization, particularly the occurrenceof incommensurate structures.x) Materials and life sciences The scientific age intowhich we are moving is a revolutionary one. Biologists willbe able to create new forms of life that do not exist in nature(allowing them to identify genetic defects and eventuallycorrect them), and solid state chemists and materialsscientists will be able to create a vast range of new syntheticmaterials that are tailored to meet specific needs.Biologists, solid state chemists, and materials scientistswill be able to collaborate in two main domains: biomaterialsand materials in relation to healthcare, therapeuticsand diagnostics.Biomaterials – Bioceramics such as polycrystalline alumina,hydroxyapatite, partially stabilized zirconia, bioactiveglass, glass ceramics, and polyethylene-hydroxyapatitecomposites have been successfully used for the repair, reconstruction,and replacement of diseased or damagedbody parts, including bones. However, clinical success requiresthe simultaneous achievement of a stable interfacewith connective tissue and a match of mechanical behaviourwith the implant to be replaced. Research is continuingto develop new coatings that can be chemically bondeddirectly to the implant material and therefore induceappropriate protein-absorption behaviour so that bone celladhesion will occur and promote bone formation at thejunction site. In a similar way, resorbable biomaterials mustbe designed to degrade gradually over time in order to bereplaced by natural host tissue. To achieve these goals, wemust come to a better understanding of the interactions ofbioceramics with organic components on the molecularlevel.Materials in relation to healthcare, therapeutics, and diagnostics– Living systems are governed by molecular behaviourat nanometre scales where the disciplines of chemistry,physics, biology, and computer simulation all converge.Inorganic nanomaterials can be used in different areas as,for example:• Substrates for vectorizing (1) contrast-agent moleculesin order to improve medical imaging technology, and (2)drugs directly to their site of action by molecular recognition.• Substrates for biosensors in order to monitor bloodchemistry, local electric signals, or pressures. The sensorswould communicate with devices outside the bodyto report results, such as early signals that a tumour, heartdamage, or infection is developing. For instance, segmentsof DNA and other biomolecules can be attachedto the surfaces of silicon chips in predefined arrays. Thisis the basis of so-called “lab on a chip” technology.One of the main challenges will be to enhance the functionof inorganic magnetic nanoparticles or silica chips inorder to graft specific biomolecules.(c) Research needsResearch efforts need to favour synthesis innovation andmaterials elaboration within an integrated approach. Theobjective of a synthesis can be purely chemical (search fornew reactions, new phases) or devoted to materials exhibitingparticular properties that could be chemical (reactivity),physical, or biological. However, the synthesis workcannot be dissociated from the understanding of therelationships between structures and properties. Therefore,a particular effort should be made to find new methodsof synthesis in order to better master the mesoscopicand nanoscopic aspects of matter. At the same time, weshould not overlook any present method that might lead tonew stable or metastable materials.Besides improvement of the synthesis processes and preparationof traditional materials into different morphologiesor shapes (such as multilayers, thin layers, crystals, bulkyglasses, etc.), it is important to stress the preparation ofmaterials at the nanoscale. Thus, we consider on the onehand systems involving one or several components whosedimensions are nanometre themselves, the propertiesof the obtained systems being exploited at the micro-,milli- or centimetre scale. On the other hand, we will alsoconsider the nanometre systems whose properties areexploited at the nanometre scale and for whom the notionof materials exists at a level as yet undefined.Another domain where a great deal of expansion is occurringis hybrid organic-inorganic materials and molecularmaterials. Important areas of study include:• The elaboration of materials with new architectures• The anisotropic growth of phases at the nanoscale aswell as at the micrometre scale• Creation and management of the organization of hybridsystems, most of which are amorphous (e.g., multilayers,slab-like stacking, liquid crystals)• Preparation of networks with controlled texture andporosity (micro- and mesoporous for membranes, newcatalysts, cavities with molecular print)A better understanding of the forming mode of thesesystems should allow researchers to achieve enormous

progress in the field of biomimetics and materials. One objectivefor this field is to understand and copy the modesof mineral growth within cells and living beings in order todevelop new materials and systems. This field of researchis still very young and suffers from several drawbacks, forwhich we cannot compensate without a strong collaborationbetween solid-state chemists, biologists, and physicists.These apparently separate disciplines can complementeach other in projects concerning hybrid materialswith modulable mechanical properties, adaptive hybridmaterials (e.g., photoactivity), hybrid materials for nonlinearoptical properties and “photochemical hole burning”(PHB), electrochromic hybrid materials, ionic conductinghybrid copolymers, etc.• Molecular chemistry, because of the nature of its reactionmedia composition and kinetics, is ahead of other disciplinesin understanding the intermediate steps in chemicalreactions (regarding dynamical features of reactionmechanisms). This is particularly the case regarding theprocess of choosing starting compounds vis-à-vis theirstructure, composition, and morphology, with the purposeof orienting the reaction towards the desired compound.It is important to intensify the efforts in numerical simulationsand modelling for the prediction of both structuresand properties. Simulation, in addition to experiment andtheory, appears to be a third way to solve problems in physics.The most obvious aspect of simulation is its capacityto provide quantitative answers in complex physical and/orgeometrical situations for which the analytical tools are nolonger operational. While numerical simulations can alsobe used to conceive model designs, it only accounts forcertain aspects of the physical reality. Numerical simulationsmight lead to successful predictions of (physical) behaviours,at least qualitatively. Solid-state chemistry andmaterials science’s structures-properties relationship thatimplements micro/macroscale changes can be modelledand treated with the help of numerical simulation. Particularemphasis should be given to the following in terms ofnanostructure modelling:• Modern computational techniques of the calculation ofband structures by self-consistent methods (DFTbased),including volume, surface, interfaces, etc.• A combination of the calculation of density of states,statistical physics, and numerical methods (Monte Carlo,molecular dynamics, etc.).MATERIALS: SCIENCE AND ENGINEERING43It is important to improve the properties of new and existingmaterials through the interplay among the structure, thecomposition, the mastery of the defects, and the morphology.The purpose here is to confer new and existing materialswith specific properties in relation to certain demands,such as those imposed by the disciplines of electric, electronic,catalytic, civil or mechanical engineering as well asin relation to the production of equipment based on optical,optoelectronic, electric, or magnetic components.We need to characterize with an ever-increasing fineness thechemical, structural, and physical properties of the pure compoundsand their association within heterogeneous systems(bulk and interfaces in wide ranges of operating conditions).It will be a question of extending and deepening the understandingof the existing relationships among the chemicalcomposition, the nano- and microscale molecular structures,and their properties. This particularly concerns granularmaterials, porous media and, in a general way, thosematerials for which the surface/volume ratio is very high.One spin-off of new synthesis processes and the means inwhich materials are characterized at the nanoscale (interfaces,nanoparticles, aggregates, etc.) is the developmentof a nanochemistry and a nanophysics, which will leadnanotechnologies. The recent emergence of carbon andboron nitride nanostructures is a promising example.Finally, we must compare the respective outcomes of characterizationmethods and calculations in order to permit aqualitative and quantitative study of the chemical bond insolids (charge transfers, band structures, etc.). What arethe most appropriate methods to study the ionocovalentsolid?1.4.3. Molecular Inorganic Chemistry – New Routes toHybrid Materials (Inorganic and Inorganic-Organic)Looking toward the 21 st century, the nanosciences will be,like biology, one of the fields that will contribute to a highlevel of scientific and technological development. At thebeginning of this new era, molecular approaches of solidstate chemistry and nanochemistry have already reached ahigh level of sophistication. Today we are close to masteringthe synthesis of many organic ligands or molecules,coordination metal complexes, functional organo- or functionalmetalo-organic precursors with functional nanobuildingunits (NBUs; or NBBs for nanobuilding blocks)carrying magnetic, electrical, optical, or catalytic properties.A large amount of research has been undertaken to obtainorganic templates (surfactants, dendrimers, organogelators,polymers, block copolymers, multifunctional organic

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGARTconnectors, biopolymers, etc.) and to understand theirphysicochemical properties. Indeed, many research programmesor research actions have been devoted to OrganizedMolecular Systems (OMS) or Organized PolymericSystems (OPS).(a) State of the artNowadays, chemists can practically tailor any molecularspecies – from molecules to clusters or even to nanosizedparticles, nanolamellar compounds, or nanotubes. Clustersare mainly being used as model compounds, whilenano-objects are common in the more applied researchfields.(b) Future visions and expected breakthroughsNew molecular compounds and innovative NBBs will, ofcourse, appear in the near future. The challenges of thisnew century are related to the smart use of these highly sophisticatedchemical tools for research in biology and/ormaterials science.The nanostructure, degree of organization, and propertiesthat can be obtained for hybrid materials certainly dependon the chemical nature of their components, but they alsorely on the synergy between these components. Thus, akey point for the design of new hybrids is the tuning of thenature, extent, and accessibility of the inner interfaces.44The various characteristics of the soft chemistry-basedprocess (molecular or NBB precursors, organic or aqueoussolvents, low processing temperatures, and processingversatility of the colloidal state) allow the mixing of inorganic,organic, and bio components at the nanometric scalein virtually any ratio, leading to the so-called hybrid organic-inorganicnanocomposites. An extraordinary amount ofresearch has appeared in the field of hybrid materials, indicatingthe growing interest of chemists, physicists, andmaterials researchers to fully exploit this technical opportunityfor creating materials and devices benefiting thebest of the three realms: inorganic, organic, and biological.Because of their high versatility, which offers a wide rangeof possibilities in terms of chemical and physical propertiesand shaping, hybrid nanocomposites present the bestmeans for both facilitation of integration and device miniaturization.Moreover, hybrid materials can possibly be used directlyas innovative advanced materials or as precursors of novelinorganic solids, opening the way to promising applicationsin many fields, including optics, electronics, ionics,mechanics, membranes, functional and protective coatings,catalysis, sensors, and biology.In the United States and Japan, scientific production inmolecular inorganic chemistry is more important than it isin Europe. This is probably caused by a more empiricaland systematic approach to the research by the U.S. andJapan. However, in Europe chemists working in this researchfield have a better understanding of the mechanismsinvolved in the formation of materials and, consequently,a better control of chemical reactions and a goodreproducibility of their results. This European approach,which is based on outstanding, comprehensive fundamentalresearch in complex systems, must be encouraged.A suitable method for a better defining of inorganic componentsand hybrid interfaces exists in the use of perfectlycalibrated preformed objects (such as clusters, nanoparticles,or nanolayered compounds) that keep their integrityin the final material. The variety found in nanobuildingblocks (nature, structure, and functionality) and linksallows to build an amazing range of different architecturesand organic-inorganic interfaces associated with differentassembling strategies. The confinement of highly dispersednanobuilding blocks in hybrid or inorganic matrices, or theorganization of NBBs on textured substrates, could providelarger concentrations of active dots and better-definedsystems, and could help to avoid coalescence into largerill-defined aggregates while keeping or enhancing specificmagnetic, optical, electrochemical, chemical, and catalyticproperties into the nanostructured hybrid materials.Because there now exists a basic understanding of the roleof molecular and supramolecular interactions betweentemplate molecules and hybrid or inorganic-based networks,templated growth-based processes using organicmolecules and macromolecules as structure-directingagents can now allow the construction of complex architectures.These strategies are used by researchers, who try,somewhat naively, to mimic the growth processes occurringin biomineralization.Strategies combining the nanobuilding blocks (NBU orNBB) approach with the use of organic templates that selfassembleand allow to control the assembling step haveto be more developed. This combination between the“nanobuilding block approach” and “templated assemblingapproach” will be of paramount importance in exploringthe possibilities for building hierarchically organized materials,particularly in terms of structure and functions.In the near future, original materials will be designedthrough the synthesis of new hybrid nanosynthons (hybridons)selectively tagged with complementary connectiv-

ities, allowing the coding of hybrid assemblies presentinga spatial ordering at different length scales. Hybridons carryingchirality and/or dis-symmetry (Janus-type NBBs) andcomplementary functionalities will open new pathwaysfor the synthesis of these materials.With skilled chemists setting original pathways in materialsprocessing, numerous scientific breakthroughs can beexpected in this field. The synergy between chemistry andchemical engineering will permit an access to materialshaving complex structures that allow a high degree ofintegration. In particular, a synthesis obtained through theconstruction of materials by the simultaneous use of selfassemblingprocesses and morphosynthesis (exploitingchemical transformation in spatially restricted reactionfields) coupled with the use of external forces (such asgravity, electrical and magnetic fields, and mechanicalstress) or even through the use of strong compositional fluxvariations of reagents during synthesis (open systems) willallow the generation of innovative hierarchical structures.Chemical strategies offered by such coupled processes(self assembly + morphosynthesis + external solicitations)allow, through an intelligent and tuned coding, the developmentof a new vectorial chemistry that is able to direct theassembling of a large variety of structurally well-definednano-objects into complex architectures. Multiscale-structuredhybrids or inorganic networks (from nanometre tomillimetre) will open a land of opportunities for the designof new materials. Could these new synthesis strategiesallow us to dream of a future where it is possible to buildintelligent advanced materials that respond to externalstimuli, adapt to their environment, and self-replicate, selfrepair,or self-destroy at the end of their useful life cycle ?(c) Research needsSuch an innovative field of research will strongly benefitand become more mature through developments and advancesin the following areas:• Better knowledge of soft chemistry routes from precursorsto materials.• Improved knowledge of interfacial chemistry and physicochemistryof nanocomposites.• Study of phase diagrams of hybrid composites.• Better knowledge of organized-matter soft chemistry.• Study of order/disorder transition in hybrid nanosystems.• Relation between order and disorder and a given propertyof the hybrid (e.g., mechanical).• Better knowledge of reactivity, stability, and connectivityof NBBs.• Synthesis of new nano-objects and nanohybrids withtuned functionalities, with dissymmetric functionalitiesor carrying chirality.• Synthesis of nanoparticles with a controlled surfacechemistry, adjustable size, sharp- sized distribution, andredispersability.• Clean and environment friendly process.• Development of 2-D hybrid networks, lamellar, films, etc.• Development of bio-inspired materials.• Hybrid materials having modulable mechanicalproperties.• Development of materials that can adapt their responseto external stimuli (e.g., pH, solvent, light, external fields,temperature).• Smart functional coatings (highly hydrophobic or highlyhydrophilic, protective, anti-corrosion, anti-scratch, etc.).• Intelligent, hierarchically structured membranes thatcan couple separation and catalytic processes.• New adsorbants.• Hybrids for photonics having photochromic, emission,absorption, lasing, nonlinear optical, electroluminescentproperties for designing new sensors, optical memories,lasers, and display devices.• Development of biohybrids that will benefit fields, suchas biosensors, imaging, immunoassays, vectorizationwith controlled release, hybrids allowing better compactionand thus transport of ADN, protection of fragilebiocomponents, etc.1.4.4. Inorganic Amorphous Solids – GlassesBecause of their thermodynamic status as frozen liquids,glasses occupy a peculiar position in the general classificationof materials science. Above the so-called glass transitiontemperature, these metastable but extraordinary solidsexhibit temperature-dependent plasticity that allowsindustrially controlled operations such as blowing, fibering,and moulding. Under the same conditions, these metastablecompounds tend to come back to equilibrium innucleating microcrystals or molecules, forming vitroceramicsor foaming glasses. This situation could enhancesome properties, such as mechanical strength, but couldalso be detrimental to others, such as light propagation inoptics. The easy glass-forming ability is the privilege ofsome oxide families, such as the silicates, which allow usto prepare such sophisticated objects as optical fibres fortelecommunication and low-cost products for the automobileor building industry. From a purely marketing orpublic visibility point of view, these materials are the drivingforce of the research and glass industries.MATERIALS: SCIENCE AND ENGINEERING45

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART46Curiously, these paradoxical materials could be synthesizedat a mass-production level in large homogeneouspieces, but their structures at a nanometre scale are stillobscure. Recent programmes have liberated the exoticvitreous materials from their stereotypical research nichesthrough the development of new nonoxide glass compositionsthat offer optical properties not permitted bytraditional oxide glasses. In addition to benefiting the optoelectronicindustry by creating new materials for originalfunctions and devices, these new glasses allow a betterunderstanding of the concept of liquid polymerization andglass formation.We are in danger of being mired in Byzantine and esotericdiscussions about the nature of glass, and not gaining significantknowledge of the structure of the actual material.It must be accepted that basic research should be drivenby specific targets that lead to actual applications. Thisoffers the advantage of stimulating creativity, especiallyamong the next generation of researchers, permitting ameans for objective evaluation as well as raising the interestof the industrial community.(a) State of the artResearch on vitreous materials is by essence rather empiricaland time and labor intensive, but the investment isjustified by the unique characteristics (in terms of homogeneity,volume, shaping, and purity) of the products. Inthe last few decades, basic research in the field has beendriven by pure academic curiosity or technological need,and in both cases, with great success. The following domainshave been especially prolific:i) Glasses for photonics is the sector having the most spectacularresults. Driven by telecommunication needs, outstandingresults have been obtained in the preparation ofultrapure silica glass for fibres in such a way that the theoreticallimit in transparency has been reached in the alltelecomwindow. Also, the development of rare earth dopedglasses for optical amplification, as well as the possibilityof local modification of the glass refractive index under laserillumination, is revolutionary. The association of Bragggratings writing, optical amplification, and planar waveguideintegrated optics on glass to split and recombine theoptical signal has been proved to be the key factor in theworldwide success of Dense Wavelength Division Multiplexing(DWDM) for high-capacity information transmission.Other lanthanides than erbium are needed to expandthe all-telecom window, but their efficiency will be dependenton new glass matrices that have low phonon energy.Some preliminary positive results have already been obtainedwith exotic materials such as fluoride- and chalcogenide-basedglasses.Another important research effort has been the developmentof glasses having nonlinear properties for optical fastswitching second harmonic generation and for local masteryof the refractive index under light of electric fieldexposition. This newborn field has fascinated both theacademic and industrial community.New chalcogen-based glasses having excellent transparencyin the infrared range, particularly in the two atmosphericwindows, are in the pioneer stage of development.They will be used in the moulding of low-cost IR opticsfor cameras or night-vision systems to assist drivers, firefighters, police officers, and others operating under conditionsof poor visibility.The mastery of glass fibering is critical not only for telecommunicationsbut also for the development of opticalfibre sensors operating in the visible, but also in the infraredlight range, which will permit the in situ observationand collection of precious information on chemical andbiological processes.ii) Glass surfaces are a permanent subject of investigation.This is necessary for a better understanding of basic problemssuch as corrosion mechanisms, fractures propagation,ionic exchange for glass strengthening, and antireflectiveor reflective coatings for improving the thermalcharacteristics of window glasses. The controlled modificationof the glass surface refractive index by implantationionic exchange, and thermal or sputtering deposition hasalso received a great deal of attention for its possibilities inplanar or channel optical wave-guide development. All ofthese technologically oriented objectives need to be supportedby a strong mastery of the fundamental concepts ofchemical bonds, diffusion, relaxation, local structures andmechanical stress. In connection with the previous topicof glass photonics, the field of glass interfacing with othermaterials is also very important. Glasses are almost everywhereand can be in contact with many different compounds,ranging from metals to biological tissues. This observationhas generated creative works on bio-glasses andtheir interface with bones as well as interface mechanismsin glass/metal welding.Important but limited contributions have also been publishedon composite materials involving interfacial problemsbetween glasses and polymers that are both in thevitreous state and that raise both fundamental and technologicalinterest. The control of the glass-to-crystaltransformation has permitted the mass production ofvitroceramics, composite materials having exceptionalmechanical properties. This is a good example of industrialfertilization by basic research.

iii) The last decade has also been characterized by the discoveryof new glass-forming systems belonging to a wide-rangeof chemical families, from the chalcogenides, to the fluoridenitrides, to original metallic combinations, (e.g., Zr/Cubased). These new glasses have reached a maturity thathas justified the development of prototypical industrialproducts, but the underlying reasons for glass formationand the criteria for stability are still unknown.iv) The same period has also seen the emergence of mathematicalsimulation approaches as well as access to powerfulinstrumentation based on neutrons, X-rays, synchrotronradiation, and variable spectroscopies such asMössbauer, NMR, and Raman. This situation has permittedthe opening of a small window into glass structures,which for the most part still remain a mystery especially ata medium-range order.v) In general, glass research in Europe is characterized bya parcelling out of programmes and funding such that theresearch is always driven by short-term demands. The consequenceis that there is never enough time to reach significantprogress. On the other hand, in Japan, the policyis quite different. Through Exploratory Research for AdvancedTechnology (ERATO), long-term programmes aresupported. For instance, the HIRAO Active Glass Projecthas been launched for at least five years, allowing creativeresearch in such areas as new glass discovery and physicalproperties, and also providing a permanent structure fortransfer of research to industrial applications. In the U.S.the glass community is well identified through the glassdivision of the American Ceramic Society, which providesa permanent forum for exchange with many industries,ranging from buildings to art to telecom. This situationdoes not exist in Europe, which needs to be strongly encouragedto fertilize the cross-exchanges between basicresearch and application in the glass field. This is especiallyimportant because the field is always evolving, withsuch fast-growing markets as telecommunications.(b) Future visions and expected breakthroughsIt is now clear that glasses, when compared to other materials,offer the unrivalled advantages of easy shaping, homogeneity,and large-volume production. However, theprice paid for these superiorities is the necessity for perfectcontrol of the glass-forming conditions, a precise ratioin the glass-to-crystal balance, and mastery of all kinds ofperturbations, which usually arise at the surface. Oncethese problems are solved, new low phonon energy glassesbelonging to nonconventional families such as the halides,chalcogenides, and others will play a key role in the futureof photonics.It is critical to encourage a priori research on new chemicalcompositions instead of merely following the demandsof the technology. New materials will automatically generateinterest in the immense field of photonics and will alsogenerate new ideas for applications. The creation of newglasses, with the periodic chart as an inspiration, will assurethat this science is not merely at the service of technology.For example, in the past, glasses were not identifiedas their own EC materials research programme. Instead,they were considered to be a subprogramme oftelecom or another area. Photonics will continue to be themain partner of new glasses through the huge market oftelecom, but will also partner with glasses because of thegrowing need of optical sensors. Important breakthroughsare expected in new glasses, particularly in the design ofglass-integrated devices, including main optical functionssuch as amplification, splitting, or filtering. The understandingand control of phenomena such as photo-refractivityand electrical poling will be necessary. Obviously,new emerging fields such as bioglasses or compositeglass/polymer materials will find a significant amount ofsupport for development due to a strong industrial andmedical demand.The materials scientists cannot be proud of the results obtainedin the field of batteries and energy storage in general.Glasses have received very little attention in this domain,and they must be reconsidered as potential materialsfor cationic or anionic conductive membranes,especially when considered in their plastic regime. Futurebreakthroughs in this critical field will come from lookingat glasses as viscous liquids. Many development lines arealso expected, particularly for films in association and complexcompositions in order to obtain unwetable, self-cleaning,and unbreakable glasses.(c) Research needsThe number one priority in the frame of a long-term basicprogramme is clearly to encourage the creation of newvitreous materials. This includes the discovery of new,original glass families that correspond to the control ofsubtle interactions among a complicated ensemble of atoms,as well as the mastery of the industrial compositionsfrom a chemical and chemical-bonding point of view. Inorder to understand the deep-formation mechanism,many powerful instruments are available for structuralinvestigations, but they need to be restricted to selecttypes of novel glasses.The interactions of light with glass is also a priority andcorresponds to scientific interests as different as photorefractivity,ultra-transparency, broad band transmissionfrom deep UV to far IR, non-linearity, fluorescence, pho-MATERIALS: SCIENCE AND ENGINEERING47

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART48tochromism, optical sensors, etc... Glasses for telecom willcertainly be supported from the telecom side, but opticalglasses for sensors, lasers, and IR technology which havebeen neglected to much until now need to be encouragedto put the European industry at the same level as in theU.S.Research programmes on glass surface need also to be reinforcedfor a better understanding of mechanical, opticalproperties, interfacial problems with other materials. Thisinclude for instance anti-reflecting or hard coatings andall kinds of glasses. Also funding must be saved for exploratoryprojects corresponding to specific niches such as bioglassesor electrochemical glasses for batteries and otherexotic applications.The investigation of glass formation mechanisms from themolten salts and also through sol-gel or gaseous phasesmust be considered as long-term projects that will generatenew ideas for the access to new materials.The glass surface also needs to be the subject of specialattention because it corresponds to the place that interactswith the outside and where defects or anomalies propagateinto the bulk. A good knowledge of surface chemistrycould also help the industry control chemical or mechanochemicalpolishing.From a purely fundamental viewpoint, efforts should bepursued in the understanding of the vitreous transition andthe modelling of glass structure.1.5. Soft Materials and Polymers:The Rise and Decline of Polymer Science & Technology in EuropeP.J. Lemstra | Faculteit Scheikundige Technologie, Technische Universiteit Eindhoven;5612 AZ Eindhoven, The NetherlandsMacromolecular Sciences and Polymer Technology atCrossroads?Europe is facing a major restructuring of its polymer producingindustry with many mergers and a strong decrease in longtermcorporate research within many companies. In combinationwith a strong decrease in the enrollment of students inphysical sciences in the last decade, the future of polymer science& technology in Europe might be at stake. In this article,the situation is analysed with references to the other invitedauthors in this special Magazine of the European PolymerFederation (EPF).Europe has been the cradle for Polymer Science & Technology.At the very start of the last century, Baekeland synthesizedthe first fully synthetic material in Gent (B). PolymerScience was founded in the 1920s when Staudingerpostulated its concept of a polymer chain, consisting ofcovalently bonded monomeric units. The birth of the polymer(plastic) industry took off after World War II and wasboosted by the invention of Ziegler and Natta’s heterogeneouscatalyst systems, in the mid 1950s, enabling theproduction of (linear) polyethylenes and stereoregularpolypropylenes at relatively low pressures and temperatures.In retrospect, the invention of the Ziegler/Natta catalystsystems and the implementation by industry in direct productionis the paradigm of co-operation between academia/governmentalinstitutes with industry. In the 1950swithin 5 years, Montecatini in close co-operation with theuniversity of Milano (Natta c.s.), were able to develop acommercial process to produce ‘isotactic’ polypropylene[1]. The further development of more efficient catalystsystems (by a factor of more than 10.000!) by Montecatini,Montedison, Montell (now Basell) shows the strengthof industrial R&D, viz. optimization to the extreme. Thecurrent production of 30 million tonnes of i-PP per annumat a cost of around 0.5 Euro/kg, viz. 6 kg/capita in the world,shows the tremendous impact of the invention by Nattaand Ziegler.In the 1980s, the novel homogeneous single-site (metallocene-based)catalyst for the production of polyolefins, withenhanced control over the molecular structure, were alsorooted in academia in Europe (Kaminsky/Hamburg; Brintzinger/Konstanz).The impact on the industrial polymerproduction is not yet clear but expectations are runninghigh.

The area of synthetic polymers is usually divided into3 sectors, viz. commodity plastics, engineering plastics,and speciality polymers. At the end of the 1970s, the areaof commodity plastics was considered to be rather mature,comparable to the steel industry (a few standard gradesproduced in high volumes at low costs) whereas the futurewas foreseen in the area of speciality polymeric materialsand products. However, industry has developed numerousgrades based, e.g., on supported Ziegler/Natta catalystsand copolymerization technologies. With the developmentof the novel metallocene-based single site catalysts, in principle,even more control is gained over the moleculararchitecture and novel copolymer grades and new polymertypes could be produced, such as syndiotactic polypropylenesand polystyrenes. Consequently, the term commodityplastics is not applicable anymore. The name polyethylene,the polymer produced in the largest amount (closeto 50 million tonnes/annum), is in fact only generic andrepresents a family of numerous grades, some of whichcan be considered to be specialities.The 1980s can be considered as the decade of ‘High-Chem’in view of huge research efforts, both in industry and academia,to search for ultimate performance for polymers asconstruction materials (liquid-crystalline-polymers; highperformancefibres and light-weight composites; novelpolymer blends with synergistic properties compared withthe constituents etc.). Moreover, a new dimension wasadded to polymers: functionality. Examples are polymericmaterials that conduct electricity (Heeger, Mc Diarmidand Sirakawa, Nobel Prize for Chemistry in 2000) werediscovered and polymers that emit light (poly-LEDs) uponapplying a voltage (Friend c.s. Cambridge).Despite the major research efforts during the last twodecades, the volume of speciality (functional) polymers,engineered on a molecular scale for specific applicationsdid not increase in volume, it is still below 1 vol% despitehigh expectations. This low number seems not only to applyto the production volume but also to the production value.Nevertheless, speciality/functional polymeric materialsand products are indispensable nowadays in many applications,notably in the ICT and medical technology. Companiessuch as Philips take a serious effort to make use of specialitypolymers, for example in display technologies.In retrospect, synthetic polymers are typically materials ofthe 20 th century in terms of birth, growth and innovationsand Europe has played a key-role in these developments,often in close concert between industry and academia. Atthe turn of the century, however, drastic changes occurredwhich could have a profound and adverse effect on thefuture of Polymer Science & Technology in Europe:• In the last decade, some leading polymer producing companiesin Europe, with the prime example of Hoechst,decided that their future business is not focused anymoreon polymers (plastics) but on ‘Life-Science’. Thehighly cyclical petrochemical industry with unpredictableprofit is incompatible with the new trend of shareholders value.• Major mergers occurred, e.g. Petrofina-Elf-Total, Basell(Shell/Montell/BASF and the former Hoechst partsElenea and Targor) and BP/Amoco, a process that appearsnot be completed up to now and takes place in theU.S. as well (DOW/UCC; Exxon/Mobile).• In general, corporate research activities within the petrochemicalindustry declined, or were even terminated(Akzo Nobel) including potential promising developments,e.g., the polyketone (co)polymers, Carilon ® byShell.The driving force for the events mentioned above is costreduction which can be realized by increasing the scale ofoperations, not only in terms of the size of the newly mergedcompanies (sales) but also in terms of plant capacities.Currently, up to 600 kilotons/annum polypropylene plantsare under construction. Combined with the trend of recyclingin the automotive industry, the future focus will beon simple, cheap polymers, with a preference to use monomaterialsinstead of sophisticated blends, one of the majorresearch activities in the 1980s with thousands of patentapplications per year (may be this statement is for the momentonly applicable for blends produced in reactors andnot for sophisticated blends produced by mixing). Thestrong growth of the cheap and versatile polymer polypropylene,reinforced with fibres and/or particulate fillers, inthe past decades, penetrating in the area of engineeringplastics (automotive) demonstrates this trend.Considering the present situation, the title of this articleseems to be justified. The key question for the future iswhether the polymer manufacturing base, after consolidation,will stay in Europe or will move out of Europe in duetime, e.g., upstream to the oil wells in the Middle-East oreven more eastbound, to China .A parallel, but even more important question, is whetherthere will be a market in Europe for specific polymer gradeswith a high(er) added value than the standard bulk grades,produced by dedicated plants close to the customer (customerintimacy).The gap between the petrochemical industry, with thefocus on consolidation and a strong increase in the scale ofoperation (plants producing up to 600 kilotons/annum),vs. the world of speciality/functional polymers in variousMATERIALS: SCIENCE AND ENGINEERING49

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART50140012001000800high-tech applications, on a scale of kilograms, is apparentlywidening. Producing specific grades in large capacityplants is contradictory.The gap could be bridged, in an optimistic future scenario,by stimulating young scientists and engineers to becomemore entrepreneurial and to start small-sized companiesfor development and initially low volume production ofspeciality polymers, which eventually can be taken over bywell-established companies eagerly looking around forproven novel technologies which are not generated so easyanymore in-house due to their extensive trimming of corporate,long-term, research. The current trend of outsourcinglong-term research by industry to academia and governmentinstitutes could well catalyze this scenario. Ona national scale there have been several initiatives topromote co-operation between academia and industry, e.g.,the IRC’s in the UK, the Danish Polymer Centre andrecently the Dutch Polymer Institute (DPI) where the researchagenda is set in a strategic alliance between universitiesand industry (for more info visit: www.polymers.nl).Fig. 1.10. Enrollment of students in chemistry and chemical engineeringin the Netherlands.The question to be answered is whether in the present climateof a unifying Europe the dedicated (young) workforcecan be found and motivated to take up the challengeof scientific entrepreneurs in the area of polymeric materials.A lot of challenging jobs have been lost in the petrochemicalindustry, due to trimming of corporate researchand mergers. As a consequence (and this is the personalopinion of the author), the enrollment of students in hardphysical sciences such as chemistry and physics has decreasedto very low numbers. Fig. 1.10 shows the enrollmentof students in chemistry & chemical engineering inThe Netherlands in the last decade, from 1200 studentsin 1990 to less than 400 students in the year 2000. Similardata can be observed coming from Germany, France, Belgiumand the UK. These numbers have to be comparedwith a developing country such as India where the five majorIIT’s (Indian Institute of Technology’s) can select eachyear their 2000 new students from over 200.000 applicants.The recent move of GE corporate research to Bangalore(India), the new John Welch corporate research centre,to be followed by others (Exxon?) is an indication thatin some board rooms the conclusion has already beenmade: the future of materials sciences, including polymerscience goes eastbound ? Looking Eeast in Europe, ourcolleagues within the European Polymer Federation (EPF)tell us that despite the often eroded infrastructure, stillmotivated (young) people pursue a scientific education.Within the EPF, the national representatives of the memberstates concluded that the strong decrease in the enrollmentin physical sciences, seemingly in line with a decreasein industrial long-term research, is considered to be the majortopic of concern where action is needed. The industryhas been invited to discuss this issue and to make anaction plan, for example during the EPF meeting in Smolenice(Bratislava) in October 2000 and again during theEuropolymer Congress, July 15-20, 2001 in Eindhoven(www.europolymer.org). The future of Polymer Science &Technology in Europe is at stake.In view of all the expertise in Europe, combined with astrong tradition in polymer science, embedded in a strongscientific culture, new ways to stimulate further developmentof polymer science & technology have to be found.In a unifying Europe, national laboratories should be linkedinto a virtual institute, stimulated by the EU. Communicationis key and the new internet-journal ‘e-polymers’could function as the platform for exchange of ideas andact as a discussion platform in Europe. Education beyondtraditional disciplinary methods at European level couldstimulate research in new areas. Many more ideas areneeded to shape the future of polymer research but for thatpurpose discussion is needed among the stakeholders.60040020001988 1990 1992 1994 1996 1998 2000 2002 2004 2006No doubt that synthetic polymers will continue theirgrowth but challenging problems will be encountered duringthis century. At present, only 5% of the world oil supplyis used to make synthetic polymers. If, however, countriesin Asia etc. will continue their growth, aiming to reach thelevel of the industrialized world (and they should), the productionvolume of polymers, and consequently, the use ofoil for this purpose will grow with a factor of ten, in competitionwith oil needed for energy. Needless to say that

macromolecular sciences, including biotechnology, andpolymer technology are coming soon at crossroads to ensurea sustainable growth of synthetic materials, increasinglybased on renewable feedstock.Combining the world of biotechnology, macromolecularsciences and polymer chemistry/technology, focusing onconcrete research targets for the (near) future, might wellbe the answer to attract and motivate talented young students.Many departments already realized that by simplychanging the name from materials into biomaterials, hada very positive effect on the enrollment, also on women.Once ‘on board’ talented young students will realize thatpolymer science, the science of making and manipulatinglong chain molecules, is a highly interesting field independentwhether these molecules are of synthetic or naturalorigin. There are major challenges ahead of us to furtherexploit the intrinsic possibilities of long chain moleculesranging from the focus on ultimate performance in1-D, 2-D or 3-D(imensions), via structuring polymermolecules in devices (displays, plastic electronics) tomimicking nature in tissue engineering and other advancedbiomedical applications.May Europe take the lead in these future developments!References1. The rebirth of polypropylene: supported catalysts, E.P. Moore Jr., Hanserpublishers (1998) (ISBN 3-446-19578-4)MATERIALS: SCIENCE AND ENGINEERING511.6. Soft Materials and Polymers:Strategies for Future Areas of Basic Materials ScienceG. Wegner | Max-Planck-Institut für Polymerforschung, 55021 Mainz, Germany1.6.1. IntroductionSoft materials are characterized by weak but neverthelesslong-range interactions among the molecular or supramolecularconstituents. These interactions lead to the formationof static and frequently also dynamic structures ofhierarchical nature and physical properties which dependlargely on cooperative interactions on various length andtime scales. The industrially most relevant class of materialsin this context are synthetic polymers. Moreover, all lifeforms are built and organized of soft biogenic materials;this includes connective tissue, bone and similar materialsfrom which the skeleton or exoskeleton are formed, thestructural elements of cells (cell membrane and scaffolds),carbohydrate-based materials in plants and produced bythem (e.g. cellulose, starch). The area also includes materialson which advanced technologies are based like colloids,liquid crystals, composite materials (fibre-reinforcedplastics), and photoresist materials as they are necessary tocreate the hardware of information technology.Most of the soft materials are based on organic moleculesor macromolecules (“polymers”). It is irrelevant for theirphysical behaviour whether they are synthetic or biogenic.In the class of colloids which consists of weakly interactingnano- or microparticles in a fluid medium we find inorganicmaterials as well, but even there, interaction with organicsurfactants is frequently decisive to obtain stable ormetastable situations. Thus, surfactants are summarizedas well in the context of soft materials. The modificationof the surface of common materials and of constructionsor parts made of common materials is prerequisite to moderntechnology. The modification by, e.g., coatings servesto protect the materials against corrosion (coatings) or abrasion(tribology), it allows for deposition of information(printing technology) or distinction (advertising, coloration)and it also helps to connect parts of different quality andfunction (adhesives).1.6.2. Polymers: State of the ArtThe production, modification, and processing of polymersis most important to European industry. The worldproduction of polymers has now by far exceeded theproduction of steel (by weight) and is close to 180 milliontons in the year of 2000. Europe has a share of ca. 28

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART52percent (50 million tons) equivalent to a production valueof ca. 100 billion €.Processing of plastics as distinguished from the productionis an industry of own character and constituency.While the production of polymers is dominated worldwideand even more so in Europe by very few big players – thechemical industry – , the processing industry is characterizedby thousands of small and middle sized industries (e.g.in Germany one finds ca. 2.500 enterprises with a total ofca. 220.000 employees). About 60 percent of the productionof polymer materials is used to supply structural materialsto the market. 40 percent are produced to serve asfunctional materials.(a) Structural polymersMost of the polymers produced as structural materials(“standard plastics”) are based on polyolefines (polyethylene,polypropylene, and similar hydrocarbon polymers andcopolymers). The final application is found in the areas ofpackaging (41 %), construction of buildings (20 %), electricinsulations (9 %), automobile parts (7 %), agriculture (2 %)and miscellaneous (21 %). The application of plastics tosubstitute more conventional materials (e.g. metals, glass,ceramics in the packaging industries) or to develop newtechnologies (e.g. audio/video discs) is innovative and aconstant source of industrial evolution. We also find substitutionof more expensive “specialty” polymers by newgenerations of “commodity” polymers. This relates to theconstant improvement of the processing properties andphysical characteristics of polyolefines by the inventionand adaption of novel catalysts in the polymerization processes.The new structural variations at the level of themolecular architecture lead to a constant evolution of theproperties in application.Innovation in, e.g., the food packaging industries by availabilityof new or improved polymer based materials is essentialto the development of the distribution and storagesystems in Europe and assists in the restructuring anddevelopment of the agricultural regions. The large-scale replacementof glass by polyester-based materials (“PET”) forfluid containers in the soft-drink industry is another example.The initial problem of plastics waste disposal has beensolved in recent years by a combination of legal actions andeconomically viable collection and redistribution systems.It is necessary to mention that speciality polymers have afirm place in modern industry and have frequently thecharacter of an enabling technology. An example is the production,application, and constant evolution towards improvedperformance of epoxyresins, a class of polymerswhich serves as insulation and packaging material in theelectric/electronic industries. It is basic to modern electronicindustries.(b) Functional polymersPolymers produced as functional materials serve in a multitudeof applications as additives, processing aids, adhesives,coatings, viscosity regulators, lubricants, and manymore. They are found in cosmetics and pharmaceutics, inall kinds of semi-prepared foods, in printing inks and paints,as superabsorbers in hygienic products and in the processingof ceramics (“binders”) and concrete, as flocculants inwaste-water treatment and as adhesive in the hardware productionof electronic equipment, just to mention a few.New developments of functional polymers have had revolutionaryeffects on the industries in which they found applicationin that they provided the enabling technologicalbase to novel or improved production systems. Moreoverin many cases totally new applications became available.An example is the now widespread use of superabsorbersin personal care products, which in itself created a totallynew industry with novel product lines. The biomedical applicationof polymers needs also to be mentioned here.Polymers play an increasing role as implants, in dentistry, inthe surgery of connective tissue and arteries as well as ingeneral medical technology. It constitutes a large marketof its own right and of interdisciplinary research activities.One also needs to mention that the provision of novel functionalmaterials has also large repercussions on the machineand production line industries. A good example isthe printing machine industry. Progress in this industrydepends largely on the provision of new printing inks optimizedfor high speed printing processes – largely a “polymerproblem”. The same is true for “laser-printing technics”,the speed of which depends largely on the polymerbased printout process.1.6.3. Research TopicsA survey among the European Industries leading in polymerproduction in the years 1998/99 gave the followinghigh-priority targets for research devoted to polymers:• Emulsion polymerization: find ways to go from batch typereaction to continuos reaction; this would need the developmentof new, most probably polymeric surfactants;the stability of emulsions and dispersions needs to beimproved, the aging and film formation need to be bettercontrolled; this would have enormous impacts on thecoatings and adhesives industries:

• Enhanced efforts in the finding and evolution ofcatalysts for olefine polymerization, with emphasis onmetallocene based catalysts. Here, copolymerization,heterogeneous catalysts to be subject to fluidized bedpolymerization processes, synthesis of elastomers bymetalcatalyzed processes are key targets.• Better data on reaction kinetics and on transport phenomenain multiple systems would greatly help to improvethe large scale production of polymer materials.• The formation and processing of particulate systems(highly filled polymers, coating formulations, printinginks etc.) which includes understanding of the growthkinetics of particles and surface grafted particles wouldhelp to advance exisiting technologies significantly.• Polymers for medical applications: polymers designed toact as implants, polymer-tissue and polymer-cell interactions,aging of polymers exposed to biosystems, materialsfor artificial organs, materials in pharmaceuticaland medical technology. High-purity polymers, membranes,membrane materials for hemodialysis, polymersin medical diagnosis.• Polymers for advanced technology: polymers as storagemedia of information (audio/videodiscs); photoresistsand related materials necessary to produce advancedelectronics hardware; polymers in display technologies:alignment layers, polarizers in LCD’s, electroluminescentpolymers for OLED’s; separator membranes andion-conducting binders in power supplies (fuel cells, Liionbatteries) for portable or mobile applications.MATERIALS: SCIENCE AND ENGINEERING53• “Solvent-free” polymerization processes are desired toreduce environmental hazards and reduce the costs ofpolymer production.• Polymerization in aqueous media, water born polymersand water based coatings would also reduce environmentalhazards of present technologies.• “Reactive extrusion”, that is creating application targetedproducts in the processing step would enhance the marketsituation of the small- and middle-sized processingindustry.• A further development of analytical methods and quantitativemethods of characterization of structure and performanceof polymer materials is highly desired; among these,in situ technics of determination of the molar mass distributionhave the highest priority; equally important is thedevelopment of fast and precise methods to determinethe structure of branched, hyperbranched, and crosslinkedsystems. The analytical characterization of particulatesystems and of dispersions needs to be improved.Most of the polymer materials in present days technologiesexhibit part of their function in contact with the outsideworld, that is by their surface properties; key wordswhich need attention in research in the immediate futureare therefore:• Adhesion: understanding and improvement of the mechanismsof adhesion and failure of adhesives, preventionof adhesion by surface modification, development of“tacky” polymers (time/ temperature/ pressure-dependentadhesive processes), general studies on wetting/dewetting processes, adhesion between living systems(cells) and polymers, “bioadhesives”.• Computational techniques: The advance of theoreticalunderstanding of the behaviour of polymer materialsopens the way to relate details of the molecular structureand changes thereof to the performance in processingand application. Large scale computing using dedicatedsoftware is necessary. However, progress in thesimulation of expected behaviour based on moleculararchitecture would greatly speed up the research processin the production of polymers, thereby giving Europeanindustry a lead over its competitors. Europe is presentlyleading in computational techniques in this fieldbut its results need to be transferred to industry and – atthe same time – the methods of simulation have to beimproved with regards to the full spectrum of applicationof polymers in practice.1.6.4. Future Perspectives of Basic Research in Soft Materialsand PolymersThe properties and the application of “soft materials” (polymers,biopolymers, composites, liquid crystals, surfactants)are based on weak but long-range interactions amongthe molecular constituents. It is poorly understood howand why these interactions lead to hierarchical structuresand in most cases time-dependent physical and engineeringproperties. The controlled achievement of the architecturesis key to applications.(a) Polymer synthesisThe synthesis of commodity or engineering polymers isdominated by the impact of finding new catalysts for improvedpolymerization processes. The need to find novelprinciples of catalysis to be used in already existing largescalepolymer production facilities is unrivalled. Moreover,

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART54tailoring the molecular structure, e.g., the mass distributionof the chain length, the stereochemical microstructureand copolymer composition to enhance the processingand performance of polymers is key to further growth.The synthesis of speciality polymers is geared towardsfunctional purposes and to polymers as enabling materials.Novel polymers are key in the development of electroopticaldevices in modern communication (e.g. light emittingdiodes, displays, sensors, batteries; see Fig. 1.11) andin biomedical applications (artificial lenses, joints, skin,arteries etc.)(b) Supramolecular structuresThe properties of polymers depend on structural organisationat various length scales. The relation between molecularstructure, conditions of processing and principles ofself-organization are largely unknown or only empiricalrules do exist. Further progress in exploiting the intrinsicproperties of polymers thus depends on gaining more insightshow to control the interactions between the constituentmacromolecules and other ingredients of the polymermaterial (pigments, stabilizers, reinforcing elements)in the course of processing. Novel processing methodsneed to be developed in the case of speciality polymersadapted to the requirements of their application in micro/macroelectronics,as medical implants or in portableenergy sources (batteries, fuel cells).(c) Transport propertiesPolymers find important application in separation processesas active or passive membranes, adsorbents or chromatographicmaterials. In batteries or fuel cells they serve asionconductors and separator materials. Much need existsto improve the relevant properties by understanding howthe transport and dynamic phenomena relate to the molecularand supramolecular structures to be achieved bysynthesis and processing.1.6.5. Future Perspectives of Basic Research in OrganicMaterials Synthesis(a) Synthesis by rational designProgress in the computer-based simulation of expected behaviourof polymers in their respective application wouldgreatly speed up the process of research and developmentin industry. However, the theoretical understanding of molecularinteractions in the context of applications is in its infancy.Relevant software does either not exist or is unable toserve the purpose adequately. The same is true for the theoreticaland computational handling of catalytic processes.Better data on reaction kinetics and transport phenomenawould greatly speed up and improve the production of polymersand enhance their performance as speciality or enablingmaterials.Reactive extrusion or – more generally – reactive processingis another topic where rational approaches supported bycomputational methods would have an enormous impact.Fig. 1.11. A flexible coated polymer foil is able to transfer white lightinto blue/green laser light.(b) Structure-properties correlationsFurther development of analytical methods to characterizethe structure and performance of polymers in spaceand time domain are prerequisite to further improve thesematerials. Fast in situ techniques of determining the molarmass distribution in the polymerization and/or processingstep have high priority. Similarly, analytical techniques toallow for precise determination of the primary structure(branching, hyperbranching, crosslinking etc.) are presentlytoo imprecise and awkward to have an impact in industry.Thus, novel high-speed analytical methods need tobe found.(c) High-purity synthesis and materialsSpeciality polymers need to be adapted to the specific purposeof their application. This requires in many cases thedevelopment of new routes to synthesis and processingbecause of the required and necessary purity conditions.Examples are ubiquitous in biomedical applications (notoxic byproducts allowed) or in electronics (migration ofeven traces of byproducts will deteriorate a device).

1.7. Carbon MaterialsR. Schlögl | Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin, GermanyP. Scharff | Institut für Physik, Technische Universität Ilmenau, 98684 Thüringen, Germany1.7.1. The Chemical Complexity of CarbonElemental carbon in its chemical allotropes of graphite anddiamond occurs in a great variety of species and has beendeveloped to a large number of highly specialised applicationsas structural and functional materials. The underlyingreason for this unique manifold of species is twofold:• The co-ordination chemistry of carbon is flexible inallowing continuos mixtures of C=C and C-C bondingin one structure. This leads to an infinite possibility of3-dimensional structures and to continuous tunabilityof electronic properties from wide-gap semiconductor(diamond) to metallic (graphite).• Carbon accepts foreign elements such as hydrogen, boron,oxygen, and nitrogen both on its surfaces and withinthe structural framework. This leads to tunable mechanicalproperties from superhard (diamond, C-B-N) to ultrasoft(lubricating graphene layers). The surface functionalgroups determine the self-organization (aggregation indyestuffs, laser toners), the chemical stability (oxidativeattack in structural applications), and the reactivitytowards stoichiometric (adsorbent) and catalytic processes(synthesis of small molecules, gas mask filters).This complexity was augmented in recent years by the creationof mesoscopic composites on the basis of carbon-reinforcedcarbon materials (CFC). The manufacture of suchmaterials for structural applications in the aerospace industryinvolves careful control of all points mentioned aboveand is an example of a super-complex material synthesis.disks, high power transistors) and in the cutting tool industry(blades for metals and silicon cutting).Large objects of graphitic carbon are used in metallurgy(electrodes for furnaces), as heat shields (in space crafts,high temperature ultra-clean furnaces, fusion reactor machines)and as functional parts in motors (pistons in Ottomotors).Carbon fibres are large-scale products used as reinforcementstructures in polymers and metals. Electronic applicationsas cables, heaters and supercapacitors are underdevelopment or existing in niche applications.Carbon composites are widely used as electrodes in batteries(Li-ion types) and in electrochemical analytics.These applications draw on the ability to intercalate foreignatoms in the structure of graphite reversibly for batteriesand on the ability to completely suppress this processby producing helically wound ribbons of graphitecalled “glassy carbon” for their apparent inertness and mechanicalstability.1.7.3. Future Application PotentialsAll areas of application still require intense research andtechnological development as in none of the areas mentionedabove where carbon is unrivalled by other materials,there are specific and limiting shortcomings of the materialsproperties.MATERIALS: SCIENCE AND ENGINEERING55Carbon plays a major role in nano-sciences. Fullerenes,nanotubes, whiskers, carbon onions are typical representativesof nano-structured carbons to which all the abovementioned variables also apply in addition to the smallscale of each object.1.7.2. Current Applications of CarbonDiamond as CVC diamond, as diamond-like carbon (DLC)and as homo-epitactic diamond plays a strategic role inelectronics industry (protective layers on chips and hardIn recent years a long list of other promising applicationswas produced by proponents of the novel forms of carbon.In all these potential areas of interest carbon is, however,competing with other material solutions under development.Almost all of these application potentials are, in addition,extremely speculative and may materialise only inthe far future. A quite incomplete list of such potential applicationis given here:• Nanotubes as electrodes for flat panel displays• Nanotubes as hydrogen storage device (probably alreadyfalsified)• Nanotubes for quantum wires

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART56• Nanocarbons in quantum electronics• Endohedral fullerenes as “second periodic table”modifying the properties of all elements known• Endohedral fullerenes as diagnostic drug• Fullerenes in polymers• Fullerenes as non-linear optical materials• Fullerenes as anti-cancer drugIn such application areas carbon materials are only asystem component. Neither the system development northe basic science for the application is in a stage yet as togive specific instructions to carbon material scientists fora targeted evolution as possible with the applications mentionedin Sect. 1.7.2. In this area basic science with a widescope for property discovery is required before any seriousassessment of potentials and risks can be made.1.7.4. The Scientific CommunityCarbon science is an active field, interdisciplinary betweenphysical chemistry, inorganic and organometallic chemistryand solid state physics. In the last 35 years the field hasseen five waves of fashionable developments which haveleft wide areas of unknown material science and variationson the themes of wide gaps of fundamental understandingof carbon properties. These waves of fashion were:• Carbon as nuclear materials (high-temperature reactorand graphite-moderated reactors)• Graphite intercalation compounds as synthetic metals• CVD diamond and superhard materials• Fullerenes• NanotubesThe waves of activities have fragmented the communitiessubstantially as the available funding is fluctuating drasticallyas a consequence of high promises and little technologicalsuccesses in the short timescales of 3-5 years typicalfor funding campaigns. The application mentionedabove required decades of continuous efforts to mature tothe present standard. Despite large conference series therespective communities rarely find and work together withthe consequence of a strong lack of coherence and frequentre-inventions of known facts.In Europe, France, and Spain are the strongest nationalcarbon communities followed by British and Germangroups who are particularly strong in application-near materialscience. Worldwide, the Japanese community is byfar the largest and most active group followed by the Europeangroups and by the North Americans. The Japaneseand Spanish communities are growing and re-juvenatingwhereas most other communities are stable or shrinking.The fluctuation in active groups is very large with a tendencyof the core competence groups to move out of thearea for lack of long-term funding.1.7.5. Research Bottleneck and a BreakthroughOpportunityThe extremely flexible chemical and hence physical propertiesof elemental carbon allow for a extreme variability inapplications. Thus, in nanoscience as well as in conventionalmaterials science the present applications are by nomeans exhausting the potential of the element. In order toexploit this potential it is urgently necessary to betterunderstand the underlying chemical and partly physicalproperties.The single most important problem for all applications isas mentioned above the rudimentary understanding of formationprinciples and restructuring processes of carbon.The generation of carbon is today a highly empirical andnot very efficient procedure if specialized carbons are considered.The bulk carbons like carbon black for tyre industryor coke for metallurgical applications may be an exceptionto this but even there massive improvements in theproduction processes (superior application properties, sustainableproduction by lower energy input) seem to be possibleas consequence of a better atomistic understandingof the thermal processes. In all high-tech applications theachievement of the desired properties is so expensive inlabour, materials, and, in particular, in energy that largescaleapplications such as in car industry (for structuralapplications) or in chemistry (for catalysis) are costprohibited.Without a driver of large-scale application it isdifficult to expect that any industry alone takes on theresearch efforts required. Public funding is scarcely availableas there is little interest in carbon science at presentafter all the disappointments with the promises from thewaves of fashion.1.7.6. Chances for an European ActionEurope could take the international lead in carbon materialsscience with a programme aiming at a science-basedsynthesis strategy for functional carbons. The German-Swiss-Austrian research initiative in CVD diamond manufactureand superhard materials was an impressive forerunnerto such a project. A centre of excellence in Karlsruheon CFC materials and strong groups in diagnostics,

modelling and analysis of adventitious carbon in flamesand automotive devices (soot formation) are further ingredientsto such a network together with the traditionalcarbon groups. Essential work packages would be:• Theory of carbon formation• Elementary processes of carbon formation (graphite anddiamond)• Mesoscale physics and chemistry of primary carbonparticles (aggregation of basic structural units, diamondmicro-crystals , nanocarbons etc.)• Surface science of carbon (adsorption, restructuring,surface defects and reactivity)• Surface and aqueous chemistry of carbon (functionalgroups, aggregation processes, oxidation, reduction)• Evaluation of the C-H-O phase diagram, search fornovel phases and structures• Defect chemistry and dynamics in carbon Mechanismsof high temperature processes and annealing (graphitization,chemical erosion)• Novel precursor chemistry (polymers, mesophase)Fragmentary knowledge does exist in all these areas. Nocoherent and experimentally sound picture has beenachieved so far. Much unknown facts are bridged, however,by qualitative concepts with little experimental underpinning(see, e.g., the erroneous expectations on hydrogenstorage in nanotubes which were put forward withoutknowing the adsorption data of hydrogen on graphite as afundamental quantity for estimating maximum adsorptioncapacities). The replacement of these qualitative conceptsby quantitative models removing the traditional separationbetween diamond and graphite science which is outdatedsince the discovery of materials with a variable contentof sp 2 and sp 3 carbon groups should be a major goal ofthe network. It would be essential to bridge the gapsbetween the communities of graphite science, diamondmaterials science and nanocarbon science. If these groupscould work together and adopt their respective paradigmsto the knowledge already available, a substantial step forwardin rational synthesis and planful modification of materialproperties of carbon can be foreseen. The networkshould not aim at the generation of specific products butrather build a technology platform enabling industry forthe implementation of improvements. A wider materialsbasis would stimulate many areas of application and couldremove the myth about a “high-tech” material of carbonwhich hinders its widespread application according to itswide span of properties. Such a programme would finallyallow to better assess the long-term system potential ofnanocarbon in larger areas of technology.MATERIALS: SCIENCE AND ENGINEERING571.8. Electronic and Photonic MaterialsA.Trampert and K.H. Ploog | Paul-Drude-Institut für Festkörperelektronik, 10117 Berlin, GermanyContributor:K. Eberl (Max-Planck-Institut für Festkörperforschung,70569 Stuttgart, Germany).1.8.1. IntroductionNowadays, it is well established that the possession andcontrol of information, in its proper sense defined as newsor knowledge, is regarded to have similar importance ascrude materials like oil. To gain the desired information intime often decides about the commercial progress of anindustrial company and, more general, of the nationaleconomy, respectively.The introduction of the personal computer, and probablymost important, the generation of the worldwide operatingInternet has driven the transition of the civil communityto the so-called “information society”: any kind ofinformation is always open for everybody if it is made availablevia Internet in the World Wide Web. Thus, since thebeginning of the 90’s, the number of Internet users increasedexponentially making the Internet to an importanteconomic factor (keyword: e-commerce).The various fields of the Information Technology in ourunderstanding include the processing and transmission ofinformation, as well as their display and memory. Thosefields undergo a strong modification since their introduction.An overview about the corresponding research anddevelopment areas is presented in Fig. 1.12.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART58• create• compute• processProcessingTransmission• signal processors andamplifiers• receiver-transducerInformation TechnologyDisplay• screens• projectionsMemory• optical, electrical andmagnetic• permanent-transitory• read-writeFig. 1.12. Overview of the various fields of the Information Technologyand their present research areas.Revenue($ billion)543210The credo of modern Information Technology seems to bevery simple: making everything smaller, faster, cheaper -issues which are strongly interrelated and thus reachinginto the broad spectrum of electrical, chemical, communicationand computer industry. In the past two decades,these issues were one of the most important driving forcesfor the enormous economic growth within these industrialfields. This should be pointed up by means of the followingcurrent example: Since the announcement of highbrightnessGaN-based blue light emitting diodes (LEDs)by Nichia Corporation in 1993, a worldwide market forthese devices has developed. After six years, the markethas already grown from zero to more than $400 millions in1999. With the introduction of the blue-violet laser diodesbased on nitride materials, the development of nextgenerationoptical storage systems (e.g. DVD drives) is justrunning. The market forecast for both GaN-based optoelectronicand electronic devices is shown in Fig. 1.13.The total device market is projected to grow over $4.5 billionwithin the next 8 years!1999OptoelectronicsElectronics2001 2003 2005 2007 2009Fig. 1.13. Market forecast for GaN-based optoelectronic and electronicdevices [1].1.8.2. Present Situation – State of the ArtSince the early 70’s, device fabrication in the microelectronicsindustry, the leading branch of Information Technologyindustry, has followed Moore’s law in describing an exponentialbehavior for the reduction of the characteristic lengthscales of the devices (Fig. 1.14). This reduction in the sizeof circuit features, going ahead with higher number of operatingunits per chip, simultaneously results in an exponentialincrease of processing power and thus in higher deviceperformances. This fact is the main reason for the formidablefinancial success of the microelectronic industry.If following Moore’s law for the next decade, the minimumdevice size will approach the 100 nm-range and the minimumgate oxide thickness will shrink to a few nanometres,respectively (Fig. 1.14). However, as feature sizes in electroniccircuits move into the nanometre-size regime, fundamentalphysical limitations begin to emerge that are indicatedby the transition from classical to quantum physics.These limitations include rather obvious issues, suchas the non-deterministic behaviour of a small amount ofswitching charges, as well as basic quantum mechanics issues,like size quantization opening up significant gapsbetween energy levels and the ease of electron tunnellingthrough ultra-thin insulating barriers. Furthermore, thetechnological limits have to be overcome. For instance, astandard lithographic technology is not yet available forstructuring down to nanometre-scale sizes; and, the fundamentalproblem has to be solved that future nano-devicesshould have lower power consumption.The Semiconductor Industry Association (SIA) has developeda roadmap [2] enforcing limitations of the conventionalscaling approach. This roadmap defines the continuedimprovements in miniaturization, speed, and power

Device size100 m10 mreduction in the information processing devices: sensorsfor signal creation, logic devices for operating, storagedevices for memory, displays for the visualization, andtransmission devices for communication. As a concreteexample, the specifications for electronic devices after theyear 2010 are summarized as follows:• Feature sizes in the order of 30 nm or smaller• Over 10 8 transistors per cm 2 for logic• Over 10 10 bits per cm 2 for memory• A cost of less than 50 µcent per transistor for logic• A cost of less than 600 ncent per bit for memory• Operate at greater than 10 GHz• 1.4 billion devices must consume less than 170 WConventional deviceNatural limit ?tailored materials will become more and more importantbecause materials properties can be changed with thereduction of their dimensions and the portion of surfacesand interfaces will strongly increase compared to the volume.Thus, the interface itself will be dominant and willeven control the function of the low-dimensional heterostructure.Semiconductors like silicon and silicon carbideor the III-V compounds including the group-III nitrides,respectively, will remain the basic materials, but the synthesesof new components and the combination of verydissimilar materials under well-defined conditions withnovel functionalities will become more important.Diverse statements are emerging in these days and discussedwith respect to their potential to solve the problemsappearing with the above mentioned demands. Besides,two possible ways are distinguished, the evolution ofconventional information processing and the revolution ofinformation processing, following different visions.MATERIALS: SCIENCE AND ENGINEERING590.1 mTunneling limit1 m10 nm0.1 nmTransition regionQuantum deviceAtomic dimensionOxide thickness0.1 nm1960 1980 2000 20202040YearFig. 1.14. Device size and oxide thickness vs. time scale demonstratingMoore’s law. Critical limitations and novel research fields are indicated.Such mandatory demands can only be realized withdramatic changes in fabrication technologies, device principles,and circuit architecture that has to include thedevelopment of novel materials and material combinations.The time for science maturing into industrial technologyis approximately 10 - 15 years, this means that the time forstarting these new research topics is just now.Nanotechnology, and in particular nanoelectronics, isregarded worldwide as the key technology for the newcentury [3]. Strong advances in nanofabrication alreadyallows the realization of electronic, optical, and magneticartificial structures in atomic dimensions operating on thebasis of quantum phenomena. The giant magneto-resistanceeffect, the quantum cascade laser or the single electrontransistor should serve as only three prominent examples.In this context, the question about suitable and1.8.3. Evolution of Conventional Information ProcessingThis rather traditional route is based on the continuity ofthe conventional technologies such as the well-established“top-down” miniaturization approach combined with thinfilm technology. In the top-down approach, smaller structuresare created from larger ones with lithographic techniques.However, this way has to include a miniaturizationprocedure adjusted with new lithographic methods andmaterials systems in order to reach the nm-range.Although, the most important basic material will be silicon,because of its low price, mature sophisticated technologyand compatibility to other existing technologies,the development of new materials and combinations withsilicon will be inevitable. Fig. 1.15 presents an overviewabout the potential research areas for application of newfunctional electronic and photonic materials arranged invarious fields of Information Technology. In the following,some of the most important material problems are summarized.(a) Materials for lightingThe illumination market for incandescent and fluorescentlight bulbs amounts to more than 1.5x10 10 US$ per yearworldwide with increasing tendency. The introduction ofwhite light emitting diodes (LEDs) offers the advantage ofincreased lifetime and of economized energy. Thus, replacingall conventional bulbs by white LEDs would resultin a saving of energy equivalent to the production of 38 nuclearpower plants. However, to be successful, the internal

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART60Materials for Si-MOS(Nano) ElectronicsMaterials for Spin ElectronicsOrganic Materials for LEDs,Displays, Molecular ElectronicsMaterials for HT-Electronics,Solar Cells, Sensors, etc.Electronic & Photonic MaterialsMaterials for OpticalCommunication SystemsMaterials for LightingNanotechnologyFig. 1.15. Various application fields for electronicand photonic materials and the input ofnanotechnology.quantum efficiency of the LEDs has to be improved. Forthis purpose, basic materials problems have to be solved,primarily, the development of UV/Blue/Green LEDs and,linked with it, to find best qualified substrate materials fortheir heteroepitaxy, i.e., for the oriented growth of thinlayers with high structural quality and perfect interfaces.(b) Materials for Si-MOS electronicsThe market of Si-based semiconductors is still larger than1.5x10 11 US$ per year. Materials research and developmentin this well-established field is mainly focused onconstituent materials that comply with the scaling law inorder to reach 10 1 bits/cm 2 . However, at the same time, thepower consumption should be less than 150 W for 10 9 deviceson one chip (cf. SIA roadmap).One of the emphasized problems in Si-MOS electronics isbased on the development of high-K materials, for example,replacing the amorphous SiO 2 as gate insulators. Theoptional material must naturally be compatible to the Sitechnologyand should, therefore, combine the propertiesOptionSi 3 N 4 /nitrideTa 2 O 5Issues/Problemssmall advantage, especially with buffer layerclose to being readyneed SiO 2 buffer / no poly-crystalline gatevery early stagesTiO 2 need SiO 2 buffer / no poly-crystalline gatevery early stages(Ba, Sr)TiO 3 deep states / buffer layer /no poly-crystalline gateearly stages FET (large DRAM interest)Table 1.3. Gate materials for Si-MOS electronics with issuesand problems.of high thermal and chemical stability with a perfect wettingbehaviour to the Si surfaces. Potential candidates arelisted in Table 1.3 that additionally includes current issuesand problems.MagneticEngineering (spin)Ultra sensitivemagnetic sensorSpin coherenceelementsElectron, spin, opticintegrated circuitSpinSpin dependent transportGiant magnetoresistance (GMR)Tunnel magnetoresistance (TMR)OpticsSemiconductorEngineering (charge)Non-volatile memoryMRAMTransportQuantum computingFig. 1.16. General concept for spin-electronics, after ref. [5].(c) SpinelectronicsThe concept of spin-electronics is summarized in Fig. 1.16,where the combinations of magnetic and semiconductingtechnologies are displayed. Both, the spin and the chargeof electrons contribute to new functional devices and willprobably break the limitation of existing device concepts.Specific material aspects are still at the beginning, as it isreflected by the introduction of many diverse material combinationsand concepts for the realization of magnet-semiconductorhybrid structures (e.g., ref. [4]).In general, the large potential of spintronics can convenientlybe recognized by the giant magneto-resistance(GMR) effect that only needed 10 years from discovery toimplementation in commercial devices. Further feasibleapplications are given in the figure.

(d) Materials for optical communication systemsBeside the high operating frequency of the electronic integratedcircuits, the band width, i.e., the amount of informationtransmittable over a single fibre strand, is a key factorfor the total transfer rate that can optimally be reached.This band width double every 9 to 12 month that is twicethe innovation of Si-MOS technology, consequently requiringan enormous spectrum of technical innovations(see overview in Fig. 1.17).New materials for laser diodes and novel concepts for laserfabrication are necessary in order to be able to extendthe wave length range. For instance, the artificial and thermodynamicallyunstable quaternary (In,Ga)(As,N)-system is investigated as basic material for the generationof lasers emitting at 1.5 µm wavelength [6].Nevertheless, essential material-related questions generallyremain concerning the improvement of the process control,the stability and purity of the soft films and composites,non-ideal metal/organic contact, and about the reductionof the power consumption. For example, if we take intoconsideration that the energy difference between highestand lowest occupied molecular orbital is typically 1 eV andthat the contact resistance is assumed to be about 100 ,the power consumption of a single electronic device wouldthen be 0.01W. Realizing an integrated circuit with 10 10devices (typically for CMOS device) would result in 10 8 W(i.e., a nuclear power station to run it!). This result is independentof the circuit architecture used. Most of theexperimental measured resistances are in the range of Mto G, therefore, a substantial improvement or differentthinking in Integrated Circuit-architecture is required.MATERIALS: SCIENCE AND ENGINEERING61The idea of novel all-optical devices, i.e. switches, modulators,filters and interconnects, seems to be possible withso-called photonic-bandgap materials: materials patternedwith a periodicity in the dielectric constant, which generatesa range of “forbidden” frequencies, called photonicbandgap. Photons with energies within this bandgap cannotpropagate through the material. This will allow to controland manipulate the propagation of light even withincompact systems of very small dimensions.(f) NanotechnologyAn alternative process is the use of nanostructures for electronicapplications. Nanoelectronic devices might be implementedin a circuitry by “bottom-up” approaches whilemaintaining the conventional circuit architecture (Booleanalgebra). In general, the bottom-up approach is realizedas follows: small structural blocks are built from atoms,molecules, or from single device level upward. The methodprincipally allows the precise positioning of the buildingblocks and hence their functionality. The essentiallyMaterials for OpticalCommunication SystemsLaser Diodes• extend wavelength range• increase modulation frequency• realize new conceptsPhotonic devices & circuits• non-linear inorganic & organicmaterials• optical switches, modulators, fibres ,interconnects• microelectromechanical systems(MEMS -> NEMS)Photonic nanostructures• photonic-bandgap (PBG) materials• single photon sources• holographic storageFig. 1.17. Overview of research areas for materials for optical communication systems.(e) Organic materials for LEDs, displays, electronics, etc.The vision of unlimited engineering flexibility through directcontrol of molecular orbitals combined with low-costfabrication techniques has been made organic materialsvery attractive. Organic light emitting devices for large areaprojectors or the imprint technology for “paper-like displays”are going to be successful in commercial fabrication [7].high integration level is achieved with self-assembled orself-organized functions – the most critical key issues for asuccessful transfer to industrial products (like for instancein single electron transistors). Proposed solid state deviceimplementation at this level has therefore to solve the followingessential problems:(1) controlling the critical dimension (tunnel barrier heightor the quantum dot size),

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART62NanofabricationBio-TechnologyNano-ElectronicsAdvanced Functional Materialsand Architecture ConceptsAppropriate Characterization Methods & ModellingChemical EngineeringInformation TheoryFig. 1.18. Combination of innovative research areas as the driving forcefor developing new materials in the Information Technology(2) the reduced operating temperature, and(3) the interconnection and the alignment of the nanostructures.Ultimately, a conceivable scenario to avoid the problems(1) and (2) is to build ultra-dense and low-power nanoelectroniccircuits made from purely nanometre-scaleswitches and wires. Specific individual molecules are ableto act as wires and switching devices (“molecular electronics”)combining the primary advantage that these moleculesare natural nanometre-scale structures which can beproduced absolutely identical and in vast quantities by syntheticorganic chemistry. The electronic properties are,however, still almost unknown. Again, the problem of heatdissipation is still unsolved as already mentioned in theprevious section about (e). Materials understanding andmaterials processing are thus basically necessary for a furthersuccessful development of this molecular electronics.Alternatively, bio-molecules are introduced in nanoscaledevices: DNA templates act as programmable scaffoldingupon which the electronic components can precisely selfassembled.The transfer of information along the DNAseems to be possible without the problem of significantelectrical resistance (intra-molecular electronics), butmany issues are unsolved.(g) Nano-fabrication and characterizationPrerequisite for nanoelectronics is the development ofnanoscale measurement tools, standards, and fabricationmethods. Tools for visualization and characterization arevital for understanding nanoscience in its variety and forunderstanding the nature of nano-manufacturing processes,too. Those smart nanoprobe techniques have to be accuratelysensitive to electronic, magnetic, structural,chemical or biological properties as well as the specificcombined functionalities. The techniques of microscopyand nanoanalysis based upon electrons, ions, photons andscanning probes are key assets.Nanoprobe techniques for manufacturing prototypes(atom-by-atom manipulation in the STM) are already usedon a laboratory level containing single nano-device structuresfor investigating and testing their functionality.1.8.4. Revolution of information processingThis route is more innovative and revolutionary becauseit does not rely on conventional research principles. Inaddition, it assumes pro-active strategies with long-termvisions for the knowledge-driven innovative materialsresearch.In the Information Technology arena, nanodevices willboth enable and require fundamentally new informationprocessing architectures that are radically different topresent existing. Feasible examples are quantum computing,or to DNA like data processing systems. This approachimplies that the information processing principles basedon general information theory should be more inspired bynatural biological than artificial physical systems (non-Boolean algebra). However, before being able to integratethose basic systems in a novel information technology, theyhave first to be understood in more detail, i.e., their physical,chemical, and biological structures and processes.In a second step, advanced materials and, in particular,heterosystems based on materials with very dissimilarproperties are then necessary in order to combine biologicand microelectronic information processing principles(“bio-electronics”). Here, a new kind of materials engineeringfor interface creation and manipulation must be

developed as well as novel concepts in the packaging technology(e.g., for the device resistance against outside).While device and circuit concepts are highly speculativein this area, the combination of innovative ideas from nanotechnology,nanoelectronics, biotechnology, and informationtheory together with appropriate characterization toolsand theoretical modelling will offer promising ways for realizingrevolutionary technologies in the future. This kindof advanced materials research is therefore a strongly interdisciplinaryfield, as illustrated in Fig. 1.18.1.2.3.4.5.6.7.ReferencesCompound Semiconductor, Issue July (2000) 15.Semiconductor Industry Association (SIA), International TechnologyRoadmap for Semiconductors 1998 Update.National Nanotechnology Initiative, National Science and TechnologyCouncil, Committee on Technology, July 2000.H. Ohno, Toward Functional Spintronics, Science 291 (2001) 840.T. Miyazaki, Development of the study of tunnel magnetoresistanceeffect, FED Journal 11 Supplement (2000) 40.M. Kondow et al., GaInNAs: A Novel Material for Long-wavelengthSemiconductor Lasers, IEEE Journal of Selected Topics in Quantum Electronics3 (1997) 719.B. Goss Levi, New Printing Technologies Raise Hopes for Cheap PlasticElectronics, Physics Today February (2001) 20.MATERIALS: SCIENCE AND ENGINEERING1.9. Nanotechnology and Semiconducting Materials63M. Lannoo | ISEM, Maison des Technologies, 83000 Toulon, FranceThis contribution is centred on two strongly connectedfields. We first discuss the major trends in nanotechnologyand stress its importance in a wide variety of applications.We then examine what can be a possible evolution in basicresearch on semiconducting materials.1.9.1. Some Aspects of Nanotechnology(a) IntroductionOne of the main motivations for working at the nanoscalecomes from the evolution of microelectronics towards miniaturization.This is contained in the famous empiricalMoore’s law which states that the number of transistorsper chip doubles every 18 months (Fig. 1.19)Such an exponential increase serves as a guideline for theroadmap of silicon-based microelectronics. The ultimategoal is to reach 10 11 bits/cm 2 instead of the 10 7 -10 8 realizedat the present time. However this reduction in size inducesnew effects, e.g., errors due to charge offsets, quantumconfinement effects, etc., which already manifest themselvesin the smallest laboratory transistors with a gatelength of 20-30 nm. At the industrial level the normal attitudeis to follow the roadmap and try to solve the technicalproblems associated with each generation of devices.There is consensus that this trend must end up in 2012with a minimum feature size of 35 nm.It is thus necessary to prepare new solutions if one wantsto pursue this trend further. One approach is to start fromthe ultimate limit, i.e. the atomic level, and design newmaterials and components which will replace the MOSbased technology. This is exactly the essence of nanotechnology,i.e. the ability to work at the molecular level, atomby atom, to create larger structures with fundamentallynew molecular organization. This should lead to novel materialswith improved physical, chemical, and biologicalproperties and, in turn, to exploit theses properties in newdevices. Such a goal would have been thought out of reach15 years ago but the advent of new tools and new fabricationmethods have boosted the field.Memory in bits/chip (DRAM/FLASH)0,011800M10 10350M150M10 90,164M10 828M12M Transistor per chip10 710 11 1990 1990 2000 2005 2010 2015YEARS of first DRAM shipmentMinimum Feature Size (m)Fig. 1.19. An example of Moore’s law.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART64(b) Some elements for the futureWe only consider some aspects of the tremendous developmentexpected in the field of nanotechnology.Our central point will be nanoelectronics. As discussedbefore the estimated end of the roadmap is in about tenyears where problems relate both to the cost of fabricationand to the reduction in dimensions will occur. Thereare various ways to increase the integration. One of themis to perform 3D integration. There are already start-upcompanies in the U.S. working on such projects. In thefuture one might consider that self organization techniquescould achieve this successfully. Of course therewill be problems related to power dissipation and to connectionsin such systems. The last problem will also occurfor 2D arrays of nanostructures and numerous studiesconcerning the realization of conducting wires have alreadystarted and should be intensified. Simultaneously,studies concerning new devices will be pursued. It seemsto us that silicon will still remain the central material atthe nanometre scale. Much effort should be spent on therealization of silicon based nanodevices. The physics ofinnovative device concepts and new approaches to nanostructuressynthesis are essential to such development.Improved predictive simulation techniques and characterizationmethods will also be of central importance tothe design of such new devices. This means that exploratoryresearch is necessary on subjects like quantum sizeeffects, tunnelling, exchange coupling, conductivity ofnanowires, magnetic and ferroelectric properties at thenanoscale. Due to these new physical effects, the existenceof quantum fluctuations and the importance ofpoint defects new fault tolerant architectures will be neededand must be an active field of research in the near future.The operation at room temperature and the possibilityof low cost integration into working systems are basicconstraints for the applicability of such new devices.Another rapidly emerging field is molecular electronics.The most classical aspect concerns light emitting diodesfor flat panel displays, already at the industrial stage. Oneshould note the first realizations of organic transistorswith comparable performance to amorphous silicon. Thisallows the hope of an “all organic” solution to flat paneldisplays. Another source of application already in developmentis “plastic transistors”. However, the field whichis closest to nanotechnology is electronics at the scale ofthe molecule. Here the ultimate goal is again 3D integrationwith 10 16 bit/cm 3 i.e. 10 13 logic gates/cm 2 . There arealready many studies but no clear cut demonstrations ofelectronic devices based on a single molecule yet. Amongthe numerous problems to be solved the following:• Realization of molecular devices: diode, conductivity ofa molecular wire, wiring and connections to electrodes.• Self organization for 3D integration.• Molecular circuit architecture (again fault tolerant).• Connections and thermal dissipation.• Use of DNA for the resolution of some algorithmicproblems.To the same field of research belong the rapidly expandingstudies concerning the single-wall nanotubes (Fig. 1.20),the fullerenes, and other aromatic molecules which cangive rise to molecular crystals with various optimized physicalproperties like superconductivity. This will certainlylead to new developments.Fig. 1.20. Single-wall carbon nanotube.To end up this list we must mention opto-nanoelectronicswith the optical study of individual quantum dots and theiruse in optoelectronic devices. Another trend is the fabricationof photonic bandgap superlattices to guide andswitch optical signals with nearly 100% transmission, invery compact architecture. With this in mind a remainingchallenge is opto-electronic silicon. There have beenhopes and disappointments concerning the possibilitiesof realizing silicon-based lasers. However, quite recently,optical gain in silicon nanocrystals has been demonstrated.The field of magnetic nanostructures is also rapidlyexpanding particularly due to the realization of devicesexhibiting giant magnetoresistance. There is still basicphysics to be done as well as improvements in magneticstorage. A similar situation is also emerging for ferroelectricmemories (Feram’s) where fabrication, characterization,and optimization studies are required. Anotherinteresting problem is the behaviour of nanosized grainsof ferroelectric materials.Beyond applications to electronics and computing nanotechnologywill, no doubt, lead to revolutions in the following:improved properties of materials for a variety ofuses, medicine and health with new drug delivery systemsfor instance, environment and energy with integrated sensorsallowing corrective action, biotechnology and agriculture,etc.

As a final point in this list let us mention the parallelprogress made in the context of micromechanical (MEMS)and micro-optomechanical (MOEMS) systems whichhave benefitted from the techniques of fabrication of microelectronics.These have for instance allowed the realizationat the microscale of actuators, motors, mirrors, laboratorieson a chip, etc. In view of what happens in livingworld (molecular motors) one can also expect reduction ofsize in this area. Together with progress in nanoelectronics,nanocomputing, integrated nanosensors this couldlead to the advent of what might be called nanoroboticswith enormous applications especially in health care.(c) ConclusionAs mentioned in several papers nanotechnology is likely tobe one of the leading fields of research and developmentin the next century. It will have a variety of applications inpractically all domains. It must involve different disciplineslike electronics, physics, chemistry, biology, etc. It shouldlead to the opening of new possibilities like quantum computing,optical computers, nanorobotics, with impact innearly all economic fields.The expansion of semiconductors is not limited to thatunique aspect. In the past audio and microwave applicationshave been stimulated by military needs. Now theinterest has shifted to commercial mass markets: cellularphones, size reduction of devices, improvement in transmissionquality and efficiency, increase in power and distance,etc. In these fields compound materials are increasinglyimportant (e.g. GaAs, InP, GaN, SiC). In optoelectronicsthe compound semiconductors are used to obtainlaser diodes for nonlinear optics. They play an essentialrole for fast modulation of light. In all cases, one also has atendency towards decreasing size with growing importanceof quantum phenomena.The limits of the field are not clear cut. First of all progressis not confined to applications but can also allow importantdiscoveries in basic physics, like the quantum Halleffect. On the other hand devices of the future will beincreasingly based on coupling between semiconductorsand other types of materials: normal or superconductingmetals, magnetic materials, various dielectrics, molecules,biological systems, etc. Control of the corresponding interfacesis essential. This implies interdisciplinarity involvingcooperation between chemists, biologists and specialistsin microelectronics and computer science.MATERIALS: SCIENCE AND ENGINEERING651.9.2. Semiconducting MaterialsThe increasing importance of semiconductors is due tothe fact that they have been and still are the basic materialsfor the technological revolutions of electronics over thelast forty years. Electronics represents the most importantmarket at the present time and the one that benefits fromthe fastest growth. It covers a wide range of industrialfields: computers, telecommunication, automobile, variousmass products, military and space applications, etc.In this global market, the part of semiconductors is in theorder of 10 %. The basic material is silicon, the relativepart of compound semiconductors increasing steadily.(a) General considerationsThe dominant field of application is microelectronics(mostly based on silicon) but others like audio and microwavesas well as optoelectronics are increasing at a rapidpace. Technologies inherited from microelectronics havealso allowed the emergence of new fields: microsystemsand micromechanics coupling sensors, micromotors, actuators,and microelectronics. As discussed before an essentialfeature of microelectronics is the tendency towardsincreased integration which obeys Moore’s law.(b) SubfieldsWe list here a number of key subfields (areas of long termresearch are marked by the sign*)i) Silicon based integrated circuits Elaboration and characterizationof very thin dielectrics (< 5 nm) for gate control– new types of dielectrics – very thin junctions (< 10nm) – interconnects (electromigration) – reliability of fewelectron memories and difficulties related to quantumfluctuations * – strain induced problems – growth, plasmaor chemical etching of films – progress in lithographic techniques– the possibility of optical interconnects * – optoelectronicsilicon *.ii) Large gap materials These materials have a major interestfor optoelectronics. Some of them like Zn Se, diamond,SiC despite an indirect gap, the nitrides GaN, InN, AlNallow to cover a broad spectral band. Another field of applicationis microelectronics in hostile environment andpower electronics. The difficulties to overcome are typicalfor materials studies: growth techniques appropriate to areduction of native defects – choice of substrate – controlof dopants – use in microwave and optoelectronic devices.Heterostructures and superlattices: These systems lead toapplications in microwaves, optics (in particular nonlinearoptics) and to optoelectronics. The focus will be on a bettercontrol of the layers, in particular for strained layerswhere the creation of dislocations must be avoided (forinstance via metamorphic growth). III - V compounds,

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART66of strategic importance, are among the best candidates toreach ultimate performances in microwaves. On the otherhand it is necessary to pursue studies on Si Ge in order toimprove the already remarkable results obtained with thiscompound. With regards to optics, further work is neededon optical microcavities, semiconducting or dielectricBragg reflectors as well as photonic band gap materials.iii) Nanoelectronics and nanophysics This represents longterm research on the elaboration and characterization ofbasic materials for tomorrow’s electronics. It is essential topursue studies on the following subjects (non exhaustivelist): – single electron devices memories, transistors * –lithography at the nanometric scale: X-rays, electrons,STM – near field spectroscopies applied to the characterizationand fabrication of nanosystems * – deposition ofself-organized layers on semiconductors: grafted molecularlayers, elaboration of wires, quantum dots and superlatticesof 3D crystallites: eventually application to optoelectronicsilicon * – coupling of semiconductors with organicmolecules with a given functionality or withbiological molecules * – interfaces between semiconductorsand dielectrics, superconductors or magnetic materials; application to new devices (e.g spin transistors)* –mechanical switch or memory of atomic or molecular size* – use of the remarkable properties of fullerenes, nanotubesand other forms of carbon * – development of newappropriate (fault tolerant) circuit architectures* – quantumcomputing *.iv) Non electronic micro- and nano-devices This is arapidly expanding field with micro-electro-mechanicalsystems (MEMS) or even micro-opto-electromechanicalsystems (MOEMS) (pressure sensors, accelerometers,micromotors), microfluidic devices (e.g. micropumps,microvalves), chemical or biochemical sensors as well asoptical microdevices. These realizations have benefitedfrom the technologies derived from microelectronics. Hereagain, aspects related to thin layers of semiconductors areessential. The future lies in the design and realization ofnew types of devices, of so called smart systems, in thesearch of specific applications. In a more distant futureone can foresee an evolution towards a reduction indimensions, eventually down to the nanometric scale*.The association with nanoelectronic systems might leadto micro and nanorobotics *.well as infrared optoelectronics. In all cases coupled physico-chemicalstudies are needed in order to optimize thematerials with respect to the desired properties. Anotheraspect concerns semiconducting polymers which haverecently exhibited potentialities for electroluminescenceand the realization of so called plastic transistors.vi) Theory and simulation The field of microelectronicdevices has benefitted for some time from the use of simulationand modelling techniques. These are mostly basedon the resolution of macroscopic equations incorporatinga simplified representation of the material in terms ofparameters (effective mass, diffusion coefficients, etc.)which are often fitted to experiment. Progress in computingtechniques will make these approaches more and morerealistic, microscopic processes (e.g., diffusion barriers)and electronic states being better described. Numericalcodes will be incorporated in the description of the behaviourof real devices. Efforts will be needed to describethe different steps in the realization of devices: growth,implantation, and lithography.Finally the reduction in size towards nanometric scalestogether with the ever increasing computational power beginto allow direct application of ab-initio quantum calculationsto realistic systems. Much work obviously remainsto be done in this field which must lead to the possibilityof engineering a priori the physical properties of elementarycomponents.v) Unconventional semiconductors Some new semiconductingmaterials synthesized in chemical laboratoriesmight present extremely interesting properties. This wasthe case for instance of skutteridites for thermoelectricity.Another example is provided by tin or antimony chalcogenideswhich are potentially useful for microbatteries as

ConclusionsIn this chapter the need for basic research for the differentcategories of materials has been discussed. The categoriescover metals and metallic alloys, ceramics and other nonmetallic,inorganic materials, polymers, organic materials,carbon materials, and electronic materials. Even withinthe traditional categories of materials there is plenty of researchto be done into new and poorly understood phenomena.In particular, connections need to be madebetween the chemistry, microstructure, and properties ofmaterials in all classes.A detailed analysis of the different groups reveals that thereare four important areas of research common to each: (1)the science of processing, (2) the science of characterisation,(3) measurement of properties and (4) theoreticalmodelling of properties based on the microstructure.These four aspects have to be dealt with on different lengthscales. Fundamental aspects of materials based on quantumchemistry and physics needs to be connected to microstructuralunits and large-scale structures by multiscaleapproaches. Until recently, processing of materialswas performed predominantly on a mesoscale level (in themicrometre range), but growing interest in nanomaterialsmeans that we will soon be able to design materials fromthe atomic and molecular levels.Nanotechnology is an important topic for all classes of materials.One aspect of nanotechnology is the processing ofmaterials composed of nanoparticles (nanopowders)where net-shaped materials can be formed. However, thisis only possible if grain growth can be avoided or drasticallyreduced both during processing and when in use. Theother aspect of nanotechnology is to build new nano-sizedcomponents. These components are important wherespeed is a critical factor for, e.g., nanoswitches, nanoelectronics.Experiments have been performed to determinethe properties of materials consisting of small numbers ofatoms or arrays of atoms, e.g., nanowires. An enormousamount of work still needs to be done, however, beforenanotechnology can achieve its potential.For the EU to generate and benefit from new breakthroughsin materials science, room needs to be made forfundamental, “blue skies” research in all categories of materials.The many sources of inspiration, imagination, andinnovation in the European science community need tobe supported by such forward-thinking policies if Europeis to remain one step ahead of other regions investingheavily in materials research.MATERIALS: SCIENCE AND ENGINEERING67The tasks awaiting us in the future are manifold. On onehand it is important to continue to improve existing materials(such as steels) by controlling the microstructureand/or composition (microalloying). On the other hand,research into novel materials still has great potential simplybecause of the large number of elements in the periodictable. So far only two- and three-component systemshave been systematically investigated to any significantdegree. New compounds and materials with extraordinarystructural or functional properties can be discovered byexperimenting with a wider range of elements and additives.These studies should be guided by well-groundedtheory and computer simulation to make the most efficientuse of time and resources. However, it is difficult to predictthe behaviour of materials with complex microstructures,so further breakthroughs in the area of modelling(see Chapter 4) are needed.

CHAPTER 22. MATERIALS: SCIENCEAND APPLICATION6869In this chapter materials are discussed in terms ofspecific applications for different technologies.One of the most important and challenging areas for manmadematerials is in biology and medicine. Biomaterialscan be thought of as covering two separate but relatedareas: replacement of human organs and body parts, and“biomimetics”, where we seek to synthesize materials byimitating processes and structures found in nature.Biomaterials currently used in human implants were notdeveloped specifically for this purpose, but have beenselected from pre-existing materials. This has meant thatinteractions between the implant material and naturaltissue have not yet been thoroughly examined. Ways ofimproving this situation are described in several sectionsof this chapter.In biomimetics there are different approaches to understandingthe function of structural hierarchies in biologicalsystems. Both the “bottom-up” approach and the “topdown”approach can provide interesting insights intoNature’s way of producing lightweight, tough materials inthe most efficient manner.The science of catalysis is also a very important areadescribed in this chapter. So far knowledge of catalysis(heterogeneous as well as homogeneous catalysis) has beengained mostly by empirical methods. Unfortunately, thereare barriers to the flow of information in catalysis researchdue to the substantial economic interests involved.IntroductionOptical and optoelectronic materials are of increasing importancesince optical communication is widely regardedas the future of information technology. The materialsbeing developed range from amorphous materials (glasses)to semiconducting and organic compounds. The magneticand superconducting properties of various materialsare used in a number of essential applications, and thiswork was strongly supported under the 5 th Framework Programme.A great challenge will be developing materials foruse in nuclear fusion reactors. This includes structuralmaterials for the reactor superstructure as well as plasmawall materials stable at extremely high temperatures.Materials used in the transport industry are developed bya number of different research communities. The mainaim is to create lighter, stronger and cheaper materials foruse in mass transportation systems (ships, aircraft, cars,trains). Reliability is a critical issue.The study of materials in Space is another new field thatmay generate a better understanding of processing andmicrostructure than could otherwise be achieved bydoing the same experiments on Earth. Interesting resultscan be expected.Successfully developing materials for specific applicationsrequires close interaction between scientists andengineers both in academia and industry. Many of theexamples described in this chapter show that Europe hasthe imagination, ability and experience to achieve this.▲Domain structure in ferroelectric BaTiO 3 (transmission optical micrographobtained with polarized illumination, U.Täffner, MPI für MetallforschungStuttgart).

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART702.1. Biomaterials: EvolutionN. Nakabayashi and Y. Iwasaki | Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University,Kanda, Tokyo 101-0061, Japan2.1.1. IntroductionThere is a big demand for biomaterials to assist or replaceorgan functions and to improve patients’ quality of life.Materials options include metals, ceramics and polymers.Unfortunately, conventional materials are used that werenot specifically developed for biological applications.Interaction between biomaterials and natural tissues is animportant subject for biomaterial science (see Fig. 2.1).Such information is essential to aid the design of new biocompatiblebiomaterials.Non-thrombogenic artificial surfaces are an essential targetfor synthesis. There have been many proposals to provideblood-compatible surfaces. Immobilization of heparinand urokinase, and introduction of poly(ethylene oxide)chains on the surface are promising but they do not havegenerality. Accumulation of plasma proteins on the bloodcontactingsurfaces must be minimized. Preparation ofmulti-functional biomaterials, such as non-thrombogenicelastomers and permeable membranes, is a future challenge.2.1.2. State of the Art [Metallic, Ceramic and PolymericBiomaterials]Biomaterials are widely used in medical and dental treatmentsbut their effectiveness is questionable. Almost allwere developed for general use. Some alloys and hydroxyapatiteswere introduced in orthopaedic and dental fieldsand satisfactory results were obtained. Hydroxyapatite hasthe advantage that it connects to natural hydroxyapatite inbone (see Fig. 2.1). Toxicity must be avoided but inertnessis not a high priority in biomaterials. Unfortunately, metallicand ceramic biomaterials are not suitable to replace softtissues because of markedly different mechanical properties.Conventional polymers are used for many of today’sdisposable medical devices but new functional biomaterialsare awaited.2.1.4. Future Research Needs & PrioritiesArtificial organs must be connected to our bodies duringuse but methods of connection still need to be researched(see Fig. 2.1). Infection at the interface is an unsolvedproblem in medical devices and artificial organs. Encapsulationaround implanted biomaterials is a remainingproblem, which is essential for implantable bio-sensors.Other problems in artificial organs are how to join each artificialblood vessel with the patient’s natural vessels. It isnot yet possible to get durable bonds between artificialorgans and human tissue. Biocompatible blood access isalso required for dialysis patients.Good scaffold is needed for cells and tissues other thangelatine and collagen. A three-dimensional bio-matrix isimportant for tissue engineering, especially to make hybridizedartificial organs such as artificial liver support system.2.1.3. Future Visions: Evolutionary and Revolutionary;BreakthroughsReplacing natural organs with artificial ones causes difficultieswhen they do not function properly. However, artificialorgans are necessary to support part or all of their essentialfunctions thereby improving quality of life. Artificialkidneys are one example. At present artificial heartsare only used temporarily to keep patient alive prior to organtransplantation. Availability of transplantable organs isstrictly limited. New functional biomaterials are neededto improve artificial organs.2.1.5. Highlighting Internal Research Programme NeedsHard dental tissues do not have effective wound-healingcharacteristics and do not regenerate; this was not initiallyrealized by dental researchers and clinicians. Cliniciansbelieve they could provide durable prostheses to fix defectsbut the cut tissue did not heal and suffered invasionby micro-organisms. This is termed ‘secondary caries’.More importantly, even today, it is not possible to connectartificial materials to natural tissues (including tooth substrates).It has been argued that adhesive technologyshould provide the option of better dental treatments.

TissueBiomaterialsHow to connect ?Not regenerate:ToothBiomaterialsIntimate attachment? Chemical reaction?ToothBiomaterialsRegenerate:BoneBiomaterialsas the polymer surfaces could accumulate phospholipidswhen in contact with body fluids. 2-Methacryloyloxyethylphosphorylcholine (MPC) has been prepared and thecharacteristics of copolymers were evaluated. Such copolymersare non-thrombogenic, highly hydrophilic,permeable, translucent and do not accumulate bio-activeproteins on the surface. Bio-compatibility of several artificialsurfaces could be improved by coating. There are nowseveral promising multifunctional biomaterials available,which are being applied to new types of artificial organsand advanced medical devices. This technology could openup revolutionary new fields in biomaterials research. MPCand the copolymers are commercially available from NOFCo., Yebisu, Tokyo 150-6019, Japan.MATERIALS: SCIENCE AND APPLICATION71BloodSoft tissueBiomaterialBiomaterials(Encapsulation?)Fig. 2.1. Interaction between biomaterials and natural tissue.Initially, loss of tissue needs to be minimized during thetreatment. Nakabayashi has developed new technologieswhich give tooth substrates pseudo-wound-healing characteristics;these could revolutionize dental treatments (-see Fig. 2.1). Hybridized dentine and enamel are createdon the subsurface of tissues by impregnation of monomerresins, followed by in situ polymerization. It is expectedthat hybridized dental tissue, together with impermeableand acid resistant artificial enamel, could resolve manycurrent problems in dentistry. Education in dental schoolsmust be changed to introduce this new technology widelyinto dentistry. Dental biomaterials may then eliminatemany defects in dental hard tissue and rejuvenate theirfunction.Non-thrombogenic biomaterials are widely used in thedevelopment of artificial hearts but there are difficulties intheir preparation. Artificial hearts are available as a temporarymeasure to bridge the transfer during heart transplantationeven without non-thrombogenic substrates. Theinner surface of blood vessels is composed of ‘biomembranes’whose main components are phospholipids.It has been suggested that methacrylate with phospholipidpolar groups might be used at the membrane interface2.1.6. Conclusion – RecommendationPatients with several handicaps require new type biomaterialsto improve their quality of life by assisting, recoveringand/or reconstructing diseased or lost functions/organs.Lack of good bio-compatible biomaterials requires developmentof tissue engineering. For example dialysis membraneskeep more than 500 thousand chronic kidney patientsalive every year. Tissue engineering has limitationsand work is in hand to prepare new functional biomaterials,with sufficiently strong mechanical properties. MPCpolymers are an example. Good scaffolds are also neededfor tissue engineering. Biotechnology, based on genescience offers useful, if difficult methods of producingeffective materials for medical devices and artificial organs.1.2.3.4.5.6.ReferencesDental Biomaterials:Nobuo Nakabayashi and David H. Pashley, Hybridization of Dental HardTissues. Quintessence Publishing Co. Ltd., Tokyo, Berlin and Chicago(1998).MPC related subjects (MPC: see text for explanation):Kadoma Y, Nakabayashi N, Masuhara E, Yamauchi J, Synthesis andhemolysis test of polymer containing phophorylcholine groups. KobunshiRonbunshu J Jpn Polym Sci Tech. 35 (1978) 423-427.Ishihara K, Ueda T, Nakabayashi N, Preparation of phospholipid polymersand their properties as hydrogel membrane. Polym J 22 (1990) 355-360.Iwasaki Y, Ijuin M, Mikami A, Nakabayashi N, Ishihara, K. Behavior ofblood cells in contact with water-soluble phospholipid polymer. J BiomedMater Res 46 (1999) 360-367.Ishihara K, Novel polymeric materials for blood-compatible surfaces.Trend in Polym Sci 5 (1997) 401-7.Ishihara K, Iwasaki Y. Reduced protein adsorption on Novel phospholipidpolymers. J Biomater Appl. 13 (1998) 111-127.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART722.2. Biomaterials: Research and DevelopmentW. Bonfield | Department of Materials Science, University of Cambridge, Cambridge CB2 3QZ, United Kingdom2.2.1. IntroductionBiomaterials are either modified natural or synthetic materials,which find application in a wide spectrum of medicaland dental implant and prosthesis for repair, augmentationor replacement of natural tissues. Some well-knownexamples of the clinical use of biomaterials are total jointreplacement, vascular grafts and heart valves. However,such implanted prostheses are still generally based on materialsselected from engineering practice (designated asfirst generation biomaterials), which combine the ability tobe tolerated by the body with mechanical properties sufficientto withstand anticipated physiological stress. Whileproviding an effective immediate solution for many patients,the outcome is often time-limited. As a consequence,there has been considerable research interest ininvestigating mechanisms contributing to implant-prosthesisfailure and in the potential for developing secondgeneration biomaterials with extended lifetime in thepatient.Biomaterials as an international priority – The importanceof biomaterials in the U.K. has been highlighted in threenational reports. From an users end, a Department ofHealth report [1] identified orthopaedics, dentistry, urology,wound repair, ophthalmology, cardiology and vasculardisease as “clinical specialties where biomaterials play a significantrole in healthcare delivery.” This report complementedan earlier report from the Institute of MaterialsStrategy Commission [2], which commented that “biomaterialssaves lives, relieves suffering and improves the qualityof life for a large number of patients every year.” In addition,the Office of Science and Technology “Foresight” exercise[3] identified biomaterials as a priority topic within thematerials sector and recommended “substantial increasedresources in...a new generation of biomaterials which encourageand enhance the restoration and repair of body tissuefunction.” In the U.S., it is well accepted that the threefields poised for explosive intellectual and commercialgrowth in the 21st century are molecular biology, informationscience and advanced materials [4]. Biomaterialsbridges two of these fields and includes research and trainingcomponents in both basic science and applied engineeringaspects. In Europe, hundreds of thousands of patientsreceive joint replacements, vascular grafts, and heartvalves, each year, with each one having a finite lifetime invivo. With an ageing population, an improved technologybase is essential.A key feature of bioactive, rather than biotolerant, secondgeneration biomaterials is that the interfacial reactionbetween the implant and its surrounding tissue is controlled,with the normal cellular processes being encouraged.Hence, this approach to the design of second generationbiomaterials for particular clinical applications is anexample of in situ tissue engineering, which is an approachparticularly suited to bone replacement. Considerableprogress has also been made in tissue engineering externalto the body; and, through cell multiplication and matrixexpression in bioreactors, it has proved possible to developanalogues of tissues such as skin, cartilage and ligament.Such advances provide a basis for a progression towardsthe ultimate of organ replacement, with benefits in termsof quality of life for patients and in opportunities for associatedindustry.2.2.2. Bone and Skeletal Implants(a) First generation biomaterials for bone and jointreplacementThe functional demands on skeleton – and hence on bone,the major skeletal tissue – are rigorous, with requirementsto enable upright stance, allow locomotion through muscularaction, and provide protection for internal organs.Many people enjoy a lifetime of appropriate skeletal function,but for many other bones and joints become damagedor diseased and require replacement. Arthritis of skeletaljoints - particularly hip and knees - is a major health issueand produces pain and loss of mobility, affecting bothyoung and elderly patients. Osteoporosis, a crippling diseaseaffecting particularly a large number of women overthe age of 50 (and a smaller number of men as well), frequentlyleads not only to disfigurement but to serious bonefractures, such as of the femoral head or acetabulum ofthe hip joint.The seminal work of Professor Sir John Charnley, an orthopaedicsurgeon, produced an artificial hip joint to replacean arthritic hip joint, which was introduced in 1961.Today, hip prostheses based on Charnley’s approach stillconstitute a majority of the 40,000 operations (hip arthroplasties)per year in the UK, 250,000 per year in the U.S.,

and more than 600,000 yearly world-wide. Similar numbersof knee arthroplasties are carried out yearly. The popularityof these procedures notwithstanding, the originalhip operation was designed for a 65+ year-old patient, withthe expectation of prosthesis lifetime of about 10 years.This expectation has been achieved [5], but the progressiveincrease in patient longevity since 1961 and the applicationto younger patients, for whom a shorter prosthesislifetime is obtained (decreasing to rather less than 2 yearsfor a 40 year-old patient [6]), have resulted in an increasingdemand for repeat operations, or revision surgeries. By1995, the percentage of revision hip procedures performedin the U.K. has increased year-by-year to 18% [1] and to acomparable fraction in the U.S. Materials selection forCharnley’s original design was based on first-generationbiomaterials, viz a stainless-steel femoral stem and polyethyleneacetabular cup, both “cemented” (or, more accurately,grouted) in place with poly(methylmethacrylate)bone cement. Similar approaches have been taken for artificialknee joints, with a femoral condylar component ofstainless steel or Co-Cr alloy articulating against a polyethylenetibial insert. Such materials, derived from currentengineering practice in non-biological applications,have in general not themselves failed under physiologicalconditions.However, what was not anticipated was the effect of jointprostheses on the biology of the surrounding bone, whichis living tissue, maintained in an equilibrium state by thecontinuing activity of bone cells (osteoblasts making bone,osteoclasts resorbing bone). The combination of stressshielding of adjacent bone by a prosthesis stiffer than bone,sometimes exacerbated by the inflammatory cellular responseto particulate wear debris, lead to bone loss withtime and an eventual loosening of the prosthesis, 79% ofhip joint failures actually arise from aseptic loosening.These two critical functions of mechanical matching andbiological compatibility must therefore be addressed if thelifetime of the prosthesis is to be increased. Ideally, a onceonlyoperation, with an extended prosthesis lifetime of 25years or more, is required. Such an horizon for hip joint replacementextends to all systems used for bone repair andreplacement in the skeleton – in the treatment of otherjoints such as the knee, in bone cancer, in fractures, and incongenital, traumatic or accumulated bone defects, suchas those arising in osteoporosis and periodontal disease.(b) Second generation biomaterialsThe limitations of first generation biomaterials havestimulated research to develop optimized prostheses forjoint replacement, utilizing biomaterials more closelyresembling the biological template. A radical innovationwas the introduction of synthetic hydroxyapatite,Ca 10 (PO 4 ) 6 (OH) 2 , a calcium phosphate compound whichapproximates to the bone mineral phase that comprisesabout 45% by volume and 65% by weight of human corticalbone. It was demonstrated that, in the body, hydroxyapatite(HA) performed as a bioactive material and promotedbone apposition to the surface rather than encouragingbone resorption. The seemingly innate propensity for implantsto loosen appeared to be reversed, a finding of considerableimportance. The commercial availability of hydroxyapatitepowders led to the introduction of a femoralstem coated with plasma-sprayed hydroxyapatite, to beused as a cementless system for a younger patient group,and spawned a whole industry of HA-coated dental implants.The suggestion is that enhanced early fixation intobone will improve prosthesis lifetime, even though the biomechanicalmismatch of implant and tissue remains.There have been conflicting data as to the long-term efficacyof this approach, but a major clinical trial has recentlydemonstrated a positive outcome for a younger age groupover a 12-year follow-up period [7]. An extensive postmortemstudy of retrieved hip implants in elderly patientshas also revealed that, in that population as well, HA maintainsa more intimate integration of bone with implant [8].Hydroxyapatite has also found clinical application as a genericbone graft material, and much attention is being givento the development of porous HA for tissue guiding,with the prospect of application as bone graft in revisionjoint fracture repair and spinal fusion procedures.Currently, the materials demand is satisfied mainly by usingreal bone, either the patient’s own living bone from othersites (autografts) or dead bone from cadaver or othersources (allografts). Use of a synthetic substitute obviatesthe pain and surgical complexity of autografts and the riskof infectious disease transmission from allografts. The requirementsfor the substitute appear deceptively simple,viz to supply a porous matrix with interconnecting porosity,which promotes rapid bone growth, yet possesses sufficientstrength to prevent crushing under physiologicalloads during the interim bone growth process. A key recentdevelopment has been better understanding of therole of substituted ions in hydroxyapatite in the biologicalresponse. By making synthetic HA more closely resemblethe chemistry of natural bone mineral, it has proven possibleto speed the integration of implanted material intobone. Most promising is selective incorporation of carbonate[11] and silicon [12] ions, which may reduce osseointegrationfrom 28 days to 7 days, a dramatic potential benefitfor patient treatment.MATERIALS: SCIENCE AND APPLICATION73

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART74(c) Commercial innovation in bone biomaterialsA notable example of the innovation of a second generationbiomaterial, is provided by hydroxyapatite-reinforcedpolyethylene composite (now designated HAPEX) foruse as a bone analogue pioneered by Bonfield et al. [9].Modelled on the structure of cortical bone as a naturalcomposite of collagen fibres and apatite, HAPEX wastailor-made to provide matching deformation characteristicsand superior fracture toughness to cortical bone, so asto produce bone apposition rather than bone resorption atan implant surface. The concept was developed with incrementaltesting and processing to produce an optimizedcomposite, which entered clinical trial as a suborbital floorimplant [10]. It was established that HAPEX could betrimmed readily by the surgeon to fit precisely the skeletaldefect and promoted bone bonding without the need forcement.In 1995, HAPEX was licensed by a British company,Smith & Nephew plc, and manufactured by its ENT Divisionin the U.S. for application as a trimmable shaft in amiddle ear implant (replacing the partially or totally damagedor diseased bones which transmit sound from the diaphragmto the inner ear). Following approval by the Foodand Drug Administration, HAPEX was launched at theAmerican Academy of Otolaryngology in late 1995 andachieved immediate clinical take-up with its advantages oftrimmability, providing a precise fit to the individually varyingmiddle ear space, and of bonding to the residual bonybase. Clinical follow-up has indicated a very satisfactoryrestoration of hearing [11]. By 2000, HAPEX had beenincorporated into 22 different designs of middle ear implant,with benefits already to about sixty thousand patients,as well as from wealth creation for the associatedindustry. HAPEX provides a salutary example of tailormakinga second-generation biomaterial for a particularmedical implant, and demonstrates the progression fromlaboratory concept to commercial application in patients.From this base, other implants for bone replacement oraugmentation became possible, with commercial potentialfor a range of minor and major load-bearing applications,including maxillofacial reconstruction, spinal prosthesesand revision hip prostheses.(d) Bone formation and osteoporosisBone is living tissue comprising bone cells (osteoprogenitorcells, osteoblasts, osteocytes, osteoclasts) and a bloodsupply, encased in a strong composite matrix defined byinterwoven fibrous proteins (collagen, adhesion proteins).The matrix is distinguished from that of other connectivetissue by being significantly (45% by volume, 65% byweight) mineralized and organized into lamellae. Osteoblastscells, which derive from progenitor stromal stemcells, are responsible for formation and remodelling of bonematrix, in particular in rapidly developing bone such asthat growing to appose implanted prostheses; osteocytesare osteoblasts which have become embedded in bone matrix.Osteoclasts, which arise by differentiation from hemopoieticstem cells, are responsible for resorption ofbone, largely through local acidification, which dissolvesbone mineral and permits a range of proteolytic enzymesto destroy the associated bone matrix. Living bone is continuallyundergoing remodelling from the opposing actionof osteoblasts and osteoclasts.Bone matrix is natural composite biomaterial with a complexhierarchical structure. It comprises bundles of collagenfibres which have been infiltrated by a crystalline mineralphase, resembling synthetic hydroxyapatite,Ca 10 (PO 4 ) 6 (OH) 2 , but in which some of the tetrahedral[PO 4 ] 3- phosphate groups have been replaced by planar[CO 3 ] 2- carbonate group, F- or Cal- ions can substitute forsome [OH] - groups, and the crystal structure more closelyresembles that of the hexagonal fully fluorine-substitutedfluorapatite. As the carbonate content is increased, HAcrystallites gradually adopt a plate-like morphology. Electronmicroscopy studies by Professor Hobbs’group and othershave shown that collagen and the apatite mineral formcontinuous, independent, interpenetrating networks.Cortical bone is the dense bone (~10% internal porosity)making up the shafts of long bones like the femur (thigh)or tibia (shin). Cancellous – or trabecular – bone has aninterconnecting porous architecture (50-90% porosity)made up of curvilinear struts called trabeculae; it appearsat the ends of long bones – where hip and knee implantsare fixed – and in the vertebral body. In the process of newbone formation, for example adjacent to femoral stems inhip implants, osteoblasts migrate to the wound site, attach,and within days release collagen which forms an immediatefibrous template for mineralization to form newbone matrix. The rate and direction of bone matrix formationand resorption is influenced by stress in the bone arisingfrom loads imposed by gravity and muscle action, whichis why bone atrophies in idle limbs or in space.Osteoporosis is a disease state in which resorption of bonematrix takes place at a faster rate than creation of new bonematrix, so that the normal remodelling balance is upset,leading to a decrease in bone density and strength. TheWorld Health Organization has defined the diagnostic criterionfor osteoporosis to be bone with a bone mineral densityof more that 2.5 standard deviations below the youngadult level. The two most common types of fractures associatedwith osteoporosis are those of the hip (proximal femur)and spine (vertebrae). Each year in the United States

there are 250,000 age-related hip fractures, with an estimatedhealth care cost approaching $10 billion and700,000 age-related vertebral fractures, with costs of £1billion. In Britain, the equivalent overall costs approach£2 billion. Hip fractures in the elderly are associated withexcess mortality rates of 12-20% above that which wouldnormally be expected. Almost all hip fractures are associatedwith trauma, such as a fall, while most vertebralfractures are the result of the activities of daily living.Whereas in the proximal femur the cortical bone carries ahigh proportion of mechanical load, particularly in the midneckand shaft, in the vertebrae, most of the load is carriedby trabecular (cancellous) bone. Between the ages of 30and 80 years, bone mass generally decreases by 1%/year;in patients with osteoporosis, trabecular bone loss can decreaseby up to 9%/year. On average, women lose abouthalf of their trabecular bone over their lifetime, correspondingto a 75% reduction in strength. Clearly, changesin the mechanical properties of osteoporotic trabecularbone increase the risk of fracture.2.2.3. Prospects for Tissue EngineeringBioactive composites for bone substitutes, such asHAPEX provide an approach to skeletal regeneration inwhich the implant surface provides a favourable site forthe recruitment of cells from the surrounding biologicalenvironment, with the subsequent cellular processes leadingto the expression of matrix and tissue formation. Incellular or tissue engineering, such cells are cultured outsidethe body to form tissue that can be used subsequentlyfor tissue repair. The primary advantage of a tissue substituteobtained by this route is that some or all of the biologicalgrowth factors would be immediately available,rather than needing to be recruited. Such an approach hasparticular appeal, for example, in the potential repair ofregions of healthy cartilage damaged by injury, as a moreconservative treatment than that of total joint replacement.There are enormous intrinsic challenges in the productionex vivo in a bioreactor of tissue comparable (in terms ofcomposition and properties) to normal natural tissue.Other key challenges are to develop a source of cartilagecells (chondrocytes) with a favourable immune response,to design an appropriate method of fixation, and to provideeffective storage. With respect to cartilage, companiessuch as Advanced Tissue Sciences in the U.S. have takenthe pioneering work of Langer [12] through to prototypecartilage grafts, which approach (but do not yet equal) thecomposition and properties of the natural tissue. Oneexciting prospect is of conditioning the cartilage cells inculture in the bioreactor by mechanical stimulation, so asto produce an equivalent or even superior tissue. Whenavailable, a competent cartilage graft will have enormousimplications for the early treatment of defects in articularcartilage, both to repair damage in healthy tissue and inthe first stages of arthritis.For other tissues, such as skin, both in vivo and ex vivoapproaches have been developed. The seminal work ofYannas [13] on the biomechanics of skin provided the basisfor his development of a porous polymer-based scaffold torecruit fibroblasts in vivo for skin regeneration. Alternatively,tissue-engineered skin from a bioreactor is now inclinical use for the treatment of diabetic foot ulcers.For bone tissue engineering, there is a direct link from theresearch on porous hydroxyapatite, which could provide asuitable matrix delivery system for osteoblasts or precursorstem cells. In the former case, such an approach wouldprovide an autograft equivalent to bone grafting, withoutthe need for a second operation. An exciting prospect inthe latter case is the production of both bone and cartilagethrough cell differentiation locally directed by scaffoldsand scaffold chemistries, so as to produce a mini-implantof cartilage already in place on bone, e.g. a replacementacetabulum of bone complete with its cartilage lining,which would eliminate the considerable difficulty of fixingcartilage to bone in vivo. A complementary approach is tostimulate osteoblast recruitment, e.g. by local delivery ofparathyroid receptor agonists through prior transfection ofthe PTH gene into local fibroblasts.2.2.4. General ConclusionsFirst generation biomaterials have made possible theexisting procedures for bone and joint replacement now incurrent use, which provide restored mobility and relieffrom suffering for many thousands of patients on a worldwidebasis. However, the advent of novel second generationbiomaterials and the prospects for tissue engineeringoffer the potential for a broader range of longer lastingimplants and prostheses, with benefit both to patients interms of quality of life and to the associated industry inwealth creation.MATERIALS: SCIENCE AND APPLICATION75

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART762.2.5. Research Priorities for Europe• More European programmes of a scale to compete withmajor developments in the U.S. and Japan (and potentiallyChina).• At the same time, develop collaborative programmeswith key centres in the U.S. (following the CambridgeUniversity-MIT model).• Develop a distinctive materials science approach toembrace the continuum from gene to protein to cell tobiomaterial to medical device.• Emphasize the innovation of novel biomaterials and tissue-engineeredartefacts, based on the biological template,for tissue and organ replacement.• Develop an understanding of the mechanisms controllingthe interaction of cells with second-generation biomaterialsand third generation tissue engineering scaffolds.• Encourage the progression of novel biomaterials fromthe laboratory to distinctive clinical applications inpatients by entrepreneurial technology transfer.References1.2.3.4.5.6.7.8.9.10.11.12.13.R & D Priorities for Biomaterials and Implants ([U.K.] Department ofHealth, 1996).Materials Technology Foresight in Biomaterials ([U.K.] Institute of Metals,1995).Technology Foresight ([U.K.] Office of Science and Technology, HMSO,1995).P. Chaudhari, M. C. Flemings, et al., Materials Science and Engineeringfor the 1990s: Maintaining Competitiveness in the Age of Materials([U.S.] National Academy of Sciences, Washington, D.C., 1990).H. Malchan and P. Hervert, Prognosis of Total Hip Replacement (AmericanAcademy of Orthopaedic Surgeons, 1998).D. J. Sharp and K. M. Porter, Clin. Orth. 201 (1985) 51.R. Geesink, International Union of Materials Research Societies Conference,Beijing, China (1999).M. J. Coathup, G. M. Blunn, N. Flynn, C. Williams and N. P. Thomas, SixthWorld Biomaterials Congress Transactions 1 (2000) 185.W. Bonfield, et al., Biomaterials 2 (1981) 185.R. M. Downes, et al., Bioceramics 4 (1991) 239.J. L. Dornhoffer, Laryngoscope 108 (1991) 531.R. Langer, et al., Principles of Tissue Engineering (Academic Press, 1997).I. V. Yannas, J. F. Burke, D. P. Orgill and E. M. Skrabut, E. M., Science 215(1982) 174-76.2.3. Biomaterials: Medical ViewpointL. Sedel | Hôpital Lariboisière, Université Paris 7, UFR Lariboisière-Saint-Louis, 75475 Paris Cédex 10, France2.3.1. IntroductionThe field of biomaterials – materials working under biologicalconstraints – is rapidly expanding. It is considered thatthis domain represents 2 to 3 percent of the overall healthexpenses in developed countries. For example Francespends every year 30 to 40 billions of French francs. Worldexpenses could be estimated at 100 billions of dollars.This field covers a lot of different materials: cardiac artificialvalves, artificial vessels, cardiac stimulators, stents, artificialhips, knees, shoulders, elbows, materials for internalfracture fixation, scoliosis treatment, materials for urinarytract reconstruction, artificial crystalline, skin, earsossicules, dental roots and so on. Many different materialsare involved: metals i.e. titanium alloy, cobalt chromium alloy,stainless steel, tantalum, ceramics i.e. alumina, zirconia,hydroxyapatite, calcium carbonate, plastics i.e. polyethylene,polymetylmetacrylate, polyurethane and alsocomposites: carbon-carbon, natural materials i.e. coral, nacre,bovine collagen and so on.Some new fields are now explored such as cell therapy orgrowth factors therapy that need some supporting materialwhich is a very expending field.2.3.2. State of the Art on Biomaterials ResearchIt is an interdisciplinary field. Many different experts mustwork together. Mechanical engineers, material scientists,chemists, biologists, medical doctors, and surgeons haveto meet in interdisciplinary teams dedicated to this subject.They must also keep in touch with their originatedfield in order to be aware of up-to-date research in theirspecific domain.This interdisciplinary field of applied research is verylinked to industry. Industry is very aware of quick developmentand income, governments and administration areaware of controlling expenses, prices and security. Academicresearch is not developed, neither in Europe nor in

the U.S. Interdisciplinary work could result in a seriousbreakthrough not only for insuring security and comparisonbetween different materials but also to understand severalbasic problems that are totally uncontrolled. For example,the way living tissue react to foreign materials, what arethe law of reject or acceptance, how living cells react tomechanical changes in their environment, how could it bepossible to enhance tissue regeneration, tissue fixation onartificial surfaces, how to develop materials that will notbreak under mechanical stresses. Many problems are alreadysolved but as a new field, few institutes or nationalsciences foundation are aware of that. Since this is not arecognized discipline, there are very few structured teams,few facilities, limited amount of public money, no positionavailable if no discipline exists and so on.This could be one of the major issues at an European levelto promote this field of research in different scientific communitieslike mechanical engineers, physicists, chemists,biologists.2.3.3. Future Expected BreakthroughsAn effort might be made in developing overlapping andlinks between the different scientific communities thatmight be needed to develop projects. Subjects are numerousfrom simulation methods, mechanical as well asnumerical, new adapted materials, phenomenological researchon cells, tissues, organs behaviour when in contactor replaced by some artificial materials, functionalized materialsthat acquire a special biological affinity to answer aspecial question: anticoagulant materials on plastic surface,antimicrobial agent, anticancer drugs and so on. Exactmechanisms of cells linkage to artificial surfaces couldhave a major implication in material acceptance. At thetime of cell therapy, there must be some teams implicatedin tissue engineering who will work on stem cells that couldbe cultivated and then growth on different artificial supportsto replace a damaged tissue: bone, skin, ligament,cardiac wall and so on. At the time of new products likegrowth factors are supposed to provide enhanced healingfactors, materials for their delivery in selected tissues isalso of major relevance.Countries must also organise the results appraisal at a governmentlevel: quality control, patient register that allowsto follow every implanted material and to know exactly theoutcome of these implanted devices. This permits also toinsure security and to quickly remote a product when failuresare identified.2.3.4. Guidelines, Orientation and Priorities of FutureEuropean ResearchAn EC action might take many directions. One could beto foster and promote this scientific field and develop basicresearch in academic institution. Public grants for basicresearch in conjunction with some mixed public andindustrial funds on more applied fields might be promoted.Selected fields of interest might be considered like cellsand artificial surfaces, mechanical modelling of living cells,quality controls of biomaterials including their behaviourafter human implantation, ceramic dedicated to living materialsreplacement.These actions at a European level could permit to identifyinterdisciplinary teams dedicated to the field and give themthe possibility to work on a long term basis. Any limited actionas it was done in the past were not strong enough norprolonged and then after an initial enthusiasm, the teamsjust broke down.In Europe there is an old tradition of excellent basic researchin different fields that could be involved: engineering,chemistry, biology, materials science. Many researcheswere already developed in weapons, transports, and nuclearindustry. The biomaterials field represents a fieldwith very important consequences for the population. Anybiomaterial that fails could be the reasons for death, disability,further surgical operation and this might convinceour politics that this field might really be supported as astrategic one.2.3.5. U.S., Japan, EU PositionsRules are quite different for different countries. In theU.S., the Food and Drug Administration is very strictabout new materials to be applied in human.In Europe, these materials must have a EU mark that is givenby some institutions that have been labelled by each governmentto deliver this mark. Then the product can be soldin every EU country and remains under the law of eachcountry. For example in France, a law called “Huriet Law”describes the process of human experiments that has to beaccepted by a technical committee before this material canbe sold. In Japan, the field is quite developed because somecultural specificity forbids the use of human material ororgan transplant. This explains why some materials likeceramics or cells supporting material are quite in advance.Anyway, the market is actually dominated by the U.S. Evenif their products are not the best, their implications in re-MATERIALS: SCIENCE AND APPLICATION77

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART78search and the strength of the industry is a way topromote their products, even if not totally up-to-date. Forexample many advances are originated in UK, Germany,France, Switzerland but finally developed and marketedin the U.S.It is also true that the major pharmaceutical companiesfrom Europe like Aventis, Bayer, Sanofi, Synthelabo andothers are not involved or no more involved in this fieldfor many historical reasons.2.3.6. ConclusionsBiomaterials is one of the growing field in health caresystem in the world. Europe is no longer on the road fordifferent reasons explaining why our exchange balance isnegative. A massive input to foster and promote basicacademic researches in the field could modify the scope.Europe has all the expertise to do so. Only political will ismissing. Selecting this field as strategic and actingaccordingly could be the answer. In order to organize thisfield, a bunch of experts might be nominated representingdifferent medical areas like cardiovascular surgery,orthopaedics, ENT, ophthalmology, materials science.These interdisciplinary teams might work together inorder to propose common actions, to nominate experts toselect the best proposal and also to organize some centresof excellence in some of these fields that could handlesome of these missions such as: evaluation, development,quality controls, basic research and link with the industry.One centre by area of interest and by major countriescould be a bunch mark to start this effort. Also coursesdedicated to biomaterials and organized at a Europeanlevel could be organized.2.4. Biomimetic Materials and Transport SystemsR. Lipowsky | Max-Planck-Institut für Kolloid- und Grenzflächenforschung, 14476 Potsdam, GermanySummaryBiological cells have amazing materials properties, which arebased on their macromolecular and supramolecular (or colloidal)building blocks. During the last decade, much progresshas been made in order to identify these different componentsand their interactions. The next step will consist in theintegration of these different components into higher-levelsystems. Some examples for such biomimetic systems are:supramolecular architectures containing membranes andpolymers; polymer networks as models for the cytosceleton;biomimetic mineralization; transport via molecular motors;biomimetic recognition and signal transduction.These research activities are interdisciplinary and involvethe combined efforts of physicists, chemists, molecularcell biologists and bioengineers. The biomimetic modelsystems, which will arise from these efforts, have manypotential applications in bioengineering, pharmacologyand medicine.There are various places in Europe, which already pursuerelated research on a local scale. What is still missing, however,is an initiative, which combines these efforts on theEuropean scale. Such an initiative is necessary in order tocompete with the science community in the U.S. whereseveral “BioX”-centres are currently being set up.2.4.1. Introduction: The Goals of BiomimeticsBiological cells are built up from macromolecules andsupramolecular assemblies (or colloids) in water. Both theintracellular architectures and the interactions between cellsare based on soft and flexible nanostructures, which are multifunctionaland highly intelligent materials. In addition, cellsare able to build up hard materials in the form of biomineralsand to control their morphology on the nanometre scale.All cells contain similar macromolecules but differenttypes of cells can survive in very different environments.Indeed, cells can live in boiling water, in strong acids, atthe low temperatures of the Antarctic, and under the enormouspressures of the deep sea. These different adaptations,which are based upon different supramoleculararchitectures, demonstrate the wide range of possiblematerial properties of these architectures.

Another intriguing aspect of biological cells is that theycontain a large variety of very efficient transport systems.The latter systems are based on motor proteins or molecularmotors, which transform chemical energy into mechanicalwork. These nanoengines are responsible for the transmembranetransport of ions and macromolecules, for theregulated adhesion and fusion of membranes, for the intracellulartransport of vesicles and organelles, for cell divisionand cell locomotion.Research on biomimetic materials and transport systemshas four goals:• Understanding the material and transport properties ofbiological cells and tissues. Since these latter systemsare very complex, such an understanding can only ariseif one focuses on certain aspects of these structures.Thus, one is led to the• Construction of model systems to which one can applythe experimental and theoretical methods of physics andchemistry. The coevolution of experiment and theory isa necessary condition in order to transform vague ideasinto useful knowledge.• The knowledge obtained from the biomimetic modelsystems can then be used in order to develop new typesof designed materials which are biocompatible andwhich have defined physical, chemical or biologicalcharacteristics.• Applications of these biomimetic materials in bioengineering,pharmacology and medicine.2.4.2. State of the ArtThe structural organization within biological cells hasmany levels. As one goes “bottom-up”, i.e., from small tolarge structures, the first three levels are: (1) the level ofmacromolecules (or copolymers) which have a backboneof monomers connected by covalent bonds; (2) the level ofsupramolecular assemblies of many similar molecules, theformation of which is governed by noncovalent forces suchas the hydrophilic or hydrophobic interactions with water;(3) the level of complex architectures which contain differenttypes of building blocks and/or different types of assemblies.These different levels will be discussed in thefollowing subsections.(a) Recent developments: macromoleculesThe macromolecular components of the cell (proteins,nucleic acids, polysaccharides, lipids) are known for a longtime. All of these macromolecules are copolymers, whichare built up from a certain number of different monomersor building blocks. In addition, the three-dimensional conformationof these biopolymers is determined, to a largeextent, by the water solubility or hydrophilicity of thesebuilding blocks. From the viewpoint of material science,one simple and useful property of biopolymers is that allmembers of the same molecular species have the samelength. In contrast, synthetic polymers always exhibit somelength distribution or polydispersity.In the last decade, new synthetic methods have been developedwhich allow the construction of hybrid moleculesconsisting of biopolymers coupled to synthetic ones. Inthis way, one can design new biomimetic polymers, whichcombine the properties of both the natural and thesynthetic component. In addition, new experimentalprocedures, so-called “single molecule methods”, havebeen established by which one can determine the physicalproperties of single macromolecules.On the one hand, one can label these molecules by a fluorescentprobe and then track their motion both in solutionand bound to a sheet-like membrane or rod-like filament.On the other hand, one can firmly anchor them at asolid surface and then probe individual macromoleculesby various experimental methods. Using optical methods,for instance, one can directly observe the thermally excitedtransitions between two different conformations ofRNA strands. One may also use the tip of an atomic forcemicroscope in order to pull at a single copolymer, which isanchored to a solid surface. In this way, one can determinethe functional relationship between the force andthe linear extension of the molecule. These force-extensioncurves are rather reproducible and, thus, reflect theforces, which determine the three-dimensional conformationof the polymer.Fig. 2.2. Cartoon of two molecular motors, in this case two kinesins,bound to a microtubule filament. The microtubule has a thickness of25 nm. Each kinesin walks along the filament by making steps of 8 nm.MATERIALS: SCIENCE AND APPLICATION79

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART80A third area where single molecule methods have led tomuch insight is the active movement of molecular motorsalong filaments. For some cytoskeletal motors (see Fig. 2.2)it has been possible to resolve single motor steps, which areof the order of 10 nanometres. In the cell, these motorsare responsible for the directed transport of vesicles andorganelles over tens of micrometres or even centimetres.(b) Recent developments: supramolecular assembliesIf one looks into a typical animal or plant cell, one sees twotypes of supramolecular assemblies which determine thespatial organization of the cell over a wide range of lengthscales: (i) compartments bounded by sheet-like membranesand (ii) networks of rod-like filaments. These twotypes of structures are displayed in Fig. 2.3 and Fig. 2.4.Both structures are assembled on the molecular scale, i.e.,on the scale of a few nanometres, but are able to organizemuch larger spatial regions up to tens of micrometres!Biomembranes are highly flexible and, thus, can easilyadapt their shape to external perturbations. In spite of thisflexibility, they are rather robust and keep their structuralintegrity even under strong deformations. This combinationof stability and flexibilityis a consequence of their internalfluidity. This was first realized in the context of lipidbilayers, which are the simplest biomimetic membranes.10mFig. 2.4. Cytoskeleton of a large animal cell. This network of filamentsis primarily built up from microtubuli, which emanate from the centreand actin filaments at the periphery of the cell.Fluid membranes have unusual elastic properties, whichdetermine their morphology. These properties are nowunderstood in a quantitative way using (i) mesoscopic modelswhich describe the membranes as elastic sheets and(ii) models with molecular resolution which can be studiedby computer simulations and can be used to relate theelastic parameters with the molecular interactions.The stability of lipid bilayers makes it possible to isolatethem and to manipulate them in various ways: one cansuck them into micropipettes, attach them to other surfaces,and grab them with optical tweezers generated byfocused laser beams. These membranes are even self-healing:if one pinches small holes into them, the holes closeagain spontaneously.Fig. 2.3. The spatial organization of a typical animal cell is based onmembrane-bounded compartments. The diameter of the cell is of theorder of 20 micrometres.In the last couple of years, new types of biomimetic membraneshave been constructed. One example is provided bybilayers of amphiphilic diblock copolymers. Both artificialand hybrid copolymers have been found to undergo spontaneousbilayer formation. The underlying mechanism isthe same as for lipids. Another type of biomimetic membraneis provided by polyelectrolyte multilayers. These multilayersare constructed in a layer-by-layer fashion whereone alternatively adds negatively and positively chargedpolyelectrolytes onto solid templates. These multilayersform dense polymer networks, which are reminiscent ofthe filament networks close to the outer plasma membraneof cells. These new types of biomimetic membranes have alarge potential for applications as drug delivery systems.

In addition to the soft and flexible assemblies discussed sofar, biomimetic research has also produced hard materialsin the form of biomimetic minerals. These minerals aretypically built up from rather simple building blocks suchas hydroxyl apatite or calcium carbonate. However, biologicalcells are able to control the detailed morphology ofthese minerals. As a result, the same building block suchas hydroxyl apatite leads to rather different materials suchas teeth and bone. It has been recently shown that suchprocesses can be mimicked, to a certain extent, by growingthe minerals in the presence of organic additives suchas synthetic copolymers in aqueous solution.(c) Recent developments: complex architecturesThe next level of complexity consists in supramoleculararchitectures which incorporate different types of buildingblocks and/or which contain different types of supramolecularassemblies.Several attempts have been made to built up complex architecturesconsisting of rodlike filaments within membranecompartments. It has been demonstrated that both actin filamentsand microtubules can be polymerized within lipidvesicles. This can be directly observed in the optical microscopesince the growing filaments induce morphologicaltransformations of the vesicles. In the case of actin, two differentprocedures have been realized. One of these proceduresled to shells, which are reminiscent of the cytoskeletoncortex, the other to protrusions, which resemble microvilli.The layer-by-layer construction of polyelectrolyte multilayersmakes it possible to incorporate layers of differentspecies of polyelectrolytes and/or of other types of colloids.In this way, one can construct complex multilayers, whichrepresent multifunctional interfaces.Complex architectures may also be constructed usingchemically structured surfaces. Indeed, the multifunctionalinterfaces of biomembranes arise from the lateralorganization of these membranes into specialized membranedomains. New techniques have been developedwhich make it possible to chemically structure solid surfaceon the nanometre scale. These structured surfacescan be used to build up supramolecular architectures witha defined lateral organization.There are many challenges for biomimetics on the supramolecular(or colloidal) scale. One important and generalgoal is to gain improved control over the structure formationand over the morphology of the supramolecular assemblies.In particular, one would like to construct biomimeticsystems, which undergo reversible transformationsand, thus, can be switched forward and backward betweendifferent types of assemblies or between different types ofmorphologies. Likewise, one would like to incorporatesuch reorganisable structures as subsystems into largerarchitectures.Future research projects, which will lead to such an improvedcontrol include:• Construction of spatial patterns of filaments. This couldbe achieved, e.g., by anchorage to chemically structuredsubstrates;• Controlled assembly and disassembly of filaments;• Lateral organization of membranes into well-defineddomains;• Biomimetic recognition systems or biosensors based onimmobilized membranes;• Controlled formation of membrane buds mimicking thecellular processes of endocytosis and exocytosis;• Model systems for the fusion of membranes;• Minerals with defined morphologies on the nanometrescale;• Biomimetic transport systems based on filaments andmolecular motors in open and closed compartments. Thelatter type of systems is inspired by the directed transportas found in the axons of nerve cells, see Fig. 2.5.MATERIALS: SCIENCE AND APPLICATION812.4.3. Future PerspectivesFig. 2.5. All microtubule filaments within an axon have the same orientation.Cytoskeletal motors (indicated by small “feet”) are responsiblefor the directed transport of various particles along these filaments.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGARTA more ambitious long-term goal would be to combinebiomimetic sensors and motors in order to get modelsystems for biological signal transduction. Thus, one mayenvisage autonomous nanorobots, which receive physicalor chemical signals from their environment and respondto this information with some “action”.In the very long run, research on biomimetic systemscould lead to construction kits by which one can createartificial cells. At present, this vision must still be regardedas science fiction.References1. R. Lipowsky and E. Sackmann (Eds.), Structure and Dynamics of Membranes.Handbook of Biological Physics, Elsevier, Amsterdam (1995).2. B. Mulder, C. F. Schmidt, and V. Vogel (Eds.), Materials Science of theCell. Materials Research Society, Symposium Proc. 489, MRS, Warrendale(1998).3. R. Bar-Ziv, E. Moses, and P. Nelson, Dynamic Excitations in MembranesInduced by Optical Tweezers, Biophys. J. 75 (1998) 294-320.4. P. Bongrand, Ligand-Receptor Interactions. Reports of Progress in Physics62 (1999) 921-968.5. A.D. Mehta, M. Rief, J.A. Spudich, D.A. Smith, and R.M. Simmons,Single-Molecule Biomechanics with Optical Methods, Science 283(1999) 1689-1695.6. D. Paris, I. Zizak, H. Lichtenegger, P. Roschger, K. Klaushofer, and P. Fratzl,Analysis of the hierarchical structure of biological tissues by scanningX-ray scattering using a micro-beam, Cell Mol Biol 46 (2000) 993-1004.822.5. Materials Science in CatalysisF. Schüth | Max-Planck-Institut für Kohlenforschung, 45470 Mühlheim an der Ruhr, GermanyR. Schlögl | Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin, Germany2.5.1. IntroductionCatalysis is the technology, which allows to increase therate and selectivity of a chemical reaction by a substance,which is, to a first approximation, not consumed duringthe reaction. Catalysis has a major impact in the chemicaland related industries, as all chemicals, which are raw orintermediate products for other industries are obtainedusing this technology. The overall catalyst market is around10 billion € (Fig. 2.6), the revenue generated by processesusing catalysts is difficult to estimate, but exceeds the catalystmarket probably by factor between 100 and 1000, i.e.is somewhere between 1.000 and 10.000 billion €. In addition,catalytic processes are also ecologically superior tonon-catalytic processes in that they typically consume lessraw materials and energy. Even slight improvements in catalystperformance can translate to big savings in raw materialsand energy in large-scale processes, since there aremany base chemicals, which are produced via catalyticroutes in volumes exceeding 1 million metric tons per year.environmentalpolymerrefinerychemicalA large potential for catalysis exists in fine chemicals production,where many conversions are still carried out stoichiometricallywith large amounts of waste being producedor toxic reaction routes (chlorinated hydrocarbons as intermediates)being technological practice. Replacing suchreactions with catalytic steps would lead to tremendousimprovements.Catalytic reactions are not only important in the chemicalindustries, but also in other sectors of the European economy.Table 2.1. gives examples for the importance ofcatalysis in different fields and also addresses some of thechallenges, which still exist.Fig. 2.6. Catalyst market (total around 10 billion €) and division intodifferent application fields.

2.5.2. State of the ArtSince materials science deals with solids, this section willprimarily focus on conversions, which are catalyzed by solidcatalysts (“heterogeneous catalysis”). This correspondsto the fact that the majority of the industrially used catalyticconversions are heterogeneously catalyzed reactions.However, homogeneous catalysis and biocatalysis are increasingin importance, and one of the trends in catalysisresearch is the merging of these different fields. It can thusbe expected, that homogeneous and biocatalytic reactionswill also be increasingly applied in industry.Going beyond this heuristic knowledge, an understandingof the catalytic action and the principal steps in severalimportant reactions has been achieved. There are toolsavailable for studying well defined model systems, suchas the surface science techniques to investigate singlecrystal surfaces under high vacuum conditions or the varioustechniques developed to study elementary steps inhomogeneously catalyzed reactions. Also the theoreticaltreatment of catalysts and catalysis is developing fast. It isnow possible to calculate interaction energies of moleculeswith model surfaces, in some cases even reactionpathways have been predicted (Fig. 2.7).MATERIALS: SCIENCE AND APPLICATIONScientifically, catalysis might on a first glance appear tobe a mature science: Based on empirical knowledge acquiredover decades, scientists and practitioners haveguidelines how to select a catalyst for a given reaction – atleast for some generic classes of reactions. Over the lastyears, this toolbox has been supplemented by the adventof high throughput experimentation in catalysis research,which accelerates the rate at which experiments can beperformed, and expands the parameter space of conditionsand catalyst compositions, which can be explored.The empirical knowledge base has, however, reached itslimits for many applications, as decades of research haveto be invested for a marginal improvement of the performance(e.g. in selective oxidation catalysis).Improved catalysts and processesFig. 2.7. State of the art in catalysis research. Starting from upper left,then going clockwise: Modelling of solid-reactant interaction(MSI), regular porous silica with a surface area of 800 m 2 /g (MPI fürKohlenforschung), in situ EXAFS spectra of MoO 3 catalyst (Fritz-Haber-Institut), in situ atomic force microscopy of adsorbed oxygen (Fritz-Haber Institut), 49 channel high throughput reactor for acceleratedcatalytic testing (MPI für Kohlenforschung).83Industry segment Application example Exemplary problemChemical Various Small alkane oxyfunctionalizationPetroleum Cracking, reforming, alkylation Replacing sulfuric acid in alklyationetc.Energy Selective catalytic reduction NO x decomposition, high temperature stable combustionof NO x , catalytic combustion, catalysts, photochemical hydrogen generationfuel cell• Automotive Fuel cell, DeNO x Fuel processor for fuel cell, lean NO x• Electronics Fuel cell for mobile applications Fuel cell catalystsTable 2.1. Catalytic reactions in various application fields.However, although a high degree of knowledge in catalysishas been achieved, there are still many problems of afundamental nature unsolved. There is, for example, noverified understanding of the local structural and electronicrequirements of a surface on a general basis. Fundamentalwork to solve these problems are the long-term

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART84trends in catalysis research, and these problems andtrends will be described in the following.2.5.3. Expected BreakthroughsThe ultimate vision of catalysis research is the ability tode novo-design a catalyst for any given reaction (Fig. 2.8).There are many “dream reactions” which so far cannot beperformed on a commercial scale or even on the laboratoryscale, although these reactions should in principle bepossible. Catalytic routes could make such reactions possible,if design principles for catalysts were available. Thisgoal will not be reached on a short time scale of severalyears but is probably still decades away. In the meantime,high throughput experimentation will be an importanttransition technology to discover novel catalysts for burningcatalytic problems which need to be solved, for instanceto allow the introduction of a fuel cell based transportationsystem.1. 2. 3.Fig. 2.8. Ultimate goal in catalysis research: 1. Calculate catalystrequirements for a desired transformation from first principles.2. Rationally synthesize catalyst with calculated characteristics,3. Use in catalytic process.To approach the ultimate goal of a catalyst design, fundamentalcoordinated research is necessary, since isolatedactivities are mostly focused on special reactions fromwhich only limited generic information can be derived.Typically, research in this field is highly interdisciplinary,since chemists, physicists, theoreticians, and engineersare necessary to tackle the fundamental questions from alldirections. On the way to a catalyst design, methodologieswill have to be developed which will not only help to advancethe field of catalysis, but will also have effects in other,related fields of research. In addition, it can be expected,that from some exemplary catalytic problems, whichare chosen to develop the methods, breakthrough discoveriesfor specific catalytic reactions will be made.2.5.4. Roadmap of European Catalysis ResearchCatalysis science is, despite its interdisciplinary character,usually split between physical chemistry, inorganic chemistryand chemical engineering, which is not a uniting disciplinefor catalysis, as e.g. in the U.S.Industrial catalysis research is occluded behind huge wallsto protect intellectual property. Today’s catalysis technologyis predominantly based upon empirical findings, andexisting plants contain many proprietary key features essentialfor commercial success. It is almost impossible todo process-relevant research in co-operative structures.The progress of fundamental knowledge in the last decadeallows, however, to define a few key actions to be taken inorder to move forward in a faster way in this fundamentaltechnology. The turnover times in catalysis technology isvery long with 15 to 20 years and the readiness of industrialusers for new technology is very limited which resultsfrom the enormous risks related with the huge capital investmentsand the technological and safety uncertaintiesassociated with large scale production facilities. All thiscould be tremendously more efficient and developmentbenefits could be brought to bear on economics and environmentmuch faster, if the development basis of new catalysistechnology would be more rational and more transparentthan the present empirical search.The following description of key areas of possible Europeanresearch engagement is based upon the idea to focusefforts on generically relevant issues and to abstain fromsupporting individual reaction types by again empirical optimizationstrategies.(a) Bridging the gaps between model studies and realworld catalysisThere are well-developed tools available to study catalyticreactions with surface science techniques on model surfaces.There are also some techniques, which are suitablefor an in situ analysis of the catalyst under process conditions.However, the gaps between these two approaches –the so-called pressure gap and the materials gap – are substantial.It is generally impossible to transfer or extrapolateresults obtained under UHV conditions to the catalyticreaction under process conditions, because the partialpressures of the reagents and thus their internal interactionsdiffer by many orders of magnitude, and, possiblymore severe, the catalytic surfaces are not identical underUHV and at higher pressures.It appears that for many catalytic reactions the real structuresof the catalysts, i.e. their defects, particle shapes and

other properties, are most decisive. This, however, will bedifficult to mimic in a model system. Great efforts aretherefore needed to bridge this gap between model studiesand real world catalysts, to analyse the real structuresof solids and to develop more powerful in situ techniques.To study catalytic reactions under process conditions inorder to understand the influence of these factors on theperformance of a catalyst. These allow to study catalyticreactions under process conditions in order to understandthe influence of the reaction conditions on the performanceof catalysts.Such studies, especially the analysis and the understandingof the defect structure of solids, are not only importantin catalysis research but have far wider implications, sincefor almost any material the defect structure could determine– or at least influence – the performance of thematerial in applications.(b) Understanding catalytic reactions on an atomic levelFor a true understanding of catalytic reactions, means haveto be developed to study such reactions on the atomic scaleand to describe the processes on catalytic surfaces theoreticallyfrom first principles. First steps in this directionhave been taken, and reaction rates measured by directobservation with atomic resolution (Fig. 2.9) correlate wellwith macroscopically determined reaction rates. However,these successes are so far limited to simple reactionson model metal surfaces.be and what real structure it should have, there is at presentno rational synthesis strategy available, which could beused to develop a preparative route to a complex solid on alarge scale. Today, solids formation is only poorly understoodon an atomic level, and – as in the development ofcatalysts nowadays – the synthesis of solids with desiredstructure and properties is largely empirically driven.Therefore techniques to analyze the steps leading to solidsformation on an atomic scale need to be developed, so thatdetails of nucleation and solids growth can be understood.A full integration of experimental and theoretical approachesis necessary to this means.Since modern catalysts are typically multicomponentsystems, not only nucleation and growth of single phasesneed to be understood, but also the development of suchcomplex solids. For instance, in the case of supported catalysts,the development of the real structure and the interactionof support and solid are only sketchily understood,although this drastically influences the performance of acatalyst.MATERIALS: SCIENCE AND APPLICATION85Parallel to the development in experimental techniques,answers to the nature of the elementary steps in catalyticreactions will come from high-end ab initio theory. Suchtheory has reached a state, where close interactionbetween theoreticians and experimentalists is fruitful forboth sides. First calculations on the course of chemicalreactions on surfaces have been performed and providemeaningful data. Invaluable are the contributions of theoryin predicting stability and dynamics of catalyst surfaces(oxides) and the interactions of these surfaces with the gasphase (dynamics of termination, sub-surface compoundformation).Also here fundamental understanding will not only be importantin catalysis, but the methods developed to studysurface reactions on the atomic scale will bear influenceon many other fields of materials science.(c) Development of rational synthesis strategies forcatalystsUnderstanding of elementary steps in catalytic reactionsis only one prerequisite for a catalyst design. Even if oneknows exactly what the composition of a catalyst shouldFig. 2.9. Scanning tunneling microscopy during the reaction of CO andO 2 on Pt(111). The lines show the borders between oxygen and COdomains. Appr. 100 s between pictures (Fritz-Haber Institut).As in the other research fields, which are important in catalysisresearch, also the development of synthesis strategiesfor solids has far reaching implications in other fieldsof materials science. The solids properties, which need tobe adjusted during the solids synthesis, and thus controlledby nucleation and growth, are also important in the productionof pigments, building materials, and even the productionof pharmaceuticals.(d) Integration of heterogeneous, homogeneous and biocatalysisIndustrial catalysis is nowadays dominated by heterogeneouscatalysis. There are reasons for this, such as oftenbetter stability of solid catalysts and easier separation ofcatalyst and product. However, homogeneous catalysts aregenerally better understood on the atomic level, and heterogenizationof homogeneous catalysts could help to solve

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART86some of the problems typically associated with homogeneouscatalysis. In addition, homogeneous catalysts are muchsuperior in enantioselective conversions. This advantageis even more pronounced in biocatalysts, which areamongst the most active and selective catalysts known. Inaddition, they typically operate under very mild conditions,such as ambient pressure and only slightly elevated temperatures.Moreover, they can be very efficiently optimizedfor specific reactions by the novel techniques of directedevolution. First steps to overcome the barriers betweenthe different branches of catalysis have been taken, forexample, in mimicking enzyme active centres in the environmentof zeolites or by modelling enzymes with organometallicmodel complexes.A true holistic approach towards catalysis cannot maintainthe traditional separation between the three branchesof catalysis, which only very moderately overlap at present.Fundamentally, the mode of action of homogeneous,heterogeneous and biocatalysts should be identically. Onthe atomic level all kinds of catalysis are governed by thesame principles, and a true understanding of the nature ofcatalytic conversions will lead to a vanishing of the borderlinesbetween these subfields of catalysis.into projects including words with the prefixes “bio” or “-nano”. This has already led to a situation, where manyAmerican companies look towards Europe when they wantto hire catalysis specialists. Due to the limited number ofstudents entering universities to study sciences, the competitionfor qualified chemists, physicists and engineerswill become stronger, and even now European companiesare facing a severe shortage in well-trained scientists inthe field of catalysis. The situation with respect to Japanand East Asia is different, since in these countries increasedactivity in catalysis research can be identified.The leading position of Europe in this field needs to bemaintained and strengthened, since catalysis will remainto play a key role in the development of more economicaland environmentally benign processes. With respect tothe materials basis of our economy, Europe can only becompetitive, if better processes – which in the chemicaland related industries almost always means catalytic processes– are constantly being developed, since many of themature processes can be operated in developing countriesmore economically.Number12001000800600400EUU.S.2.5.6. Structure and Organization of European CatalysisResearchThe academic catalysis research in Europe is organized inmany countries in national virtual networks. The representinglearned societies in Europe have foundedEFCATS, the European Federation of Catalysis Societieswhich is an active body and which organizes the Europeancatalysis conference, having matured to a world-classevent.200Japan01995 1996 1997 1998 1999 2000 2001YearFig. 2.10. Number of publications in catalysis journals for the EU, U.S.and Japan.2.5.5. Position of Europe Compared to the U.S. and JapanCatalysis research in Europe is typically very strong comparedto the rest of the world (Fig. 2.10). In many fields ofcatalysis European companies and research groups areleading in the world, and this does not only hold for one ortwo European countries, but basically all over Europe. Thepresent trends seem to be a decreasing activity in catalysisresearch in U.S., since most of the funding is channeledThe industrial interest groups of producers and users ofcatalysis technology are also organized, in NICE, the Networkof Industries using Catalysis in Europe, an organizationcovering all major industrial players. Its currentactivities lie in the identification of needs and challengesfor research, done usually in specialized workshops complementingacademic conference topics.Both organizations are stable institutions, which could andshould play a role in organizing future European catalysisresearch. A close co-operation of both bodies can ensurethe direction of activities according to the needs of industry.Only then the technological achievements can bebrought to bear in European societies, as unlike in otherfields of technology, catalysis and the production of chemicalsand energy are characteristically large-scale technologieswith limited room for small industrial activities.

2.5.7. Preconditions for EC Actions in CatalysisFirst, it must be realized that the technology of catalysis isa fundamental and key technology to a wide range of industriesas all chemicals and most functional materials areproduced by catalysis.Second, it is important that from a thermodynamic pointof view the overall industrial efficiency in producing thedesired materials is about 50%. This gives an impressionof the potential for improvements of existing technologiesinto directions of ecological and sustainable production.The revolution in automotive technology which we may facewith hydrogen-based traction systems requires massive developmentsand quantum leaps in catalysis technology, bothon the sides of producing hydrogen-storage fuel systems(artificial petrol, methanol, ammonia) and in the on-boardtechnologies of fuel processing and electrocatalysis.2.5.8. Actions Suggested for the EC FrameworkWith these perspectives it seems essential to concentrateresearch efforts on the creation of a development platformand not to disperse the resources in the solution of specificproblems with strategies from the past.• Construction of a suite of methods allowing efficientlyto functionally characterize existing catalysts in order tocreate a secure knowledge base for novel developments.Large-scale facility access as well as creation of equipmentfor in situ functional analysis are pressing hardwarerequirements. Equally important is the broad integrationof theory and computer modelling into such aproject, which should be done on an “on-the-fly” basisand not in the way that theory explains previously obtainedexperimental findings. This new co-operationbetween theory and in situ experimentation is only possibledue to the enormous progress in both areas overthe last five years.• Development of methods for the rational synthesis ofsolids. Even if the requirements for a new catalyst areclear, it is nowadays not possible to devise a rational syntheticroute to create it. Concurrently with the activitiesin the other fields basic research into the understandingof the elementary processes during catalyst formation ismandatory to achieve full control over the properties ofthe final material.The most suitable framework for this platform is clearlythe creation of networks using the existing, but underequippedand uncoordinated research infrastructure inmany European countries. Significant investments inequipment are essential as well as the creation of a flexibleorganizational structure, which should be built on theexisting organizational infrastructure mentioned above(Fig. 2.11).MATERIALS: SCIENCE AND APPLICATION87The construction of an advanced technology platform forcatalyst development requires basic research with a perspectiveof about 10 years, consisting of three major components.Integration of the traditional fields of chemicalengineering, synthetic chemistry and physical engineeringis a further prerequisite for success in this field. The necessarycomponents are:• Evolution of high throughput technologies in their respectivefields (different for molecular and solid statecatalysis) into enabling technologies applicable by industryon a routine basis. To achieve this, a suite of instrumentationfor synthesis and testing of catalysts aswell as a suite of high throughput characterization toolsneeds to be created. Information technology and designtools for experiment strategies are essential ingredientsto such a technology, which require equal attention ashardware developments.2.5.9. Roles of Academia and IndustryThe chemical and application industries are the recipientsof all development efforts in catalysis. Industry should thushave a major influence in the evolution of the platform,which is designed to be used by them.A big obstacle in this endeavor is the secrecy consciousnessof chemical industry, which is extremely reluctant indisclosing or even undergoing any risk of giving insight intoany details of their production technology. For this reasonit is intrinsically problematic to bring industry into efficientco-operations close to production-related problems.In the past, frequently technologically less relevant projectswere pursued in co-operative activities, which wastedthus significant resources to protect the relevant informationfrom disclosure.It seems thus adequate to organize future networks in sucha way that industry takes the strategic lead but does onlycontribute to the operations in the framework of pre-competitiveactions pursued in their own laboratories. Industrialcompanies are essentially required as partners in futureframeworks but without the obligation to produce

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGARTHigh throughputcomponentsEFCATSIntegrated Methods forfunctional analysis andtheoretical descriptionNICENetworking environment for fundamental researchGeneric technology platformfor advanced catalysis researchMethods for rationalsynthesis of solidsFig. 2.11. Schematic representation of apossible research organization for the creationof an advanced technology platform.88commercially relevant results. The whole effort shouldremain pre-competitive and be directed towards the creationof technology, which is later used by industry outsidethe development networks. Success or failure of suchactivities may be measured by the documented technologytransfer and not by the difficult-to-assess direct commercialvalue of a particular development.2.6. Optical Properties of Materials:“Harnessing Light” 1 through Novel MaterialsP. Chavel | Laboratoire Charles Fabry de l’Institut d’Optique, Université Paris-Sud, 91403 Orsay Cedex, Paris, FranceContributors:G. Boulon (Laboratoire de Physico-Chimie des MatériauxLuminescents, CNRS and Université Claude Bernard,Lyon), A. Carenco (Opto+, France Telecom R&D, Marcoussis),G. Roosen (Laboratoire Charles Fabry de l’Institutd’Optique, CNRS, BP 147, F 91403 Orsay), J. Delaire (Laboratoirede Photophysique et Photochimie Supramoléculaireset Macromoléculaires, CNRS and Ecole NormaleSupérieure de Cachan), R. Lévy (Institut de Physico-Chimiedes Matériaux de Strasbourg, CNRS).2.6.1. Scope of Optical MaterialsOptics is defined as “the field of science and engineeringencompassing the physical phenomena and technologiesassociated with the generation, transmission, manipulation,detection, and utilization of light. It extends on bothsides of the visible part of the electromagnetic spectrum1) “Harnessing light ist the title of a recent report on the potential ofoptics by the U.S. National Research Council, 1998.as far as the same concepts apply.” The very definition ofall functions assigned to optics show that the progress ofoptical science and technology is closely determined byprogress in optical materials.Optical materials are developing rapidly in response to expectedimprovement in technological performance. Indeed,the sole field of optical telecommunications by itselfgenerates a high level of demand with tough requirementsto continue its progression along the optical version of“Moore’s law” under which the capacity of one single fibrehas been increasing by 33% every year since the mid 1970-ies. In addition, hardware for information science and technologyin general, as well as energy, environment, and consumerproducts, are further application areas for the developmentof novel optical materials. All classes ofmaterials, including in particular semiconductors, dielectriccrystals and organics are relevant. In this document,we review challenges faced by optical materials researchby the required function: light emission, nonlinear functionsin a broad sense including modulation and detection,or plain passive propagation and transmission.

In spite of outstanding existing skills in Europe and theU.S., Japan, in some case in association with pioneers ofthe field from the UK, has recently taken a lead in organicelectro-optics with some first commercial product. Also, aJapanese company has also introduced blue solid statelasers on the market. The U.S. have strong consortia onguided wave optics, infrared materials, vertical emittinglasers, and have been successful in pro-actively promotingmaterials technologies for future micro-electronics, e.g.involving X-ray imaging lithography. However, in a toughcompetition, European research is present on essentiallyall major topics, such as materials for telecommunicationsources, fibres and planar optics, organic materials, photorefractivecrystals, novel laser materials. EC funded consortiahave included optical materials but have not yet fullyexploited the possibility of giving an European dimensionto optical material research. Yet, national initiativeshave been successful and can be used to that end; to citebut a few, in France, “groupements de recherche” havebenefited research on laser materials, nonlinear opticalmaterials, photonic bandgap structures and microcavities;essential progress has been pioneered in the UK on photoniccrystal fibres, laser amplifiers, and in Germany on surfaceemitting lasers, among others.2.6.2. State of the Art(a) Light sourcesi) Laser diodes and light emitting diodes More than half ofthe multibillion market of compound semiconductors isdevoted to light sources. Present challenges include bandwidthextension, spatial and spectral control. In addition toefficient pumps for telecommunication fibre lasers used inlong haul transmission, telecommunication applicationsrequire wavelength control for dense wavelengths divisionmultiplexing with hundredths of independent channelsbeing carried in the telecommunication bandwidth, thatwould ideally need to be extended to 1.2 µm through1.65 µm with good temperature behaviour, extremely highspectral stability and accuracy, and high energy efficiency.Increasing the density of optical memories demands shorterwavelengths – blue diodes at 430 nm are expected onthe market very soon from Japanese sources but significantincrease in performance and further wavelength decreaseare still required. Combined blue, green and red light emittingdiodes or laser diodes may revolutionize lighting technologieswith significant energy savings arising from betterconversion of electrical to optical energy. Laser diodepumping of very high energy short pulses in the picosecondand femtosecond regimes are required for plasma research,with application to extreme ultraviolet and soft X-ray sources of industrial interest, e.g. for lithography.Most progress on laser diodes derives from innovative bandgap engineering and tighter fabrication control of heterostructuresemiconductors relying on molecular beam epitaxyor metal-organic chemical vapour deposition; industrialprocesses, though, would ideally benefit from improvedliquid phase epitaxy.ii) Solid state lasers, parametric oscillators Dielectriccrystal lasers, known as solid state lasers, complementdiode lasers by offering better spatial beam profile propertiesand a very broad spectral range from the mid ultra-violetto the mid-infrared needed for applications in informationtechnology, sensors, and environmental monitoring.They are expected to totally replace gas lasers and dyelasers in the coming few years, offering more reliable consumerfriendly operation in more compact units withequally good beam quality. When a good spectral match isavailable, diode laser pumping of solid state lasers offersthe most compact and energy efficient solution. Yet, theclassic titanium doped sapphire crystal, that offers uniqueperformance in ultrashort pulse generation, cannot yet beefficiently pumped by laser diodes. One competitive domainof research is therefore the identification of potentiallaser crystals for diode pumping and ultra short pulsegeneration, such as ytterbium ion doped materials thathave progressed significantly lately.The generation of controlled frequency beams throughnon-linear effects in a suitably pumped non-linear crystal,known as parametric oscillation, is one of the latest paradigmin coherent sources, offering the broadest range ofspectral tenability.iii) Fibre amplifiers and lasers The introduction of opticalfibre doping with rare earth for amplification and for fibrelasers was a vital change in telecommunication concepts.Improved gain control over a broader spectral range togetherwith dispersion engineering and non-linear propagationcontrol as well as application of these componentsoutside the communication area are now research challenges.High power carried by monomode fibres is requiredfor efficient Raman amplifiers.(b) Materials for nonlinear optics and light detectionIn a broad sense, nonlinear optics includes all effectswhereby an electromagnetic field affects the propagationof another electromagnetic fields. This usually occursthrough modulation by the control field of the refractiveindex “seen” by the probe field, thus affecting beam propagationphenomena such as convergence, diffraction, or absorption.The control field may be of any spectral domainfrom low frequency “electronic” signals to “optical” waves.For example, nonlinear optical effects have become domi-MATERIALS: SCIENCE AND APPLICATION89

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART90nant together with dispersion control in designing longhaul fibre transmission lines, and the optical control oflight pulses in telecommunication signals is of course vitalfor the challenge of all-optical switching. Storage materialsshowing such properties as nonlinear recording by secondharmonic generation, high index modulation recording,and 3D patterning are essential and urgently neededfor future mass storage technologies. A wide open gap isthe present lack of materials for short term, fast accessstorage devices and shift-registers.i) Semiconductors Heterostructures and in general bandgapengineering has been essential for the fast modulationand detection of light over an extended spectral bandwidth.Present challenges include the bandwidth extensionbeyond 40 Gbits/s per channel and direct microwavemodulation optical signals.ii) Organic compounds While unlimited engineering flexibilityand direct control of molecular orbitals for modulationbandwidths in the 100 Gbits/s range in polymers haveattracted interest for years, stability and process controlhave proved hard to achieve. Recent breakthrough onso-called “conjugated” polymers showing a gap for chargecarriers and luminescence upon recombination open clearhopes of popular commercial applications for large, relativelyinexpensive soft films used as light sources anddisplays. Low cost is also a major issue in end-user accessof optical communication (“fibre to the home”).Liquid crystals have been famous and successful for yearsfor display, but progress is still expected in large, brightdisplay applications as well as in relatively fast (submillisecond)control of large screens with potential applicationto motionless “spatial switching” fabrics.iii) Photorefractive materials So-called photorefractivematerials exhibit a noteworthy specific property: controllight beams induce an internal photoelectronic effects andphotocarriers are trapped in defect sites, creating a spacecharge field that in turn electro-optically modulates therefractive index. Photorefractive materials open newperspectives for the development of laser mode control inspace and time, and therefore higher beam quality andhigher brightness. Some photorefractive crystals have beensuccessfully inserted into industrial systems and can nowbe fabricated to suit application driven specifications, e.g.for vibration and deformation sensors. Further material optimizationis still needed for others, with potential applicationin such areas as environmental monitoring (Fig. 2.12).Again, a broader spectral bandwidth, together with temperaturestability, are major materials sciences challenges.iv) Artificial non linear materials and nanomaterials Abeautiful achievement during the recent years has beenthe control of efficient frequency doubling by anisotropymodulation along the propagation axis to secure phasematching between the illuminating and frequency doubledwaves. Such synthetic phase matching materials are(a) (b) (c)Doping controls conductivity and determines, among others,structures suitable as electrode materials. Organiclight sources have been extensively investigated in Europeanresearch laboratories but industrial applications seemto be somewhat lagging behind Japanese achievements.Excitation, orientation and relaxation mechanisms, synthesisof suitably pure chemical bases, stable dye graftingcompatible with the required nonlinear effects are stillwide open for research and emerging applications. Stabilityis mainly determined by purity, the influence of oxygenand photodegradation.Fig. 2.12. Restoration of a Gaussian laser beam (a) after degradationby a diffusing medium (b) such as a turbulent atmosphere, an inhomogeneousoptical material or even a strongly diffusing biological sample,can be achieved by four wave mixing in a non-linear “photorefractive”material (c).now being developed in thin films as well as in bulk dielectricand semiconductor materials. “Poling”, or electric fieldinduced anisotropy, confers new nonlinear properties tosome inexpensive materials as glasses.

Another form of artificial materials results from incorporatingnanocrystallites into suitable matrices. Such socallednanomaterials offer fundamentally new properties:quantum confinement, plasmons bands, 2D and 3D selforganization,enhanced scattering (resonant Raman scattering,fluorescence), and magnetic properties. Importantefforts have been devoted recently to size uniformity of thenanocrystallites incorporated in glasses, polymers, sol-gelsand others. Potential outcome includes ultra-fast and highnonlinearities opening the way to optical limiting, opticalstorage properties, and light probes for imaging, includingin biological applications.(c) Passive optical materialsi) Glasses Low temperature fabrication of glassy materialsusing the sol-gel process, as already mentioned for its potentialin nonlinear optics, has already significantly impactedthin film deposition processes for consumer applicationsand could affect bulk material fabrication if shrinkingand water ejection could be avoided. Superpolishingtechniques on glass has reached sub angstrom smoothnessdown to micrometre scales, and requirements forX- ray optics imply a further tenfold improvement.3D microstructures give rise to the so-called “photonicbandgap materials” (Fig. 2.13), that offer a very nice combinationof basic science research opportunities and verylarge application potential for the fabrication of highly integratedphotonic circuits, firstly in a planar guided wave configurationand in the longer term perhaps in 3D space.Full 3D control of optical propagation and nonlinearitiesis an ultimate challenge for research in optical materials,micro-optics and optical information technologies. Electronicink and diffuse displays are typical examples of stillwide open research that would clearly require both novelmaterials and nanometre scale patterning.MATERIALS: SCIENCE AND APPLICATION91Heavy oxide and chalcogenide and halide glasses are openingnew spectral windows in the mid and far infrared. Inexpensivemouldable infrared materials have scarcely startedto appear but would offer sizeable market opportunities.Fluoride glasses for low loss transmission in the mid-infraredwould be particularly valuable for application. Highpower laser beam transport requires specific glasses andfibre end coatings.Ophthalmic optics may still benefit from progress on organicand inorganic glasses: anti scratch, anti reflection,anti halo, rapid photochromic glasses are desired and requiremore work on material chemistry.ii) Mesoscopic patterning of optical materials Almostall optical materials are “synthetic” materials, as they requiresophisticated elaboration processes. “Artificial” materialsin addition combine mesoscopic structures smallerthan the optical wavelength that confers optical propertiesdifferent from the bulk and strongly dependent on detailedmicrostructure. The simplest case is thin film depositionfor reflection control, where loss control down to less thanone part in a million is still a challenge, for example for highaccuracy interferometry and for high power laser applications.Multilayers providing high reflection in the extremeultraviolet domain are a challenge for year 2008 nanolithographywith a significant impact on the microelectronicsmarket: Europe must remain in the competition and has allindustrial and academic partners required to do so. 2D andFig. 2.13. «Effective index» behaviour results from subwavelengthpatterning of transparent materials and offers some unprecedentedpossibilities for diffractive optics and micro-optical systems.2.6.3. Challenges and Expected Breakthroughs:Research PrioritiesHere we suggest some possible priorities that may be usedfor an European Materials Framework programme in relationwith the three categories of materials functions thatwere developed in the preceding section:• Sources: reduce the cost of high average power, highbeam quality sources (typical values: 10W average pow-

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGARTer and M2 factor below 1.5). Develop materials that willdeliver plug efficiency over 30% white light. Developsemiconductor lasers that will directly produce highpower, high beam quality. Develop all-fibre laser coveringthe whole spectral range of interest to telecommunications.Develop fibre lasers for mid-IR range environmentmonitoring.• Active materials: develop stable materials for 100 Gbits/smodulation and beyond. Develop self-luminous organicdisplays that can be developed into large matrices. Demonstrateactive materials improving vision through fogthrough phase conjugation. Demonstrate active patterningof electro-optic switches in a two-dimensional photonicbandgap material.• Passive materials: demonstrate less than .1 dB/cm lossesin a two-dimensional photonic bandgap material. Obtainrecord reflection factor over whole vacuum UV and extremeUV range for space and microlithography applications(120 down to 10 nm wavelength). Propose materialsolutions for reflecting multilayers below 10 nm. Developfibres for high power laser transport at all wavelengthsof interest to laser machining, welding and deposition.922.7. Magnetic MaterialsH. Kronmüller | Max-Planck-Institut für Metallforschung, 70569 Stuttgart, GermanyJ.M.D. Coey | Physics Department, Trinity College, Dublin 2, IrelandContributor:J. Buschow (Van der Waals-Zeeman Laboratorium, Universiteitvan Amsterdam, Amsterdam, The Netherlands).2.7.1. IntroductionNever before has our daily life and environment been sosignificantly dependent on materials with outstandingmagnetic properties. Modern life is today in many aspectsan automated world which uses ferro- and ferrimagneticmaterials in nearly all important technical fields as, e.g.,electrical power, mechanical power, high-power electromotors,miniature motors, computer technique, magnetichigh-density recording, telecommunication, navigation,aviation and space operations, automation micromechanics,medicine, sensor techniques, magnetocaloric refrigeration,materials testing and household applications.Recent developments in the field of exchange coupled thinfilm systems and the use of new techniques for the developmentof nanocrystalline (nc) magnetic materials haveinitiated numerous activities for the development of advancedmagnetic devices for energy transfer, for high-powerand miniature electro motors, for medical applicationsand for the sensor and magnetic recording industry, nowadaysknown as magnetoelectronics. Most of the progressachieved so far was due to the discovery of new materialswith extremely low (0.1 J/m 3 ) or extremely large magnetocrystallineanisotropy (10 7 J/m 3 ) as well as to the tailoringof high coercivities, H c , which are determined by the microstructureand vary between 0.1 A/m to several MA/m.Further progress in these fields is possible if we succeed todevelop materials with optimal property spectra where magnetic,electrical, mechanical, corrosive and thermal propertiesare optimized simultaneously. These advanced magneticmaterials also result in considerable energy savingsand in the case of magnetocaloric refrigerators, i.e., refrigerationwithout the use of chlorofluoro-carbons, the destructiveimpact on the ozone layer is avoided.2.7.2. State of the ArtHere only a brief review of advanced magnetic materialsused today will be given. These materials in general have ananocrystalline (nc) structure or, in the case of thin films,at least one dimension is in the nanometre scale.• High-permeability nc-materials based on Fe 3 Si with additivesof Cu, Nb, Zr, B (Finemet) achieve permeabilitiesup to 10 5 – 10 6 .• High-coercivity nc-magnets based on Nd 2 Fe 14 B andCoSm alloys with coercive fields of 1.5 T for NdFeB andup to 3.5 T for Sm 2 Co 17 -based magnets. Maximum en-

ergy products of technical magnets of 450 kJ/m 3 havebeen achieved. The development of composite materialshas started.• Giant-magnetostrictive nc-magnets with ≥ 10 -3 basedon (FeTbDy)-alloys for micromechanic applications.• Giant-magnetoresistive (GMR) thin film systems forread heads with magnetoresistances R/R > 50% andhigh permeability. Examples of multilayer systems areCoFe/Cu or Fe/Cr. Systems of GMR films are used todevelop nonvolatile “Magnetic Random Access Memories”(MRAM).• Colossal-magnetoresistive films of LaSr- and LaCa-Manganites with R/R > 100%.• Giant-magnetocaloric refrigerator material asGd 5 (Si 2 Ge 2 ) with T > 20 K effects.• Molecular magnets based on metal-organic compoundsbased on hexafluoroacetylacetonat or tetracyanomethylen.• Self-organized superlattices of ferromagnetic nanoparticlesof FePt or FeCo for high-density recording(Tbit/inch 2 ).• Computational solid state physics for the calculation ofintrinsic material properties and phase diagrams.• Computational micromagnetism of magnetic groundstates and the dynamics of magnetization processes innc materials, thin platelets and small particles.Future development of new multi-property materials thereforerequires interdisciplinary research activities, wherethe development of intrinsic properties as well as investigationsof the microstructure and of local chemical compositionsare carried out. The development of magnetic alloysis based on 27 elements of the periodic table leading to ~2100 binary and ternary ferromagnetic alloys from whichonly the binaries and a few ternaries have been investigated.Investigations on quaternaries or quinaries so far are restrictedto FeSi- and SmCo-based systems. Insofar a widefield of opportunities is still open for new research projects.In order to obtain high-remanence materials the dominanceof Fe is a pre-requisite. High-coercivity materials eitherhave to use rare earth metals in uniaxial crystals or transitionmetals as Co, Fe and Pt in strongly uniaxial crystals,e.g., CoPt, FePt. High-permeability materials require largespontaneous magnetization, vanishing magnetocrystallineanisotropy and vanishing magnetostriction. A furtherbreakthrough for these materials could be achieved if ncalloys with a larger spontaneous magnetization; however,still a low magnetostriction could be found. The presentlyused Fe 3 Si-based alloy, the so-called Finemet, has a spontaneousmagnetization of 1.25 T. The use of a FeZrB alloycould raise J s to a value of 1.5 T. Also the Curie temperaturewould be improved and could be further raised addingCo. The fine-shaded region in Fig. 2.14 shows thefuture possible improvement by using optimized nc-alloys.MATERIALS: SCIENCE AND APPLICATION932.7.3. Future VisionsMagnetic materials used presently in general are characterizedby one outstanding property as, e.g., high permeability,high coercivity or high remanence. For technicalapplication, however, it is a pre-requisite that a whole spectrumof properties has to be optimized. In so far the developmentof materials with optimal magnetic, electrical, mechanical,anticorrosive and thermal properties as well aslow hysteresis losses is one of the main topics in this field.Concerning the different types of materials outlined inSect.2.7.2 it is obvious that all of them are strongly dependentnot only on intrinsic material parameters as spontaneousmagnetization, J s , magnetocrystalline anisotropy, K 1 ,magnetostriction, s , and Curie temperature, T C , but alsoon the special types of microstructures. Actually the deviationsfrom the ideal lattice in many cases are responsible forcertain outstanding properties. In particular nanocrystallinemicrostructures and composite materials allow a widevariation of microstructures. Using suitable additives thegrain sizes as well as the magnetic properties and the chemicalcomposition of the grain boundaries can be tailored onthe atomic scale leading to the desired properties.Fig. 2.14. Upper and lower bounds for 0 and H c of soft magneticmaterials based on the fundamental relation 0·H c = M s B / L 3 (M s =spontaneous magnetization, B = domain wall width, L 3 = domain walldistance). Lower bound M s B / L 3 = 1 A/cm. Upper bound 100 A/cm.The fine-shaded region indicates a future upper bound for nanocrystallinematerials M s B / L 3 = 1000 A/cm.High-coercivity materials are based on the intermetalliccompounds Nd 2 Fe 14 B, SmCo 5 and Sm 2 Co 17 . Deficienciesof these compounds are the low Curie temperature of

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART94(BH) max[kJ/m 3 ]10009008007006005004003002001001Nd 2 Fe 14 B (T C = 312°C) and the low spontaneous magnetizationof SmCo 5 (1.05 T) and Sm 2 Co 17 (1.25 T). Thisallows applications only up to 100°C for the NdFeBsystems and the maximum energy products of the SmCosystems are a factor of 2 – 3 smaller than that of NdFeB.Fig. 2.15 presents the development of the so-called maximumenergy product (BH) max during the last century. Thisquantity is a measure of the energy stored by a magnet outsideits volume. The shaded region shows the progress,which could be achieved if a FeCo-based magnet with alarge spontaneous polarization of 2.45 Tesla could be realizedby introducing strong planar pinning centres.A breakthrough for the NdFeB type systems would beachieved for Curie temperatures of the order of 450°Cbecause of possible applications in the car industry. In anycase the use of NdFeB magnets for the electric energyproduction in wind mills will be a breakthrough concerningtheir efficiency and costs. Because of the smallervolumes of motors based on NdFeB magnets many newapplications have become relevant, e.g., elevator motorsor hybrid engines in car industry. However, higher Curietemperatures would even accelerate the acceptance ofthese magnets in the electro motor industry. In order toSteelAlnico(Nd,Pr) 2 Fe 14 BSm 2 Co 17SmCo 5hard ferriteFe 65 Co 35 + XSm 2 Fe 17 (N,C)19001950 2000 YearFig. 2.15. Progress in improving (BH) max over the last century. Theshaded region covers hypothetical FeCo-based alloys, which aremagnetically hardened by additives X.achieve this, far more additives have to be investigated inthe NdFeB systems.The production of nc-composite hard magnetic materialsas, e.g., Nd 2 Fe 14 B + -Fe or Pr 2 Fe 14 B + -Fe would improvethe situation of isotropic bonded magnets. Due tothe large magnetic moment of -Fe and the effect ofexchange coupling maximum energy products of (BH) max 100 kJ/m 3 could be achieved. These values are 40% largerthan the values of conventional bonded magnets. Inparticular the application of small-sized powerful electromotorsin audio and video devices as well as in computerperipherals results in an increasing demand of resin bondedRE magnets. The powders required for bonded magnetsare manufactured either by rapid solidification techniquesor by the so-called HDDR (Hydrogen DesorptionDecomposition Recombination) process. The melt-spintechnique produces isotropic magnets with large coercivefields with an enhanced remanence due to exchangecoupling between the nanograins. The HDDR techniqueallows the production of aligned sintered magnets withlarge remanence. It is decided by the costs and type ofapplication, which one of these techniques has to be used.For technical applications of giant-magnetostrictive materialsin micromechanical systems the Curie temperature(T C ~ 100°C) of the amorphous FeTbDy alloys (Terfenol)is a serious drawback. A breakthrough would be achievedif the amorphous alloy could be nanocrystallized, i.e.,achieving Curie temperatures of 320°C. The nc microstructureis a requirement in order to keep the coercivefield small and to obtain a large permeability. Multilayeredsystems of FeTbDy/Nb may fulfil these conditionsbecause the grain size is determined by the film thicknessand the Nb-layer does not dissolve in the FeTbDy-layer.High magnetostrictive permeabilities are obtained by softmagnetic interlayers. Because of the interplane diffusionduring nanocrystallization the magnetostrictive layer isdestroyed. It is on open question how to avoid this deterioratingeffect.The giant-magnetoresistance or GMR is a prominent exampleof modern magnetism. The GMR in multilayers isdue to the variation of the angle between the magnetizationof consecutive magnetic layers, which are separatedby a nonferromagnetic layer. Under certain conditions thecoupling between neighbouring layers is antiferromagneticproducing a large electrical resistivity, which decreasesdrastically if an external field aligns the magnetizationof all magnetic layers in parallel. The antiparallelalignment in zero magnetic field is a consequence of theinterlayer exchange coupling. The GMR effect also hasbeen observed in spin-valve structures, multilayered

nanowires and granular systems. The GMR effect is usedin devices such as sensors, read heads and nonvolatilemagnetic random access memories (MRAMS). The GMRresearch furthermore revealed a new class of magnetotransportphenomena obtained in nanostructures by employingthe spin polarization of carriers. Examples of thisfield of spin electronics include spin injection, spin dependenttunnelling and magneto-Coulomb blockade.Giant-magnetoresistive thin film systems require a high timestability and well-defined switching times for magnetizationprocesses. This can only be guaranteed by a reproduciblemicrostructure, e.g., well-defined interlayer boundaries.The existence of statistically distributed nucleationcentres at film boundaries or at edges leads to large spectraof coercive fields and a tremendous increase in noise ofmagnetic read signals. Accordingly, the production of perfecthighly homogeneous multilayer systems would be abreakthrough in this field. The GMR devices then may beused as nonvolatile MRAMS, marking the first successfuljoint venture of magnetic materials and silicon technology.A breakthrough in the colossal magnetoresistive (CMR)systems of manganites requires high-permeability materials,i.e., the so far available ceramic materials should be replacedby large grain or single crystalline materials in orderto reduce the coercive field down to the 1 mT range. Thismeans new preparation techniques have to be applied tomake these systems useful for magnetosensoric, spin-inducedtunnelling and pressure sensors. Here the tailoringof the microstructure is the dominant task to be solved.There are considerable fundamental and technologicalinterests concerning the electronic correlation effects inthe CMR systems. Double exchange, superexchange anddynamical Jahn-Teller distortions, charge and orbital orderinghave to be investigated. Furthermore, the applicationof manganite perovskite films in hybrid systems withsemiconductors where spin injection proceeds into thesemiconductor deserves further exploration.Molecular magnets suggest a wide field of applications innearly all technological fields reaching from conventionalelectrotechniques as microwave technique to medical applications,the sensor technology and the recording industry.A breakthrough is expected if the Curie temperature ofthese materials can be raised above 100°C. This may beachieved by coupling of the ferromagnetic molecules byanother intermolecular magnetic ion.Self-organized superlattices either produced by ferromagneticparticles or wires of FePt or CoPt or by a nanostructurizedsubstrate may be a future recording medium for theTerrabit/inch 2 recording density. A breakthrough is expectedif these superlattices can be produced perfectly in scalesof inches.2.7.4. Research Directions/Priorities During the NextDecadeFurther development of magnetic materials requires extendedstudies of phase diagrams of multicomponentsystems and the magnetic, electrical, structural and chemicalcharacterization of grain boundaries and intergranularphases. Future research activities should put the followingpriorities:1.Development of nc-magnets with large Curie temperatures,T C > 400°C, and large spontaneous magnetization,M s > 1.6 MA/m, for all kinds of applications (highpermeability,high-coercivity - giant magnetostrictivematerials). Energy products of ~ 1 MJ/m 3 for permanentmagnets and energy losses < 100 kW/m 3 for soft magneticmaterials at high frequencies of MHz.2.Differential analysis of phase diagrams and of the microstructureon atomic scales with respect to magneticproperties, constitution and chemical composition ofgrain boundaries. Combined application of several experimentaltechniques (EDX, EELS, TEM, AFM,STM) and of computational solid state physics.3.Characterization of magnetization processes in the nanometrerange by advanced magnetooptical techniques(magnetooptical Kerr effect, Circular dichroism, Lorentzmicroscopy) as well as atomic force and tunnellingmicroscopy.4.Developing materials for magnetocaloric refrigeration.5.Developing semiconducting magnetic materials for spintronixcombining the silicon technology with magnetism.6.Development of large-scale superlattices of self-organizedferromagnetic nanoparticles or nanowires in patternedsubstrates for high-density nonvolatile recordingin the range of Tbit/inch 2 .7.High-coercive thin film multilayers for high-densitymagnetic recording. Study of induced perpendicularanisotropy.8.Computational micromagnetism for the determinationof magnetic ground states and the dynamics of magnetizationprocesses in small particles and thin platelets.The efforts to achieve these goals should not be underestimated.Systematic, semi-automatic methods of combinatorialmaterials science are now being enlisted in the searchfor new ternary and quaternary phases. ComputationalMATERIALS: SCIENCE AND APPLICATION95

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART96electron theoretical methods have been developed to thepoint where intrinsic magnetic properties of new phasescan be predicted. At present magnetic moments of intermetalliccompounds can be estimated by means of the localdensity approximation and there is progress towardsaccurate estimates of the anisotropy energy and Curie temperature.The history of magnetic recording shows how adominant technology produces continuous improvementyear by year. Magnetic storage densities have been increasingat a rate of 60 - 100% per annum over the past 20 yearsand have now arrived at Gbit/cm 2 . The maximum energyproduct of permanent magnets doubled every twelve yearsthroughout the 20th century.Just recently the development of nanosized systems includingthin films and multilayered systems has led to newphenomena and novel applications. Further developmentsin these areas, combined with fundamental studies, willcontinue to have a strong impact on technology. It isevident that any materials breakthroughs are expected innano- and thin film technology. Further progress requiresconsiderable expertise and also a multidisciplinaryapproach. Naturally, there are clearly-understood physicallimits to future progress; the superparamagnetic limit insmall particles; the ultimate maximum energy product(BH) max is limited by the spontaneous magnetization offerromagnetic materials.2.7.5. U.S. – Japan – EU PositionsActivities on magnetic materials exist in all three countries.Also China and Korea have to be considered as strongcompetitors in magnetic materials. Singapore in future alsowill play some role. The handicap within the EU is thelack of an efficient recording industry. In so far the researchon recording materials and systems is somewhat isolated.The required interaction between industry and basic researchinstitutes cannot be initiated. In contrast theseinteractions exist in the U.S. and Japan being supportedby the National Science Foundation, the NASA, theNATO (dominated by U.S.) and the MITI, respectively.Recent cooperations between Infineon and IBM will notimprove the situation in the E.U. significantly because theBMBF may reduce the support for magnetoelectronics.high-quality soft and hard magnetic materials. Concerningthe research and development of new materials in U.S. aswell as in Japan there exist considerable efforts to developnew magnetic materials with optimized property-spectra.In U.S. as well as in Japan it becomes more and more usualto involve several institutions with supplementary knowhowfor the development of new materials. This has beenrecently demonstrated by NATO conferences entitled“Magnetic Storage Systems Beyond 2000” and “MagneticMaterials for Power Applications”.At different laboratories in EU exist the experimental andtheoretical background for the development of materialswith wide property spectra. In particular the basic knowledgeon fundamental physical, chemical and microstructuralproperties is available, i.e., the interdisciplinary collaborationcould be successfully performed between thedifferent departments.References1. R.C.O’Handley, Modern Magnetic Materials, Wiley, New York (1999).2. R.S.Skomski and J.M.D.Coey, Permanent Magnetism, IOP Bristol (1999).3. Lajos K. Varga, Int. Symp. on Soft Magnetic Materials (SMM 14), J.Magn. Magn. Mater. 215-216 (2000).4. H.Kaneko, M.Homma and M.Okada, Proc. 16th Int. Workshop on RareEarth Magnets and Their Application, The Japan Institute of Metals,Sendai (2000).5. H.Kronmüller, Magnetic Techniques for the Study of Microstructures ofCrystalline Solids. In: Proc. Int. Symp. on Relationships between Magneticand Structural Properties – Basis and Applications, (eds.) J.Echigoyaet al. (The Iron and Steel Institute of Japan, 2000) 3.The situation is much better in the field of sensor techniqueswhere the EU states have a worldwide leading position.Similarly in the fields of high-permeability and highcoercivemagnetic materials the EU is able to competewith U.S. and Japan. In particular the EU magnet industryhas to be considered as the leading one concerning the

2.8. Superconducting MaterialsR. Flükiger | Départment Physique de la Matière Condensée, Université Genève, 1211 Genève, SwitzerlandContributor:M. Marezio (Istituto MASPEC-CNR, Parma, Italy).2.8.1. IntroductionScience and technology of superconductors have stronglyprogressed in the last years, and the development hasreached an industrial level, for classical (metallic) as wellas for High Temperature Superconductors (HTS). Thecompounds Y(123) and Bi(2223) (see Table 2.2) have clearcommercial potential and are the focus of strong parallelacademic and industrial research efforts worldwide.CompoundYBa 2 Cu 3 O 7 Y(123) 93Bi 2 Sr 2 CaCu 2 O 8 Bi(2212) 92Bi 2 Sr 2 Ca 2 Cu 3 O 10 Bi(2223) 110TlBa 2 Ca 2 Cu 3 O 10 Tl(1223) 122HgBa 2 Ca 2 Cu 3 O 10 Hg(1223) 133Table 2.2. Promising HTS compounds.T c (K)Future superconductor applications include advancedpreparation and characterization technologies, down tothe nanometre scale. Possible use of HTS materials can besubdivided in two main areas:• Large scale energy-related applications (generation,transport, transformation and storage of electrical power),and• Small-scale electronics-related applications (passive andactive signal processing).Over the last years, large size demonstration prototypes(transformers, power cables, current limiters, magnets,etc.) have been fabricated and successfully tested. Applicationsas current leads for low temperature systems, magnetsand filters for mobile telephone base stations, havealready made it to the market. Solenoids for MRI applicationsare an upcoming future market.In many cases, the technical performance of superconductorapplications is already superior to that of classicaltechnologies, but production and material costs are stilltoo high for economic competitiveness. Strong efforts inmaterials research, both at the laboratory and at the industrialscale, have to be done, but the critical current densities,j c , in HTS compounds are inherently very high (>5 x10 6 A/cm 2 ), in order that these materials will become economical,either in a mean or a long term.2.8.2. State of the ArtSeveral projects related to HTS materials have been supportedwithin the 5th Frame Programme. The research2000/2001 in applied superconductivity covers four categories:(a) Basic research: mechanisms of superconductivityand new superconductorsBasic research in HTS has focused on three main topics:• The origin of superconductivity in these compounds.The actual mechanisms leading to superconductivityare still controversial. It has been predicted from opticalmeasurements of the energy gap that the maximumsuperconducting critical temperature (T c ) for cupratescontaining CuO 2 planes may be about 180 K. If thecauses for the actual limitation could be understood, T cof cuprates could be substantially increased. It is not excludedthat new material classes with high T c values willbe found, an example being the recently discovered compoundMgB 2 with T c = 39 K.• The processes limiting the current transport. While T cfor a given HTS compound does not much vary from onesample to another, the values of critical current density,j c , and irreversibility field, B irr , are extremely sensitive tochanges, depending on synthesis techniques. When optimizingj c at 77 K and appreciable magnetic fields, it isessential to introduce strong flux pinning centres dispersedin sufficient concentration. Chemical substitutionsin HTS have had positive effects on B irr (T) and j c .• The phase relations involved in the synthesis of theseceramic materials. Precise knowledge of these phasefields is indispensable if one wants to improve the superconductingproperties of HTS.(b) Energy applications: tapes and wiresSuperconducting energy applications such as power cables,transformers and fault current limiters, require the availabilityof thermally and mechanically stable, long conductors.The j c values of industrial Bi(2223) multifilamentary tapeswith a high degree of texturing are shown in Fig. 2.16, left.MATERIALS: SCIENCE AND APPLICATION97

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART98A second material class is now being considered as a serioussubstitute for Bi-based compounds: Y(123) coated conductors,where the biaxially textured superconductor is coatedon a flexible metal ribbon. These conductors exhibit excellentproperties, j c less affected by the presence ofappreciable magnetic fields, as shown in Fig. 2.16, right.The corresponding deposition techniques (see Sect.2.8.2.(d)) for long lengths (>100 m) are still under development,while conductor lengths of >2 m with j c values closeto 10 6 A/cm 2 have already been prepared. Future researchwill focus on cheaper deposition methods, which may varydepending on the envisaged particular application.Bulk melt-textured HTS materials allow novel applications,e.g. magnetic bearings and magnetic shields. Flywheelsdemonstrators have already been produced on a trial basis.Bulk superconducting materials for rotating machines withhigh current load require j c values as large as possible.Regardless of the chosen superconducting material, j c increaseswith higher crystal defect concentrations, obtainedby high temperature plastic deformation, nanoparticledoping, chemical doping or irradiation. Examples: InY(123), enhanced flux pinning has been obtained by rareearth (R.E.) substitutions on the Y site. The addition ofCa to Y(123) has shown to have a beneficial effect on thepinning at large angle grain boundaries. Both results havebeen obtained in European laboratories.Fig. 2.16. Overall critical current density of state-of-the-art conductors,Bi(2223) (left) and Y(123) (right), as a function of magnetic field andtemperature. The filled areas on the back-plane delineate the approximatefield and current requirements for various applications.(c) HTS electronicsPassive HTS devices such as filters with excellent qualityfactors have already made it to the marketplace. The outstandingchallenge for HTS is to develop a fabrication routethat will result in reliable and reproducible junctions foractive device applications such as rapid-single-flux-quantum(RSFQ) logic circuits or SQUID magnetometers.VLSI technology is already in use for low temperaturesuperconductor (LTS) (Nb/Al/O/Al/Nb) junctions, withoperational devices with > 10000 Josephson devices persingle chip already achieved. Most electronic and microwavedevice structures are based on thin films grown onappropriate substrates: LTS Nb-based technology is alreadywell developed, that of NbN slightly less. This is incontrast to HTS films, which need to be grown epitaxiallyon single crystal substrates; but their superconductingproperties are close to the intrinsic limit values.(d) Film deposition techniquesSeveral deposition techniques have been developed for fabricatingHTS films. For each HTS compound, the depositionroute has to be optimized individually for satisfying the prerequisitesfor commercial use of film-based applications. Itappears that only the full control of deposition techniques,allowing high j c values in layers considerably thicker than 1 µmwill lead to a larger success of superconductors. So far, allknown deposition techniques allow to reach j c values above5 x 10 5 A/cm 2 at 77K, 0T, for thickness still below 1 µm. Thereare various deposition techniques:Laser ablation and pulsed laser deposition, which are widelyused in research laboratories, are powerful tools for synthesisand preliminary investigations of new phases. The requiredsmall targets can be prepared in many laboratories,and stoichiometry is retained from the target to the film.This method can be applied for the fabrication of long tapes.Ion Beam Sputtering and Thermal Coevaporation (also onInclined Substrates) are particularly suited and cheap foruniform films over large areas. The former appears to bealso promising for scaling-up the film production. A Europeanteam has deposited YBCO films using coevaporationtechnique on substrates as large as 20x20cm 2 and reportedjc values of ≤ 2x10 6 A/cm 2 .Magnetron sputtering and Molecular Beam Epitaxy havebeen shown to produce high-quality films: these techniquesappear to be suited mainly for thin films and/or investigationof new hybrid structures, multilayers and devices.Special attention must be paid to growth by LiquidPhase Epitaxy.Chemical non-vacuum techniques: Very high j c values, >3x 10 6 A/cm 2 have been obtained on Y(123) layers by usingmetal organic deposition and MOCVD. Very recently, highj c values were also obtained for Spray Pyrolysis, a relativelysimple technique with high technical promise.A limitation is common to all these techniques: j c decreasesfor film thickness ≥ 1 µm, thus lowering the total criticalcurrent, I c , probably due to local stresses: Strongprogress is needed.

2.8.3. Future Research Visions and Expected BreakthroughsFuture R&D will aim towards higher j c values, improvedyield and lower material consumption, in order to bringthe manufacturing price down to a competitive level. However,further breakthroughs can only be achieved by meansof strongly increased effort in basic research in academiclaboratories.(a) Basic researchFuture basic materials research must contain a strong efforttowards the synthesis of some very high T c materials. Newsynthesis methods have to be found, replacing the actual laboratorymethods (e.g. high pressure synthesis, at > 5 GPa)by industrial techniques. Further efforts are also neededwith respect to current limiting mechanisms in HTS andpossible materials-related solutions. Although it is wellestablished that both grain boundaries and flux linedynamics are two important limiting factors, the materialsscience needed to tackle these issues on a nanometre scaleis still far from complete. Goals are:• Optimization of T c , j c , and H irr in HTS superconductingsystems exhibiting small anisotropy.• Reduction of toxic element content in Tl(1223) andHg(1223), by substitutions.• Further studies of the mechanisms in HTS materials,in view of higher T c in existing systems.(b) Energy applicationsi) Bi(2223) tapes Actually, industrial Bi(2223) tapes in kmlength can be produced, with j c values above 35 kA/cm 2 ,e.g. engineering je values > 20 kA/cm 2 . However, these valuesshould at least be doubled to be economical: a substantialchange of the industrial fabrication methods isneeded. Goals are:• Calculations and experiments on details of the hightemperature phase diagram.• New reaction paths for tapes with core density ≥ 80%and improved formation kinetics.• Fabrication of round Bi(2223) wires with high j c valuesand low losses in ac regimes.ii) Y(123) coated conductors Y(123) may be the superconductorfor the next decade, due to higher field tolerance,but also due to expected lower production costs withrespect to Bi(2223). The actual thin film material is excellent,but on small scale processes only. Goals are:• Coatings of thickness well above 1 µm without decreaseof j c .• Improvement of chemical (non-vacuum) depositiontechniques.• New characterization of deposition parameters forimproving the process reproducibility.• Scale-up of tape production to lengths > 100 m, e.g. forcables, magnets, energy storage, etc.• Scale-up of targets to diameters > 200 mm, e.g. forcurrent limiters, etc.• Further development of known alternative materialswith higher T c : Tl(1223), Hg(1223), etc.iii) Melt-textured bulk HTS The development of the processingtechniques for bulk HTS of complex shape andcomposite components and with very low resistivity is essential.The relevant properties for these materials are thecurrent densities, the magnetic fields, their distributions,the levitation force, the losses, and the mechanical andthermal properties. Goals are:• Processing techniques for complex shapes with very lowresistivity, e.g. flywheels, etc.(c) HTS electronicsLess expensive processing routes and cheaper bufferedsubstrates are needed, if a really broad mass market is tobe exploited. Many circuits will incorporate other materials,e.g. ferroelectrics, ferrites or colossal magnetoresistivematerials. Completely new technologies may have to bedeveloped to achieve the necessary reproducibility for HTSjunctions. This will require new material engineering forunderstanding the limiting factors for the performance ofjunctions and for providing the necessary characterizationtools. Europe should consider supporting one or more centralfoundries for the fabrication of thin films and devices,with a micron or less lithography. The first foundry couldbe devoted exclusively to the LTS materials. A programmeshould also be initiated in HTS thin films and junctionsfor any kinds of applications, including medical applications.Major collaborative programmes are needed for improvingunderstanding and performance of HTS films formicrowave applications and of junctions for SQUID andRSFQ applications. A major development programme isalso needed on large area thin film processing for fasterand less expensive film deposition, as a vital component offuture “wireless communication systems”. Note that thelast point is also valid for the coated conductors mentionedabove. Goals are:• Improvement of performance of thin films and substrates• Scale-up to large area processing and reduction of thecosts of thin films and substrates• R&D for reproducible multilayer technology for integratedjunction circuits and for dielectric substrates formicrowave films• Central foundries for the fabrication of LTS devices withlithography at submicron range.MATERIALS: SCIENCE AND APPLICATION99

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART1002.8.4. Comparison with U.S. and JapanA strong competition exists between the laboratories andindustries in the EU and those in U.S. and Japan. Eachregion has different centres of gravity, but that similartrends can be observed:• Bi(2223) tapes: Bi(2223) multifilamentary tapes areactually the only product being already on the market,in U.S. (market leader), EU and Japan. This conductoris still far from being optimized: new efforts have started,in several laboratories and industries of EU, and Japan.• Y(123) coated conductors: For certain applications,Y(123) coated conductors are superior to Bi(2223) tapes(higher field tolerance, expected lower productioncosts). In this field, European laboratories (in collaborationwith industries) have thus developed a strong activity,and their level is at least equivalent to that in U.S.and in Japan.• HTS electronics: The industrial engagement is muchhigher in U.S. and Japan, which explains that the volumeof this activity in the EU is somewhat smaller. However,this subject should be highly funded, also due tothe implication of miniaturized devices in promisingfuture applications, in telecommunication, but also inmedical applications.2.8.5. ConclusionsBreakthroughs in the field of superconductivity are intimatelyrelated to the progress in material research. Thefundamental aspect of material research, and in particularalso the search for new approaches, must be intensified inorder to maintain the contact with U.S. and Japan in thisfield. Developments in the field of applied superconductivityimply a great variety of material aspects, reachingfrom the study of bulk materials to the development of longconductors with filaments (or coatings) of sizes down to≤ 1 µm. The fabrication of devices (used in many fields,including medical applications) requires the technologyfor local material control at a scale of a few nanometres.1.2.3.4.ReferencesP. Grant, Superconductivity and Electric Power: Promises – Past, Presentand Future, IEEE Trans. Appl. Supercond. 7 (1997)112-145.A.I. Braginski, Application of high temperature SQUID magnetometersto nondestructive evaluation and geomagnetic exploration, Advances inSupercond. XI (1999) 9-24.M. Kotani, A clinical application of superconducting technology – themeasurement of magnetic fields produced by the human body, Advancesin Supercond. XI (1999) 25-30.R.H. Hammond, Review of coated conductor wire scale-up in the US,Adv. in Supercond. XI (1999) 43.2.9. Materials for FusionH. Bolt | Max-Planck-Institut für Plasmaphysik, 85740 Garching bei München, Germany2.9.1. IntroductionMaterials issues are of vital concern for the developmentof fusion energy into a sustainable source of energy supply.Advances in plasma physics and thus in fusion deviceperformance have been flanked by an increasing understandingof the environment to which materials areexposed in fusion devices and by the development andapplication of new materials. In Fig. 2.17 the progress ofthe plasma performance is shown as triple product of plasmadensity, plasma temperature and energy confinementtime. These data are related to the introduction of newmaterials for plasma facing applications. The Q=1 lineindicates the break-even condition at which fusion poweroutput equals the external power input into the plasma.Near-break-even conditions in present fusion devices(JET, JT-60U) have been reached with the help of surfaceand materials sciences. Now the emphasis is on powerproducingfusion systems and the related materialsresearch.In this respect, the next step in the world-wide fusion programme,ITER [1], Fig. 2.18, has to be the main aimallowing the calibration of operational requirements withmaterials performance in terms of chemical, thermophysicaland thermomechanical properties. At the same timematerials development for fusion has to be pursued aggressively.On one hand an intense neutron source has tobe built and operated to qualify base line materials for fusionreactor applications. On the other hand intense basicresearch into new materials is needed to offer fusionas an attractive and competitive energy system to society.

2.9.2. State of the Art of Materials Research for FusionTechnologyThe requirements and thus also the materials themselvesdepend strongly on the specific application in a fusion reactor,Fig. 2.18. Here, a distinction is made between “structuralmaterial”, “breeding material” (not being treated inthis article), “plasma facing material”, and other materialsfor special applications.(a) Structural materialsIn most exposed locations the structural materials of afusion reactor would be subjected to neutron-inducedatomic displacements of up to 30 dpa (displacements peratom) per operational year. This is accompanied by volumetricheat deposition and by the strongly material dependentbulk production of gas atoms (especially H, He).The baseline development covers ferritic-martensiticsteels with tailored elemental composition for reducedneutron activation. The latest development is the EUROFERalloy in which elements with high cross sections for activationby fusion neutrons have been substituted by more benignelements, e.g. Mo has been replaced by W; Nb by Taand V. The Cr content has been adjusted to optimize corrosionresistance and low embrittlement under neutron irradiation.The long standing research and development inthis field resulted in a material which is expected to withstandneutron fluxes up to 150 dpa and which allows anoperational temperature range of 300°C to 560°C. Thus astructural material would be at hand to build DEMO, apower-producing demonstration reactor after ITER [2].Exploratory work is being performed on dispersionstrengthenedsteels, which would allow for operation athigher temperatures.Materials, which are extremely attractive in terms of theirlow activation under neutron irradiation, are vanadium alloysand ceramic composites (SiC-SiC). Current knowledgehints that for these materials intense basic researchis needed to allow for the application in fusion.(b) Plasma-facing materialsOf the total fusion power in a reactor at least 20% will bedeposited on the surface of the plasma-facing components.The divertor surface will see local heat loads of the orderof 10 MW/m 2 . Transient heat loads in present devices canbe much higher, but intense research effort in plasma physicsis being invested into the development of control mechanismsagainst such operational transients.superconducting coilsvacuum vesselblanket divertorfirst wallMATERIALS: SCIENCE AND APPLICATION101ITER➚reactor condition10 2110 2010 19➚break even condition (Q=1)plasma facing materialsFig. 2.18. Main components and materials for ITER.structural materials10 1810 1710 1610 1510 1410 22 1960 1965 1970 1975 1980 1985 1990 1995 2000aust. steelNi base alloysWBeCFCgraphiteC, B, Si filmsComponents and materials for plasma-facing applicationshave seen very fast progress during the last years. The growingunderstanding of plasma-material interaction processeshas allowed the choice of applicable materials to be widenedand has resulted in the selection of Be for the first wall, carbonfibre reinforced carbon (C/C) composites and W for thedivertor of ITER [3]. Recent milestones in the field were10 131955Fig. 2.17. Progress of the fusion triple product of plasma density, temperatureand energy confinement time (nT) Q=1 means fusion poweroutput equals external energy input. The field “reactor condition”marks the operational field of fusion reactors. ITER is the internationalnext step in fusion development. The plasma facing materials appliedfor high heat flux components are indicated.• understanding of transport processes and materialsmigration in fusion devices (“erosion and redeposition”),• successful use of low Z composite materials and filmsduring the operation of near Q=1 plasmas,• development of dissimilar material bonds to removesteady state surface heat fluxes up to 30 MW/m 2 .

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART102In addition to these major activities in structural and plasmafacingmaterials advances were made with special materialsfor critical applications, e.g. the use of 10 cm diameter diamondwindows for 1 MW microwave power transmission.Finally, it has been shown that materials for the superconductingcoils are mature and ready for reactor grade application.Europe and Japan are presently leading the field of fusionmaterials science. U.S. efforts have severely suffered asfunding for fusion research has been cut, because the needfor a long term supply of sustainable energy is not beingregarded as a high priority within the U.S.Japan has a wealth of research activities in this field withmainstream development of fusion materials being carriedout by a national research institute (JAERI) and strong basicresearch in the field of radiation effects and materialstudies being carried out by universities. Subjects includelow activation steels, vanadium alloy development onindustrial scale, and pace making work on advancedSiC/SiC compositesIn Europe the member states of the EURATOMprogramme perform co-ordinated research in the fusionmaterials field with participation from mostly non-universityinstitutions. The materials programme, which is beingcarried out under the European Fusion DevelopmentAgreement (EFDA), mainly supports application-orientedresearch. Most of the effort is dedicated to low activationsteels, exploratory work being done on dispersion strengthenedsteel and other alloys as well as SiC/SiC composites.the local neutron flux density will be higher and thus allowaccelerated irradiation. The planning of this “InternationalFusion Materials Irradiation Facility”, IFMIF is beingcarried out internationally under an agreement of the InternationalEnergy Agency, IEA. Expected costs to be sharedinternationally are 600 M€ [2].In parallel to this evolutionary process of materials developmentand qualification, basic research in the field ofmaterials science is urgently needed. Here the aim is towardsa breakthrough in new materials with which fusioncan be offered to society as a highly attractive and competitiveenergy system. Regarding such new materials the mostimportant questions are:(a) To which performance can advanced low activationmaterials be developed?Directions are to increase the operation temperature foroptimum energy conversion efficiency and to further improvethe low activation properties of the materials. Possiblepaths are oxide dispersion strengthened steels, metalmatrix – ceramic fibre composites, SiC/SiC composites,and possibly vanadium base alloys [3-5], Fig. 2.19.Break through and success in this field would permit thehighly loaded components in a fusion reactor to be furnishedwith materials having high strength also at temperatureswell above 560°C (900°C in the case of SiC/SiC) and havinghighly favourable low activation properties. This wouldallow the thermal efficiency of a fusion power plant to beincreased well towards the 50% mark. The behaviour underneutron irradiation is critical with such complex advanced2.9.3. Expectations and Needs for the Next ten/twenty YearsexemptionSiC-metalSiC-SiC10 -5ITER will be the centre piece of the European fusion programme.Regarding materials issues, during operation ofITER the boundary conditions for the use of materials in areactor relevant environment will become preciselyknown. Plasma-material interaction processes should beunderstood and the heat flux removal technology shouldbecome mature.low act.steelbreak throughODSsteelrecyclinglowactivationpropertyafter 100y[Sv/h]10 -2The steady development of structural materials, especiallyof steels with low activation properties should result in aqualified material for building a first generation powerreactor. For this and for the testing and qualification of anyother fusion reactor material a 14 MeV neutron source isdefinitely needed. This facility will provide a neutron environmentvery similar to that in a fusion reactor, howevermed. active waste500 600 700 800 900 operatingtemperature [°C]Fig. 2.19. Aiming at a breakthrough in structural materials. High temperaturematerials, which can be easily recycled or exempted after reasonabletime, will underpin the attractiveness of fusion as an energy system.

materials and needs to be understood from the atomic scaleto the mechanical property level of the materials.(b) To which degree can thin films reduce the tritium uptakeof structural materials?The tritium uptake of the structural materials and the migrationinto the coolant should be reduced as far as possiblein a fusion reactor in order to minimize the tritiumquantity, which could be accidentally released.A further subject of intense research concerns the joiningtechnology of the plasma facing material to the heat sink,such that the high heat flux from the plasma can be removed.In order to proceed along this path, the following key technologiesare essential and have to be strengthened:• Advanced metallurgy (e.g. compositionally tailoredalloys; metal matrix composites) and joining technologies.• High temperature ceramic composite processing (e.g.SiC/SiC).• Thin film technology (e.g. permeation barrier coatings).MATERIALS: SCIENCE AND APPLICATIONPerspective for Fusion Materials ResearchToday New Facilities 2020 Goals103• tailored steels neutron source • radiation resistant Efficient fusion(IFMIF) low activation power productionmaterials withvery high temperaturecapability• tungsten, beryllium basic materials benefits for:technology science network • new functional • aerospacematerials for plasma• transportationfactoring and barrier• efficient energy systemsapplications• processing• ceramic matrix ITER technologiescomposites (CFCs)Fig. 2.20. Perspective of fusion materials research.The advances in atomic thin film deposition by plasma-assistedmethods and the possibility to tailor the nanostructureof these films during deposition open a new horizonin the development of permeation barrier coatings. Togetherwith an evolving understanding of the atomic interfaceand the migration physics, a new generation of tailoredbarrier materials could be developed.(c) Can plasma-facing materials with maximum lifetimebe developed?The use of high atomic number materials like tungstenwould possibly allow to drastically increase the lifetime ofthe plasma facing components. However, the interaction ofsuch materials with the plasma is extremely complex andneeds to be controlled. If research in this field would besuccessful, the lifetime issue of the plasma facing materialcould be resolved. Work on ITER will show whether suchplasma operation windows can be established, and perhapseven enable medium Z materials to be used. The thermalgradients in the plasma facing components, which areexposed to a surface heat flux of the order of 10 MW/m 2 ,will require advanced reinforced composite materials [6,7].It is obvious that these three fields also are closely relatedto other advanced materials applications and that theresults of this research will be highly valuable to othersectors, e.g. fuel cell and hydrogen technology (hydrogenpermeation barriers); aerospace and transport technology(composites); plasma technology (advanced materialsprocessing), Fig. 2.20.2.9.4. Actions ProposedA new initiative on basic materials science issues relatedto fusion is strongly needed and would be excellentlyplaced within a EC materials science programme. It woulddirectly enhance the performance of the EURATOMprogramme for the development of fusion energy.Important actions within the EC materials science programmeshould be:

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART104• New alloys and composite materials for high temperatureapplications.• Thin film processing - ceramic films with barrier functions.• Understanding and control of radiation effects incomplex materials.• Facilitating the construction and exploitation of anintense neutron irradiation facility (IFMIF).Integrating the competence of research laboratories (e.g.from fusion, aerospace, materials science), universitiesand industry into a “network of excellence” for the basicscience issues of fusion materials would be the mostappropriate step towards the aim of attractive and commerciallyviable fusion energy.References1. ITER Physics Basis Editors, F.W. Perkins et al., ITER Physics Basis, NuclearFusion 39 (1999) 2137-2638.2. T. Kondo, IFMIF, its Facility Concept and Technology, J. Nuclear Materials258-263 (1998) 47-55.3. K. Ehrlich, The Development of Structural Materials for Fusion Reactors,Phil. Trans. R. Soc. Lond. A 357 (1999) 595-623.4. R.J. Kurtz et al., Critical Issues and Current Status of Vanadium Alloysfor Fusion Energy Applications, J. Nucl. Mater. 283-287 (2000) 70-78.5. A. Hasegawa et al., Critical Issues and Current Status of SiC/SiC Compositesfor Fusion, J. Nucl. Mater. 283-287 (2000) 128-137.6. T.W. Clyne, P.J. Withers, An Introduction to Metal Matrix Composites,Cambridge University Press (1993).7.R. Leucht, H.J. Dudek, Properties of SiC Fibre Reinforced Titanium AlloysProcessed by Fibre Coating and Hot Isostatic Pressing, Mat. Sci. Eng.A188 (1994) 201-210.2.10. Materials for TransportationC.R. and W. E. Owens | UniStates Technology Corporation, LLC, Medford Massachusetts 02153-0101, United States2.10.1. IntroductionRising energy prices and heightened environmental concernsare intensifying the global push for quantum gainsin materials performance. In all major industries, there isan acceleration of the longstanding unfulfilled demandfor lighter, stronger, and more affordable materials. Thelack of a leap forward in materials performance continuesto be a brake to progress in many industries, but no industryis constrained more by the long absence of a breakthroughin materials performance than the transportationindustry.Other industries have been spurred by breakthroughs andare making rapid progress towards goals once consideredto be at the outer limits of their technological potential.For example, the Internet has revolutionized the telecommunicationsindustry, and the emerging map of the humangenome promises extraordinary progress in medicineand biotechnology. But, the materials industry has notachieved a comparable breakthrough. No outsized gainshave been made in materials engineering in the past 50years, and a revolution in transportation remains an apparition.As a consequence, the transportation industry is increasinglyreliant on composite materials. But, composites lackprecision in their makeup and sufficient predictability intheir performance, and their greater costs exceed theirmargins of performance versus traditional materials. Asan alternative, materials scientists have explored foamtechnologies. But, like composites, foams lack precisionand predictability, and the costly processes for producingfoams fail to realize a balance between density and porosity.Thus, the long-awaited breakthrough in material performanceremains elusive.SteelHigh strength steelAluminiumPlasticsCeramicsMagnesiumTitanium alloysAdvanced aluminium alloysNickel alloysSingle-crystal nickel-base alloysAluminium lithium alloysHigh temperature resinPolyimidesState-of-the-Art Materials in TransportationGlass-fibre reinforced polymersGraphite-fibre reinforcedpolymersPolymeric compositesMetal-matrix compositesPolymer-matrix compositesCeramic-matrix compositesStructural compositesIntermetallicsSuper alloysMicrotextured materialsSelf reinforcing liquid crystalsCarbon-reinforcedthermoplasticsLiquid crystalline thermosetsFig. 2.21. In an effort to make products lighter, stronger, and moreaffordable, the transportation industry is relying on a wide range ofincreasingly more complex, scarce, and expensive materials.

2.10.2. State of the Art of Materials Research in the TransportationIndustryTo achieve extraordinary advances, the transportation industryrequires materials that are lighter, stronger, safer,and more affordable than conventional materials (Fig.2.21). Engineers are pursuing these ideal parametersthrough increased precision in both design and manufactureto achieve greater uniformity and concomitant predictabilityin materials performance. For example, engineersare developing nanoscale and microscale materialsystems, using computational combinatorial methods todevelop new materials with novel properties, and integratingsensors and actuators into structures to make them “intelligent”[1,2]. Graded material concepts are being usedto improve material distribution in structures and, at theatomistic level, engineers are developing manufacturingsystems that use probes in atomic force microscopes to assembleatoms into precise molecular arrays of materials[3,4].But, a breakthrough remains remote. Conventional engineeringtechniques have not evolved to achieve sufficientprecision and uniformity to generate a dramatic increasein materials performance. The goal seems clear, however.A quantum gain can be achieved through a solution thataligns material mass with enough precision to optimizematerial distribution in a product. Historically, this hasbeen a recurring theme in materials engineering, whetherthe search has been for maximum density or maximumporosity in materials morphology. So, it seems that theelusive solution may be a structural technology that isbased on a calculus that balances the variation betweenthe two extremes.With such a technology in hand, materials research anddevelopment (R&D) could be brought into sharp focus,ending the wide-ranging and unresolved search of recentdecades. Near- and long-term R&D agendas could focuson the deployment of this technology to achieve the longawaitedbreakthrough in materials performance. Theseagendas could establish a clear strategy and direction formaterials R&D to drive a revolution in transportation thatwould reverberate through other industries and throughoutthe European economy. Technological history suggeststhat, given the overlong and relentless search forsuch a breakthrough technology, it must be on the horizon.Indeed, by virtually any standard, it is long overdue.2.10.3. Reflexive Material TechnologyThe most promising technology on the near horizon appearsto be Reflexive Materials Technology (RMT)[5]. This novel structural technology has the elementalunderpinnings and potential for ubiquity that distinguishesa breakthrough technology. RMT affords the design,engineering, and manufacture of optimal structures, becauseit minimizes the amount of materials required toform a product, while optimizing the structural integrityof the product. Unlike current technologies, RMT providesboth the design precision and fabrication control toproduce products made of the least amount of material(s)sufficient to assure reliable stress/strain managementaccording to performance specifications. With RMT, theideal parameters listed above finally can be realizedthrough a systems approach to materials development thatcombines structural solutions with materials & processsolutions (Fig. 2.22). Such an approach was recommendedfor cost-effective and competitive materials developmentby the transportation industry in a 1993 study conductedby the National Research Council’s Committeeon Materials for the 21st Century [6]. RMT provides thequantum leap in materials performance necessary toignite the long-awaited revolution in the transportationindustry.RMT engineering optimizes materials performance bycontrolling the manner by which structures are permittedto address load and, consequently, to undergo strain. It isparticularly advantageous for weight-limited applicationswhere a high strength-to-density ratio, high stiffness, andaffordability are important. RMT operates independentof scale and materials, with the same effect, whether atthe molecular (nano-) level or at the human-made (macro-)structural level. These characteristics provide anexcellent springboard for quantum gains in materialsperformance that could rival the impact of the Interneton the communications industry and the emerging mapof the human genome on medicine. The breakthrough inmaterials performance enabled by RMT could driveextraordinary advances in transportation and otherweight-sensitive industries.RMT achieves design precision and fabrication controlthrough distributed porosity. To strike the essential balancebetween density and porosity, RMT inculcates discrete,symmetrically aligned pores into structures madewith metals, polymers, ceramics, composites, and othermaterials. This is the RMT Architecture. The interplayof the symmetrically aligned pores, or voids, within anRMT-engineered structure, steers and spreads the stressMATERIALS: SCIENCE AND APPLICATION105

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGARTStructural SolutionsMaterials & ProcessSolutions106Fig. 2.22. Structural and materials & process solutions timelines.of external loading along the truss-like struts of the RMTArchitecture and throughout the structure. This stresssteeringminimizes the development of tensile strain in astructure in favor of maximizing compressive strain.The key to RMT stress/strain management is the spherelikegeometry of the Truncated Rhombic Dodecahedron(TRD), shown in Fig. 2.23. Figurative TRD cells shape anRMT structure, similar to the way soap bubbles shape afroth, or foam [7]. However, unlike the irregular distributionof bubbles in a froth, conjoined TRDs in RMT structuresare aligned symmetrically in a face-centred cubic(FCC) configuration that spontaneously creates a correspondingFCC array of voids in the structure. The void arraygives an RMT structure a framework, or skeleton, ofthe octa-tetra design. The struts of the RMT Architectureare triangulated and loaded axially and are short and fat tooptimize their capacity to carry compressive load. Thisunique architecture generates an isotropic material response,producing the optimal mechanical response byRMT-engineered structures independent of the loadingstate. Each RMT-engineered structure is optimized for aparticular application by a particular iteration of the RMTArchitecture.2.10.4. Computational Tool for RMT10 mFig. 2.23. Naturally occuring Truncated Rhombic Dodecahedron (TRD)in a mesoporous silica material [8] that might be the basis for selfassemblingand self-healing RMT-engineered materials.To simplify and speed the design, engineering, and manufactureof RMT-engineered materials, products, and structuresof uniform quality and performance, a new computationaltool is required. Development of this computer-based toolmust be a cornerstone of any near-term R&D agenda. The intentwould be for this practical tool to permit the precisiondesign, optimization, and manufacture of a vast number ofRMT-engineered products with optimum ease and efficiencythrough computer-integrated manufacturing (CIM). The goalwould be for this new enabling tool to allow engineers andothers to use high-performance computing to inaugurate a

new era in materials engineering and create a new generationof superior materials, products, and structures through RMT.The end-goal, of course, would be to afford the manufactureof commercial RMT-engineered products of uniform qualityand performance at competitive costs utilizing CIM techniques.Developed specifically for RMT commercialization,RMT rapid manufacturing systems readily lend themselvesto integration into CIM systems. RMT manufacturingsystems are now in the patent process. Fortunately, it appearsthat through simple modification of conventional manufacturingtechnologies, RMT rapid manufacturing systems can beincorporated into most existing manufacturing facilities withonly modest capital investments. Development of techniquesfor the rapid and cost-efficient integration of RMT manufacturingtechnologies into existing manufacturing plants andfacilities would be integral to a near-term R&D agenda.Near-term Materials R&D• Computational tool for RMT design, engineering, andmanufacturing.• Retooling of existing plant and facilities for optimal utilizationof RMT rapid manufacturing systems.• Re-engineering of existing products.• Optimal utilization of RMT rapid manufacturing systems toproduce re-engineered products.• RMT materials joining.• RMT materials repair and recycling.Fig. 2.24. Framed by RMT, industry priorities will dictate the agenda fornear-term materials R&D to produce lighter, stronger, and more affordableproducts.2.10.5. Near-Term Research & DevelopmentWhile RMT can frame the agenda for near-term materialsR&D, industry demands for lighter, stronger, safer, and moreaffordable materials must dictate near-term materials R&Dpriorities (Fig. 2.24). Thus, a prime near-term goal must beto re-engineer the architectures of existing products, components,and structures using RMT, to rapidly enhance thein-service performance of both intermediate and final productswhose designs are already proven through practical applicationand use. The results promise to be extraordinary,because RMT requires at least 5% to easily 50% less materialto make products and build structures that outperformtoday’s versions. Simultaneously, near-term R&D must focuson the proper selection and optimal utilization of RMTrapid manufacturing systems for cost-effective production ofRMT-engineered products and structures.To rapidly achieve quantum gains in materials performanceand ignite a revolution in transportation, near-term materialsR&D must enable the development of RMT-engineeredproducts and structures that yield significant economic,environmental, safety, and energy-related benefits.Near-term R&D must direct the efforts of transportationengineers, for example, toward exploitation of the advantagesof RMT to achieve the optimal balance between performanceand cost in existing vehicles, whether in the air,on the surface, or in the sea. Near-term utilization of RMTto re-engineer existing designs to create lighter, stronger,stiffer, and more affordable products would lead to:• Parts consolidation. This will mean fewer welds, easierassembly, faster production rates, reduced labor andcapital costs, and increased productivity.• Less framing. RMT engineering will allow substantialreductions in framing to support the ubiquitous platesused to assemble vehicles, e.g., airplanes, tanks, cars,trains, and submarines. Increased strength and stiffnessin RMT-engineered plates and panels will eliminatebowing or warping conventionally controlled by framing,lowering component and system costs.• Wider load distribution in vehicles will increase durability.Each RMT-engineered part, component, and subassembly(e.g., an instrument panel) automatically will beload bearing, up to its material limit. Spreading load andeliminating concentrations of strain will reduce materialrequirements and enhance vehicle safety, performance,and durability.• Materials substitution of less expensive materials in numerousapplications will generate wide-ranging economicbenefits, including direct and indirect cost savings.Improved fuel economy. Whatever the choice of materialsin a vehicle, RMT engineering will make themlighter, whether the materials are iron, steel, aluminium,plastics, magnesium, ceramic, or other materials.• Reduced environment impact. RMT-engineered savingsin materials and fuels alone could have dramatic environmentalbenefits worldwide, including substantiallyreduced vehicle emissions.• Increased safety and reliability. RMT-engineered improvementsin toughness, durability, and reliability ofparts and components will increase vehicle safety andconsumer confidence.• Increased passenger comfort by reducing interior noise,vibrations, and increasing handling and performancethrough sensor/actuators that track the environment andalign the structure to optimize performance.2.10.6. Long-Term Materials Research & DevelopmentLong-term, R&D drivers are primarily economic, not scientific.Therefore, long-term RMT R&D must focus on theMATERIALS: SCIENCE AND APPLICATION107

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART108development of new RMT-engineered products to satisfythe transportation industry’s commercial agenda (Fig.2.25). Historically, 95% of products that utilize a new technologyare yet-to-be-determined at the inception of atechnology’s use. Long-term materials research must beaimed at developing affordable new materials, with economicaland environmentally sound lifecycles (from rawmaterial to repair and recycling), that can be produced inlarge quantities using “green” engineering concepts [6].The focus must be to develop new materials that exploitthe structural advantages of RMT, which emphasizes thecompressive strengths of less expensive, less technical,and more abundant materials. New materials also shouldbe developed to exploit the precision of RMT rapid manufacturingtechnologies, which emphasize low-cost, automatedmanufacturing processes that are continuous fromraw material to finished product. Achieving long-termRMT materials R&D goals also must include continuedrefinement and development of computational tools tosupport a comprehensive concurrent RMT-engineeringapproach as part of evolving CIM technologies.Long-term Materials R&D• Develop new RMT-engineered products to satisfy thetransportation industry’s commercial agenda.• Develop affordable new RMT materials with economical andenvironmentally sound lifecycles that can be produced in largequantities.• Exploit structural advantages of RMT using less expensive, lesstechnical, and more abundant materials.• Develop new materials to exploit the precision of RMT lowcost,automated manufacturing processes that are continuousfrom raw material to finished product.• Continue refinement and development of computational tools tosupport a comprehensive concurrent RMT-engineeringapproach as part of evolving CIM technologies.• Develop educational programs to revive and replenish the ranksof materials and transportation engineers and scientists.Fig. 2.25. Long-term materials R&D must satisfy the transportationindustry’s business agenda by exploiting the unprecedented commercialadvantages of RMT.While RMT is the long sought engineering solution thatcan trigger quantum gains in materials performance, it alsois the solution for generating the verve and excitementthat will restore youth to an aging industry. Reflecting aglobal trend, over the past seven years in the U.S. aerospaceindustry the number of workers ages 25-34 declinedto only 17% of the workforce and the number of engineersand scientists performing R&D declined 30% between1998-1999. Europe has a rare opportunity to exploit thistrend to its competitive advantage by pioneering a technologicalbreakthrough that will attract the energy andcreativity of youth through open-ended opportunities forseminal innovations and the concomitant potential forextraordinary economic gains. To fully capture the advantagesof RMT, Europe’s long-term R&D agenda mustinclude educational programs to replenish and revitalizeits ranks of materials and transportation engineers andscientists.RMT precision and predictability open a new era ofconcurrent innovation, allowing existing products to beimproved and new products to be developed. To realizethe promise of RMT, industry and governments must workin concert. Industry must be the prime mover and governmentsacross Europe must provide critical R&D supportand new infrastructure. In particular, industry andgovernments must combine and focus their resourcesvia transnational and interregional cooperation to deploya new generation of RMT-engineered transportationsystems, including airplanes, ships, trains, and cars, alongwith the infrastructure to support these systems, includingRMT-engineered runways, roadways, railways,bridges, and piers. These new transportation systemscan be the foundation and impetus for an unprecedentedand extended era of broad-based economic growth andprosperity in the European community.References1. E.W. MacFarland and H.W. Weinberg, Approaches for rapid materialdiscovery using combinatorial methods, Materials Technology 13 (1998)107–115.2. J. Tani, T. Takagi, and J. Qiu, Intelligent material systems: applicationof functional materials, Applied Mechanics Reviews 51 (1998) 505-520.3. Y. Miyamoto, Applications of functionally graded materials in Japan,Materials Technology 11 (1996) 230–236.4. G. Wittenberg, Take one atom, Manufacturing Engineer 73 (1994)136–138.5. For a complete explanation of RMT in layman’s language and abstractsof RMT patents, please see the UniStates Website athttp://unistates.com/.6. Committee on Materials for the 21 st Century, Materials Research Agendafor the Automobile and Aircraft Industries, National MaterialsAdvisory Board, National Research Council, National Academy Press,Washington, DC (1993).7. C.R. Owens, W.E. Owens, and H.A. Bruck, Design and Fabrication ofOptimized Porous Structures Using Reflexive Material Technology,Proceedings of the 45th International SAMPE Symposium/Exhibition 45(2000) 1961–1971.8. Y. Skamoto, M. Kaneda, O. Terasaki, D.Y. Zhao, J.M. Kim, G. Stucky, H.J.Shin, and R. Ryoo, Direct Imaging of the Pores and Cages of ThreedimensionalMesoporous Materials, Nature 408 (2001) 449–453.

2.11. Materials Science in SpaceP.R. Sahm | Giesserei-Institut RWTH Aachen, 52072 Aachen, GermanyG. Zimmermann | ACCESS e.V., 52072 Aachen, Germany2.11.1. IntroductionMaterials science in space is a small but challenging sectorin the field of materials science. The environment ofreduced gravity existing in space puts fundamental researchin the field of materials processing within our reach.Under microgravity, the buoyancy convection in a melt issignificantly reduced and sedimentation effects are suppressed.This enables the investigation of crystallizationand solidification mechanisms with no interference fromconvective heat and mass transport in the liquid.In this way, the reduced gravity level existing in space providesan important tool for fundamental research projectsin materials science. Performing demanding experimentsin a microgravity environment can therefore be regardedas a revolutionary approach in materials science.fewer defects (Fig. 2.26). Directional dendritic solidificationunder conditions of purely diffusive heat andmass transport conditions in space show significantlyregular patterns consisting of larger dendrites in thespace experiments (Fig. 2.27).500 m1gMATERIALS: SCIENCE AND APPLICATION109500 mg2.11.2. State of the ArtMaterials science experiments have been carried out inspace for more than two decades. Solidification or crystallizationprocesses are sensitive to melt flow or sedimentationeffects. This implies that the experiments need at leastsome minutes of low gravity and therefore can only be carriedout during sounding rocket flights, during space shuttlemissions or at a space station. As a consequence, opportunitiesfor materials science in space are very few and farbetween. Each experiment needs years of intensive preparationand can be regarded as a ‘single shot’ experimentwith a high risk of failure. In this sense, the kind of ongoingexperimental programme, familiar in materials science onearth, does not exist for materials science in space.Nevertheless, previous microgravity experiments haveshown a series of important scientific results. In the followingsome relevant examples are mentioned:• In relation to microstructure formation during columnaralloy growth no comprehensive and systematic study existsand the data available is only limited. Using a binarytransparent alloy acting as a model substance for nonfacetingsolidification, earth experiments show deformedinterfaces and do not allow quantitative pattern evaluation.In contrast, the space growth sample shows anundisturbed and rather regular hexagonal pattern withFig. 2.26. Top view of a cellular solid-liquid interface in a transparent succinonitrile-0.075wt%acetonealloy, directionally solidified at a temperaturegradient of 2.2 K/mm and solidification velocity of 2.5 µm/s. The interfacestructure of the earth-grown sample (upper picture) is greatly interferedwith by convective buoyancy flow in the melt. The cellular morphology inthe space-grown sample (lower picture) is much more regular and allowsfundamental investigation into morphology evolution (ACCESS).1ggFig. 2.27. Cross-sections of directionally solidified Cu-29.5wt%Mn samplesat a temperature gradient of 2.75 K/mm and solidification velocity of5.8µm/s. The dendritic morphology of the space-grown sample (picturedright) is more regular and shows dendrites approx. 30% larger in size.These findings are attributed to the conditions of purely diffusive massand heat transfer in the melt in the microgravity environment (ACCESS).

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART110• First experiments in space in the field of equiaxed growthconfirm an environment free of sedimentation. The resultinggrain structure is much more regular than on earth(Fig. 2.28) and will provide a starting point for a betterunderstanding of grain growth mechanisms. Sedimentation-freesolidification is also important in the case ofperitectic systems which exist for many multicomponentalloys. Solid peritectic phases grow in the melt and behavelike in situ particles. The diffusive growth conditionsobtaining in space allow undisturbed observationof such technically important phenomena (Fig. 2.29).• The principal objective in relation to crystal growth ofsemiconductor materials is to study the origin of chemicalheterogeneities, both on the macroscopic and microscopiclevel. Space experiments using InSb anddoped Ge in Bridgman-type facilities show almost striation-freecrystals and therefore much better homogeneity.For crystal growth without contact to the wall thefloating-zone technique is used. Space experiments usingSi show that surface tension-driven Marangoni convectionalso impacts in a microgravitational environmentand restricts achievable homogeneity. On the otherhand, using compound semiconductors, such as GaAsor GaSb, crystals in sizes not attainable on earth havebeen processed.1gg• Containerless processing in space allows determinationof the thermophysical properties of the melt, e.g. viscosity,thermal conductivity, diffusivity, surface tension orenthalpy. In particular for glass-forming or highly reactivealloys, these space experiments provide unique datafor thermodynamic modelling.Fig. 2.28. Equiaxed solidification of refined Al-4wt%Cu alloys underalmost isothermal conditions. The space sample (pictured right) showsa homogeneous microstructure of dendritic crystals of nicely uniformgrain size. By contrast, ground samples show a much larger dispersionof grain size in the central part and an accumulation of very globularcrystals at the bottom as a result of sedimentation (courtesy D. Camel,M.D. Dupouy, CEA Grenoble).2.11.3. Expected Breakthroughs and Future VisionsFig. 2.29. The picture shows a cross-section of an Sn-13at%Sb sampledirectionally solidified in microgravity during the TEXUS-34 mission.The peritectic phase becomes directionally solidified from the left upto the marker (white lines outside), after which the sample isquenched. The pro-peritectic phase is dispersed over the wholesample because there are no sedimentation effects (ACCESS).Materials science in space is expected to make a crucialcontribution both to the fundamental understanding ofmaterials processes and in enhancing materials properties.Sophisticated experiments in a microgravity environmentallow crystal growth or alloy solidification under purelydiffusive heat and mass transport conditions. In addition,containerless sample processing available in space allowsthe measurement of properties of the melt such as viscosity,thermal conductivity, diffusivity or surface tension. Thisis why convection-free or containerless processing of this

kind provides a unique database for enhancing the accuracyof numerical models of microstructure formation.Fundamental investigations of this kind may result in theenhancement of industrial products. At present, there is arather large gap between simplified scientific experimentsand complex technical processes. To improve the transferof knowledge, closer interaction between science and industryis absolutely necessary. This means greater transparencyin scientific results for industry, as well as specificationof specific problems as an input for scientific researchusing microgravity.• In columnar growth, our understanding of the formationof non-planar solid-liquid interface patterns is nowherenear complete. In particular, understanding thestability and dynamics of dendritic or mushy interfacestructures, impacted by melt flow and freckle formations,is essentially important to most industrial castingprocesses. Benchmark experiments in microgravity allowmuch more ordered cellular or dendritic morphologiesas a basis for a better fundamental understanding.• Equiaxed growth often occurs in casting processes. Thedevelopment of equiaxed grains in the undercooled meltcan be studied extremely well through space experimentswithout superposed settlement of nuclei.In particular, lightweight metallic alloys, as applied in theautomotive industry, should be used for future well-definedbenchmark experiments. The results obtained in such experimentswill provide a database for numerical modellingand will be an aid in improving technical processes.MATERIALS: SCIENCE AND APPLICATIONTwo essential boundary conditions make the achievementof such a breakthrough within the next decade a realisticpossibility. Firstly, within the next few years the InternationalSpace Station ISS will be providing a platform forcarry out ongoing experiments in microgravity. Secondly,future activities in space will be joint experiments bygroups of scientists from different countries defining acommon scientific programme. Within the scope of thisMicrogravity Applications Promotion (MAP) programmeof ESA, industrial partners are directly involved in order todefine materials science research in space. In this sense,the concept of “learning for earth in space” can be realized.2.11.4. Research Potential and PrioritiesResearch potential for materials science in space can beidentified in areas in which buoyancy effects in the meltand sedimentation effects on earth play an important role.Space experiments allow a diffusive growth condition.Three main topics can be defined as follows:(a) Solidification of metallic alloysDuring directional solidification processes on earth, convectionin the melt significantly impacts the growth structureof the solid-liquid interface. In the case of metallicalloys, the main future goal is reliable determination offundamental relationships at microscopic scales. Thestrategy is based on a joint approach using well-definedspace experiments and theoretical and numerical modelling.Progress is mainly required in two topics:(b) Solidification of semiconductor materialsIn the case of semiconductor crystal growth in space themain objective is to understand the role of the basic transportmechanisms in the melt, i.e. buoyancy and Marangoniconvection. This is the prerequisite to producing largersizedcrystals with a greater degree of homogeneity andfewer defects than on earth. Key topics in the field of crystalgrowth may be wall-free growth from the melt (CdTeand compounds of Si and Ge), growth from the vapourphase (HgI 2 ), and research into chemical segregation inhighly concentrated alloys.(c) Determination of thermophysical propertiesMost technically relevant materials consist of more thantwo components. During solidification, a very broad rangeof different phases may occur, either enhancing or drasticallydeteriorating the properties of the materials. Understandingand predicting the structure of multi-componentalloys demands determination of thermophysical propertiesand knowledge as to how stable or metastable phasesare formed. Space experiments using a containerless processingtechnique may be able to measure relevant thermophysicaldata such as viscosity, thermal conductivity,diffusivity or surface tension in a highly accurate way. Thisdata is necessary input to enhancing numerical modellingof industrially relevant solidification processes.To sum up, in the above-mentioned topics, materials sciencein space is expected to be of great benefit in the future, bothby achieving better fundamental understanding of solidificationprocesses and by enhancing casting technologies.2.11.5. International SituationMaterials science in space in non-European countries ismainly concentrated in the U.S. and Russia, the two countriesmaintaining their own space facilities for research. Atthe same time, financial restrictions and the limited number111

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART112of flight opportunities, comparable to the situation inEurope, allow only a restricted number of space experiments.Russian scientists have been able to benefit from experimentson the space station MIR carried out over the last 15years. Facilities for crystal growth and solidification furnaceswere available. Unfortunately, published scientific resultsare very scarce and evaluation therefore very difficult.In the U.S., several groups of researchers are using a microgravityenvironment for materials science. An importantexample is the equiaxed growth of a thermal dendriteinto an undercooled melt. This sophisticated experimenthas allowed fundamental studies of diffusive crystal growthand provides excellent data for theoretical models. A secondexample deals with the interaction of particles at amoving solid-liquid interface. Mechanisms of particlepushing or engulfment are studied without the effect ofsedimentation of particles in the melt due to different specificdensities.To sum up, the boundary conditions for materials sciencein space throughout the world are comparable and there isno intensive and ongoing research. More so than in thepast, in the near future international scientific cooperationmust be established to work out a common definitionof the most relevant topics of research, and also to carryout series of experiments on the ISS, sharing the resultsbetween the various players. The Announcements ofOpportunity for Space Experiments on an internationallevel can be cited as an example.This will make materials science in space a concreteexample of international scientific cooperation. The mostrelevant topic for fundamental and application-orientedresearch will be defined by international groups of scientists.The experiments will be carried out, evaluated andpublished by international teams. Thus considered, theproject is part of the vision of a global world.ConclusionsIn this chapter a number of areas of materials applicationwere described in terms of specific examples. These applicationshelp our modern society function and will playan increasingly important role in the 21 st century. Severalscientists have declared this century to be the century ofbiology and biomaterials. Great advances have alreadybeen made in the field of biomaterials and biomimetics.However, this research has usually been carried out byengineers rather than by scientists. Consequently the materialsin use today have some desirable properties butthey were not developed specifically for biological applications.It was and still is difficult to understand the interactionbetween biomaterials and natural tissue. The solutionso far has been to cover conventional materials withhydroxyapatite, which has excellent mechanical propertiesand reduces the problems of toxicity. However, thelifetime of these biological materials is limited, rangingfrom 5 to 10 years. Second generation materials have tobe developed via close collaboration between mechanicalengineers, theoreticians (esp. computer modellers), materialsscientists, biologists, chemists, physicians, and surgeons.A strong link to the appropriate industry is, ofcourse, also required. However, there is the usual problemof commercial competition and barriers to the freeflow of information. It is important that fundamentalresearch into biomaterials receives a strong push similarto the way solid state science did some 40 years ago.An interdisciplinary approach to fundamental researchshould result in major breakthroughs in the generation ofnew biomaterial components. These components shouldbe able to replace human organs and body parts and havelow rejection rates and high durability. A similar challengeis to understand biology via a biomimetic approach. Theresults of these studies will be used to generate artificialmaterials that can be applied in different areas. It is wellestablished that biological cells are built from macromoleculesand supramolecular assemblies. Both the intracellulararchitecture and the interaction between cells arebased on soft and flexible nanostructures that are multifunctionaland highly intelligent materials. In addition,cells are able to build up hard materials such as shell andteeth and to control their morphology on the nanometrescale. Several challenges await research into biomimeticmaterials research, including understanding of the materialand transport properties of biological cells and tissues.

Furthermore, it should be possible to construct a modelsystem to which one can apply the experimental and theoreticalmethods of physics and chemistry. The results ofexperiments should be used to confirm or build on thismodel so that it can be used to develop better materials. Ifdetailed knowledge is obtained from the biomimetic approach,it can be used to develop new types of designedmaterials that are biocompatible and have well definedphysical, chemical and biological characteristics. Thesematerials could be used in bioengineering as well as inpharmacology and medicine. This objective again requiresa highly interdisciplinary approach.Materials are also critical to catalysis. To date, both homogeneousand heterogeneous catalysis have been basedprimarily on empirical knowledge, which is now reachingits limitations. Considerable effort is needed to replacethese empirical-based systems with a more theoreticallygrounded approach and start a de novo design of catalysis.This again requires strong links to be formed betweenphysical chemistry, inorganic chemistry and chemicalengineering.This is also true for materials used in nuclear fusion andtransportation. A diverse range of materials is used in boththese areas for a host of different functions, so that interdisciplinaryresearch is indispensable. For transportationit is also important that the economic and ecological aspectsare taken into consideration.Materials science in Space leads to an understanding ofthe influence of gravity on different aspects of materials,particularly their processing. This research is of both fundamentaland practical interest, especially if specific materialswith well-defined microstructures have to be synthesized.This type of research should lead to a betterunderstanding of specific processing conditions and phenomena.A major challenge will be the development of materialsthat fulfill not only one function (application) but also differentfunctions; so called multifunctional materials. Thecombination of different structural and functional propertiesin the one material will play an important role in thefuture, especially in the form of nanomaterials.MATERIALS: SCIENCE AND APPLICATION113Other materials with specific properties have to be developedby fundamental research (e.g., optical, magnetic,and superconducting materials). Impressive progress hasbeen made over the last decade, also within the 5 th FrameworkProgramme, and quite frequently on a phenomenologicallevel. More fundamental research has to be doneto overcome specific barriers. One example may be theoptical properties of fibres. There are enormous challengesfacing the development of new optical fibres with therequired complex array of properties. An optics equivalentof Moore’s law also exists which says that the capacityof one fibre increases by 33% every year. This law canonly continue to be obeyed if new materials and new processingroutes are developed.An often overlooked aspect of choosing materials for applications,especially new materials, is the need for widerdissemination of research results and properties to engineersand others in industry. Creation of databases, use ofthe Internet, and distribution of materials journals to awide audience all play a role in shortening the timebetween the discovery and application of a material.Similarly, magnetic and superconducting materialsresearch can only be furthered if metallurgists, physicists,chemists and engineers collaborate to understand the fundamentalfactors determining these materials’ properties.A comprehensive theory of superconductivity is still neededto understand why high T c superconductivity occursin cuprate ceramics. Nevertheless, it is well establishedthat for real materials the critical parameters of superconductivityare controlled by the microstructure of the material.A deeper understanding of the processes, however,would also be of great utility. Controlling the microstructureduring processing is essential.

CHAPTER 33. INNOVATION IN MATERIALSSCIENCE BY NEW INTER-DISCIPLINARY APPROACHES114115Y. Bréchet | ENSEEG/INO-Grenoble, 38401 Saint Martin d’Heres, FranceW. Pompe | Institut für Werkstoffwissenschaften, Technische Universität Dresden, 01062 Dresden, GermanyM. Van Rossum | Advanced Semiconductor Processing Division, IMEC, 3001 Louvain, BelgiumIntroductionMaterials science emerged as a independent interdisciplinaryscience in the 1950s. It encompasses traditionalfields such as metallurgy, ceramics, polymerscience, physics, solid state physics, and solid statechemistry. At first, materials science was conceived of asan intradisciplinary approach, where the different disciplinescollaborated for just a specific time on a specificproblem. However, the interaction between the traditionaldisciplines proved to be very fruitful and continued toincrease. Scientists from the different disciplines soonlearned that the concept of materials science as a wholerequired interaction with all the different fields. In thisway, materials science quickly turned into a very successfulfield in and of itself generating new materials essentialfor advancing energy, transportation, and informationtechnology.Materials science departments usually include differentgroups representing the base disciplines in science suchas chemistry, physics, physical chemistry, and engineering.The synergistic effects of the close interaction havebecome quite apparent. For example, many of the advancesin technology such as rapid information exchange, rapidtransportation, and fuel-efficient aircraft are a result ofstrong interdisciplinary interaction.In addition, huge progress in materials research has beenmade as listed in Table 3.1.Table 3.1.Successful Research in Materials Science• Metallurgical research• Microstructure and mechanical properties of metalscondensed matter physics and materials research• Quasiperiodic crystals – a revolution in crystallography• New and artificially structured electronic and magneticmaterials• Materials research in catalysis• The role of chemistry in materials science• Advanced ceramics• Organic polymers• Surface science• Materials synthesis and processing• Nanotechnology▲- and -phases in the high temperature alloy Nb-32%Al-8%Ti viewedin polarized light (U. Täffner, MPI für Metallforschung Stuttgart).

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART116Each of these areas represents a part of materials science.For this reason, the major part of this White Book on fundamentalresearch in materials science is devoted to theinterdisciplinary relationship of the so-called traditionalfields, i.e., those that cover the fundamental disciplinesof physics, physical chemistry, and engineering.However, it has become quite obvious that we need tobroaden our understanding of the field of materialssciences to also include other disciplines, such biology,medicine, information technology, and nanotechnology.Thus, the following sections provide a few examples wherethe field of materials sciences has successfully incorporatedaspects of biology, medicine, and quantum computing.In addition, several studies are available that considerthe expansion of the interdisciplinary field by addingmore disciplines (i.e., introducing intradisciplinary activitiesin the areas of polymer science, information technologyand nanoscience).

3.1. Present State of Materials ScienceIn the last fifty years materials science has been characterizedby a remarkable structural change. Materials sciencewas born in the scientific community of engineers, in themiddle of the last century. The success of solid state physicsand chemistry opened opportunities to build variousbridges between materials engineering and the naturalsciences. The penetration of the new thinking occurredwith different speeds in the various fields, for instance veryrapidly solid state physics and materials science wereinterconnected in the semiconductor research. A similarsuccessful interlinking was developed between materialsscience and polymer chemistry. In other fields such as thedevelopment of structural materials, the higher complexityof the dominating processes required the coverage ofall length scales from the microscopic via the mesoscopicto the macroscopic properties. It took much longer to implementbasic models discovered in physics or chemistry.For some applications new mathematical concepts had tobe worked out first, like the renormalization theory for thedescription of phase transitions, the J-integral concept infracture mechanics, the concept of fractal geometry forEngineeringMathematicsMaterials SciencePhysicsChemistryFig. 3.1. Materials science has been formed at the crossing point ofengineering sciences, physics, chemistry, and modern mathematics.the understanding of cluster growth and colloidal systems,or the solution of the non-linear moving boundary problemfor Laplacian growth processes to explain morphologicalphase transitions. Now at the end of the 20 th centurythis development is mainly successfully completed. Theadvanced materials science has been established as disciplineat the crossing point between engineering, physics,chemistry, and mathematics (Fig. 3.1). In this process specifictheoretical and experimental approaches have beencreated which depend on concepts of both, engineeringand natural sciences.INNOVATION IN MATERIALS SCIENCE BYNEW INTERDISCIPLINARY APPROACHES1173.2. Multidisciplinarity in Materials ScienceMaterials science is a crossover between various fundamentaldisciplines such as solid state physics, chemistry,mechanics, and process engineering. Recent developmentsin materials science and other related disciplineshave made multidisciplinarity a key issue.The need for a new approach will be obvious when we considerthe reduction of the scattering of properties – a challengefor the next decade, as far as structural materials areconcerned. Rather than improving the average property,which sometimes has reached its physical upper limit, it isessential to reduce the dispersion. Controlling the dispersionmeans understanding (i) the effect of process parameterson the variability of the microstructure, and (ii) thequantitative relation between these microstructures andthe resulting properties. Classical materials science aimsat answering to these two questions. In contrast, processengineering will proceed by statistical analysis, and willimprove through the use of Artificial Intelligence (AI) techniquessuch as fuzzy control, or neural networks. Understandingand controlling the dispersions in properties ofmaterials will certainly imply a close collaboration betweenthese two approaches, requiring a neural network partiallytrained on fundamental scaling laws of physical metallurgy.The development of such tools requires a close collaborationbetween materials scientists, process engineers, andapplied mathematicians.Over the past few years, a clear trend in structural materialsis the use of materials processing to evaluate and predict acomponent’s lifetime. Problems such as joining materials,casting defects and their influence on the lifetime of thematerials are key issues from an application-oriented pointof view. Those problems also require further scientificinvestigation from many specific angles: for instance, it isonly possible to study hot tearing in cast components or inwelds through a close collaboration between specialists inthermodynamics, solidification and micromechanics.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART118For new emerging fields it is crucial that the requiredresearch is approached in a multidisciplinary way. Thischapter briefly discusses the following three fields: (i)design of materials components, (ii) recycling of materialsand (iii) biomaterials science.The field of design, which means a selection of optimalmaterials and processing for industrial applications, hasseen a complete revolution in the last ten years with theoccurrence of new systematic methods to compare materialsand processes in an objective manner [1]. Thesemethods have proven their efficiency because it waspossible – with the availability of high-performance computers– to implement them in software programmes and tohandle huge amounts of data, structured in databases, formulticriteria selection. The evaluation of the costs of thedifferent processes was based on comparing them on thebasis of a microeconomics model. This booming field of«selection guides for design» is an impressive example ofmultidisciplinarity in materials science. The most recentdevelopments in this field cover the systematic investigationof all possible applications, and in the near futurethese developments might direct the development strategiesfor new materials. Such an approach is simply impossiblewithin a narrow separation of different scientificdomains.Recycling is becoming a crucial issue. The current overwhelmingimportance of ecological aspects in industrialand political decisions has important consequences on thedevelopment and selection criteria of materials. Solvingthis problem requires skills used in various fields, including(i) physical techniques to separate different qualitiesof wastes, (ii) investigations of the biological or chemicalmechanisms for their remediation, (iii) problems inducedby the recycling (Fe impurities in Al alloys, Cu embrittlementof steels etc.). Recycling is a source of interestingproblems for materials scientists, but the science of recyclinghas still to be created. This field would integrate thetechnical, economical and sociological needs in a systematicapproach.The educational system in Europe still relies on two paradigms:the classification of sciences by Auguste Comte,and the hierarchy course/tutorials/practicals in our pedagogicalpractices. The need for multidisciplinarity willforce an evolution of the educational system in these twoareas.Rather than trying to remove existing barriers between disciplines,we should consider an alternative approach: justnot building them. Project work should reacquaint studentswith the fact that scientific methods are universal,and the various sciences are not subordinate to each other,but all of them rely just on specific scientific methods.If we want the next generation of scientists to be able togenerate new fields in materials science and work on thesenew scientific challenges with innovative minds, we haveto train them in two ways: a technical approach to sciencewhich is the current methods, but also a cultural approachto science, which will develop their inquisitiveness.3.3. Obvious Needs for New IdeasOne of the most important contributions of physics andchemistry to materials science has been the microscopicunderstanding and design of new materials. Together withappropriate new analytical tools, such as high-resolutionelectron microscopy, synchrotron radiation, high-resolutionmass spectroscopy etc., and by new processing methodson the atomic scale (e.g. by scanning probe methods,lithographic methods, or the synthesis of supramolecularstructures etc.) this microscopic approach created a completelynew world of artificial materials with propertiescontrolled on the nanoscale [2-4].

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART1203.4.3. Understanding Materials Across the Length andTime ScalesAn important issue in materials science is how mechanicalproperties such as strength, hardness and toughnessscale with the characteristic size of a microstructure. Thisissue is especially important for materials problems inmicro- and nanotechnology. Computer modelling has becomean indispensable instrument for the advancement ofthe theoretical understanding of materials, particularly forsmall-scale materials and systems, where the magnetic,electronic or mechanical properties directly depend on theinternal (microstructure) and external (shape) structure.Particular attention has recently been directed towardsthe question whether and how the properties of a functionalsystem can be predicted on the basis of its knownFor example, new concepts of strain gradient plasticity leadto a linear scaling law between the square of indentationhardness and the inverse of the indentation depth. Amazingly,further experimental data show that such linear scalinglaw remains valid even down to nanometre lengthscales. As a second example, it is known that fracture energyvaries significantly with the thickness of metal layersin the layer structures of a microelectronic device. In thiscase, the scaling of fracture toughness with the characteristicdimension requires interface fracture modelling thatis separately from plastic deformation in a confined metallayer. In both cases, combined efforts in theory and experimentlead to a good understanding of small structures’mechanicalbehaviours. Future studies are required to studya variety of material and geometric lengths and their effectson mechanical properties in small systems.Sensor2mActuatorf 1 =68Hzf 2 =120HzFig. 3.2. Piezoelectric ceramics (PZT) with application as dampingcomponents in advanced cars or as substrates for new biosensors(surface acoustic wave sensor functionalized with a protein membrane)are examples for chances and challenges of materials developmentacross the scales.atomic or molecular composition (see Fig. 3.2). This dependson the understanding of how a particular crystal defector a particular molecule contributes to the collectivematerials properties and the function of the system. Thisis a challenging question, that requires the connection ofdifferent modelling schemes on significantly differentlength and time scales. Many fundamental aspects of sucha connection remain to be explored, particularly for theconnection between discrete (atomistic) and continuousmodels.3.4.4. Simulation of the Transition to Smaller ScalesExperimentation and simulation are equally important toadvance the understanding at this transition betweendifferent scales and different phenomena. In particular, insitu experiments geared towards testing modelling predictionswill be of greatest need. This need is generated (i)by the fact that the small-scale structures are usuallymetastable structures, far away from equilibrium wheretransient behaviour is of outstanding importance, (ii) themodelling of scale transitions usually involves multiplephenomena which cannot be separated and therefore haveto be compared directly to in situ observations.

Examples where the combination of in situ experimentationand simulation may be particularly fruitful includethe study of the deformation and the development ofcrystal defects in small volumes, their interaction withsurfaces and interfaces. In situ deformation in the transmissionelectron microscope or mechanical testing insidea scanning probe microscope will give basic informationon nucleation and interaction of crystal defects which arethe basis for the theoretical modelling of the mechanical3.5. Learning from “Mother Nature”properties, plasticity, fracture and fatigue of small scalematerials. Similarly, recent advances in micro-focus X-raydiffraction or in situ microscopy techniques enable materialssynthesis or deposition processes to be studied; thiswill allow validation of computer simulations of the microstructureformation, of nucleation and growth phenomena.Considerable research effort is, however, required to reachthese ambitious goals.INNOVATION IN MATERIALS SCIENCE BYNEW INTERDISCIPLINARY APPROACHES121At the same time we have learned from other fields that thegap is permanently growing between the materials we canartificially manufacture, and the materials we would like toproduce for use in our daily life. This is evidenced in thephysicians are now aware of living-tissue cellular interactionswith artificial materials, a trend which clearly calls for a paradigmshift with respect to artificially manufactured tissue.Thus the question of tissue engineering arises: will it be anFig. 3.3. Top-down and bottom-up approach in microelectronics to overcome the 30 nm barrier.incredible demands formulated in informatics for new materialsin order to guarantee the further increase of the storagedensity in microelectronics. Similar challenges have beenformulated for the materials science community by the lifesciences. For instance, whereas in the past it was possible tosatisfy the surgeons´ interest in new bone-replacement withhigh-performance structural materials (such as titaniumalloys, cobalt chromium superalloys, or alumina ceramics),a growing number of molecular biologists, biochemists andobject of future materials science, or is it too far away frommaterials science approaches?At this point it is necessary to ask “What could be the maindifference between an artificial and a biological material?”At least one difference is immediately obvious, when weconsider the building blocks of biological materials (suchas proteins, carbohydrates, lipids, or DNA) and materialstraditionally developed by engineers (such as metal alloys,

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART122ceramics, or polymers): the complexity of the living buildingblocks is significantly higher. The natural evolution overmillions of years led to selection of very “smart” molecularstructures which could be self-assembled to form the livingmatter. In other words “Mother Nature” uses highlysmart molecules to create her objects by relatively simpleand robust processing routes, whereas traditional materialsscience usually applies sophisticated processing routesto create artificial materials from simple elements. Thissituation will be transparent when we consider as an examplerecent developments in nanotechnology (Fig. 3.3).There are two complementary approaches: bottom-up andtop-down processing. In the first process single atoms ormolecules are manipulated to create new nanoscale components.In the second, lithographic techniques are usedto size down the structures to a smaller scale. The maindisadvantage of the first approach is the serial processing,whereas at least today the second strategy demands enormoustechnical efforts to achieve sizes smaller than 30 nm.Biomolecular structures open new possibilities. Biomoleculespossess dimensions typically from few to hundredsnanometres. That means, a single molecule could be usedas a template, compartment etc., for the synthesis of nanomaterials.Moreover, often biomolecules can self-assemble,thus parallel processing of higher ordered structure isa characteristic feature. We see the future of materialstechnology as the combination of two developments:• The convergence of top-down and bottom-up processingto overcome the 30 nm barrier.• The connection of traditional semiconductor materials(Si, SiO 2 etc.) with organic/biological materials, possiblywith ‘small scale structured’ interfaces.This path would open up plenty of new technological fields.3.6. Option for a New Interdisciplinary ApproachHAP-collagencompositeBiologicallyfunctionalizedsurfaceOsteocalcinMolecular biology is moving into the post-genomic age. Thegenomes of several organisms have already been completelysequenced. Thus molecular approaches can be developedfor the study of functions of cells, tissue, and organs.Growing understanding of the biological causality chainsTissue Engineering of Bone ImplantsRemodellingBone like mechanical andbiological behaviourArtificial bonesubstituteFig. 3.4. Future processing route of materials for bone replacement –in vitro remodelling of a scaffold of hydroxyapatite and collagen bybone cells.on a molecular level will open the door to revolutionarydevelopments in tissue and organ replacement (Fig. 3.4).This also applies to the use of biological processes fortechnical applications, particularly to the development ofbionanotechnology (see Fig. 3.5), and the future manufacturingof nanomachines modelled on cellular machines.In the last 20 years it has been demonstrated that materialsformed in nature have peculiar features [5]. The detailedstudy of biomineralization in different living organismshas shown that the smartness of the biomolecularstructures and the complexity of cellular processes createprocessing routes to make metastable crystalline phases,nanocrystalline inorganic- and organic composites, singlecrystals of highly complex shape etc.. The processes areoccurring in aqueous solution near room temperature,which means that they are sustainable per se. Increasingunderstanding of the mechanisms that control these processeshas been obtained. Although there are still manyopen questions, biomimetics is already an important focusof activity in the materials science community [6].Nature can also inspire materials research in the creationof optimized interfaces and surfaces. In a rather counterintuitiveway, finely structured sharkskin was found to

Metallization of selforganizing DNAtemplates with Pt or Pd clustersNanoelectronics using DNA templatesexhibit better hydrodynamic behaviour than perfectly polishedsurfaces. Similar surprises occurred in the searchfor non-wetting surfaces (“Lotus effect”). In the field ofmicrotribology, optimally structured surfaces were foundin insects that could guide the development of microstructuredreversible adhesive contacts. Overall, it is obviousthat the interaction between biological and materialsresearch will very likely produce exciting materials innovationsin the future.Fig. 3.5. DNA can be used as a template with unique self-assemblingbehaviour to grow nanoscale metallic wires by metalization fromaqueous metal complex solution.INNOVATION IN MATERIALS SCIENCE BYNEW INTERDISCIPLINARY APPROACHES1233.7. Molecular Bioengineering – a New Challenge for Materials ScientistsInitially developed with the goal of mimicking biologicalprocesses in a completely artificial way, biological elementsare now included as biomolecular templates and compartments,as well as living cells in biomimetic processing(Fig. 3.6). A promising sign is that European researchgroups (UK, Italy, Austria, and Germany) play an activerole in developing this field together with U.S., Japanese,and Israeli groups.Biological conceptGenomicsProteomicsTissue EngineeringMolecularBioengineeringBioinformaticsMaterialsScienceBionanotechnologyFig. 3.7. The major roots and implications of molecular bioengineering.Biomolecular templates,compartmentsBiomimeticsLivingcellsFig. 3.6. The main elements of biomimetics. It is a hopeful sign thatEuropean research groups (UK, Italy, Austria, and Germany) play anactive role in developing this field together with groups in the U.S.,Japan, and Israel.More generally, biomimetic materials processing is leadingto a new interdisciplinary forum which could be calledmolecular bioengineering. We see three major roots forthis new discipline: (i) molecular cell biology with contributionsfrom genomics and proteomics, (ii) materialsscience, and (iii) bioinformatics/biomodelling (Fig. 3.7).The fast developments of the genomic and proteomeanalyses open completely new possibilities for a directedintervention in cellular structures and processes. In thecreation of the new discipline “molecular bioengineering”,biophysical and biochemical methods have to be incorporatedinto the tool kit of materials science as shown in Fig.3.7. This development must be based on a significantbroadening of academic and educational programmes.Interdisciplinary teaching programmes were recentlydeveloped at leading U.S. universities. Such programmesshould be created at European universities too, with astrong background in materials science and biology. Tofoster this, particularly in the bioinformatics/biomodellingarea, the mathematical tools have to be created to deal withthe enormous data sets and to predict possible experimentalstrategies.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART3.8. Expectations for the Near FutureThe interaction of molecular biologists, materials scientists,and bioinformatics will create absolutely new waysfor materials processing. For instance already today molecularbiologists can “genetically” design new proteintemplates or microorganisms that show highly specificbinding behaviour to a given inorganic compound. “Neworganisms” can be created via a directed expression ofgenes, which code proteins that bind a specific inorganiccompound. In this way the horizon for future applicationof biomineralization and bionanotechnology will beexpanded considerably.1243.9. Actions that have to be Undertaken• The field of small-scale materials and structures is particularlypromising for creating scientific and technologicalbreakthroughs and innovations. Studies of sizeeffectson the behaviour of materials and the functionalityof systems are at present only in their infancy andwill require substantial research efforts. Furtherprogress in this area will critically depend on close collaborationsof materials scientists with physicists andmechanical engineers, on the one hand, and bioscientists,on the other. The EC should support focused researchand development programmes of cross-disciplinaryteams in this field.• The European materials science community should beallied with leading institutes in molecular cell biologyand bioinformatics, to establish joint European ResearchCentres in Molecular Bioengineering supportedby national and EC funds.• To strengthen the research expertise, and to increase thecompetitiveness with the U.S. and Japan in the next tenyears the EC should fund Mobility and Training Programmesin Molecular Bioengineering for PhD studentsand postdoctoral scientists.Moreover research platforms in important areas of materialsscience should be initiated. Possible themes include:• “Small-scale materials science and engineering”• “Bioengineering of bone and cartilage”• “Materials processing on biomolecular templates”• “Cellular machines and bioengineering”ConclusionsMaterials science is by definition an interdisciplinary field.So far, the field has been an amalgamation of fundamentalnatural sciences disciplines such as chemistry, physics, physicalchemistry, and engineering. However, recent demandsfrom industry as well as society require that new fields beadded, generating new areas of interdisciplinary research.Research in Europe should use its chance to join highlycompetent research teams from materials science, mechanicalengineering, physics, chemistry, biology and medicineto become a pace maker in the fast developing new multidisciplinaryresearch fields. Cross-disciplinary interactionshould be promoted by Research Networks, dedicatedresearch platforms as well as multidisciplinary mobility andtraining programmes for PhD students and postdoctoral scientists.The “Research Map” for multidisciplinary activitiesin materials science within the EU for the next ten years isproposed, see Fig 3.8.Chapter 3 particularly illustrates (although it is discussedthroughout this White Book) that “interdisciplinarity” is themost important aspect of materials science. It is importantnot to just collaborate but also to develop a common “language”and common thinking. Strong interactions have toexist between the collaborations. Continuous communicationbetween different scientist will result in fast advances.A workshop recently sponsored by the National ScienceFoundation and the Department of Energy on Interdisci-

Fig. 3.8. Research map for multidisciplinary activities in Europe.Cross-disciplinary Teams• Materials science• Physics, Chemistry• Mechanical engineeringEuropean Research Networks• Materials science• Molecular cell biology• Bioinformatics• Medicine• Computer networksMobility and Training Programmes• Materials science• Molecular cell biology• Bioinformatics• MedicineSmall scale materials and structuresSize effects on the behaviour of materials and the functionality of systemsInterface problems between materials processing and designDesign requirements, tailored materials, optimization of materials andprocess rules, selection rulesMolecular Bioengineering• New biomaterials• Tissue engineering• Bionanotechnology• Biosensors• BiomimicingMolecular BioengineeringTeaching and training ofPhD as well aspostdoctoral scientistsINNOVATION IN MATERIALS SCIENCE BYNEW INTERDISCIPLINARY APPROACHES125European Networks forMultidisciplinary Materials Research• Small-scale materials science and engineering• Bioengineering of bone and cartilage• Materials processing on biomolecular templates• Cellular machines and bioengineeringResearch infrastructure/policies• Creation of European Networks• Funding for young investigators in dedicated research platforms• Career development opportunities• Progressive academic reforms• Advocate flexible immigration lawsplinary Macromolecular Science and Engineering highlightedthe expansion of this interdisciplinarity by theaddition of the field of macromolecular science to the materialssciences arena. Large molecules can be consideredthe cornerstones of complex biological systems that wereformed by evolutionary processes that went on for millionof years. Techniques developed in physics and chemistrycan now find use in the macromolecular science andengineering disciplines, particularly with regard to suchbiological structures as genes and proteins.As we stand at the beginning of the new century, we can clearlysee that the knowledge that is rooted in disciplines such aspolymer science, chemistry, biology, and engineering is convergingto initiate a new interdisciplinary field-that of macromolecularsciences and engineering. The origin of this newfield is the narrow area of polymer science and engineering,which has grown over the past four decades around plasticstechnology. This new field could have a profound impact onsociety with respect to both economics and quality of life.Specifically, the field will have a strong influence on the pharmaceuticaland biomedical industries, manufacturing, infrastructure,and electronic information technology. Similarly,interdisciplinary macromolecular science will play a criticalrole in the development of nanotechnologies since the macromoleculeis the main object of structural diversity .We can also see that specific connections between biomaterialsand macromolecular biology could be very fruitful.The connection between cells and computer hardwarecould deliver new types of environmental sensors, medicaldiagnostic equipment, and probes of biological objectssuch as viruses and bacteria. Macromolecules hold the keyto such connections because cell receptors are essentiallypolymers embedded in the cell membranes. Novel structuresalso need to be discovered to generate contactsbetween synthetic and biological macromolecules.Recently, futurologists pointed out that the most importanttechnologies of the 21 st century-nanotechnology,robotics, and genetics-may generate a “machine” or an“animal” which may eventually make humans an endangeredspecies. Although it is true that some aspects of thisvision of interdisciplinary research may well be frighteningit is our belief that the benefits to humankind outweighthe risks. Like the discovery of nuclear fission, which ledto the atom bomb but also found numerous beneficialapplications, it is hoped that mankind will be intelligentenough to use the new technologies wisely.1.2.3.4.5.6.ReferencesM. Ashby, Materials Selection in Mechanical Design, Butterworth Heinemann(1999).A. Aviram, M. Ratner (eds.), Molecular Electronics, Science and Technology,Annals of the New York Academy of Science, New York (1998).R.W. Siegel, E. Hu and m.C. Roco (eds.), Nanostructure Science and Technology,Kluwer Academic Publishers, Boston (1999).A. ten Wolde (ed.), Nanotechnology, Towards a Molecular ConstructionKit, Study Centre for Technology Trends, Amsterdam (1999).H.Lowenstam, S. Weiner (Eds), On Biomineralization, Oxford UniversityPress, Oxford, (1989).S. Mann (Ed), Biomimetic Materials Chemistry, VCH Publishers, Inc. (1996).

CHAPTER 44. M ATERIALS THEORYAND MODELLINGT▲heoretical modelling of materials is an important andfundamental aspect of materials science that willbecome even more important in the future.Using the fundamental principles of physics and chemistrygoverning the states and properties of condensed matter,materials theory is devoted to modelling structural andfunctional properties of real materials quantitatively, andconsequently to designing and predicting novel materialsWhat models can be used?Classical MethodsSolid and fluids mechanics,FEM, diffusion theories,thermodynamics,statistical mechanics.Mesoscopic MethodsContinuum gradient theories,molecular dynamics,tight binding methods.Ab initio MethodsQuantum theory, DFT, …Materials ModellingWhat can be modelled?Materials:Metals, ceramics, polymers,biomaterials, nanostructures,macromolecular assembly, …Fig. 4.1. The scope and methods of materials modelling.Synthesis:Synthesis and processing, thinfilm growth, nanofabrication, biomimicking,self-organization, …Structures:Crystalline, amorphous,macromolecules, quantum dots…Properties:Moduli, hardness, tribologicalbehaviour, conductivity…Phenomena:Defects and failure, surface andgrain boundary diffusion, sizedependence and scaling laws,microstructure evolution, …Surface of a molten Si sample (optical micrograph obtained usinginterference contrast, G. Kiessler, MPI für Metallforschung Stuttgart).Introductionand devices with improved performance. The virtue andstrength of this theoretical approach is its “predictive power”.As one among numerous illustrative examples in theliterature, the recent theoretical prediction of superhardcarbon nitride (C 3 N 4 ) has motivated experimentalistsaround the world to synthesize this new material [A. Y. Liuand M. L. Cohen, Phys. Rev. B 41 (1990) 10727-10734;M. L. Cohen, Mater. Sci. Eng. A209 (1996) 1-4].Modern materials theory and modelling is characterisedby the following features (see Fig. 4.1. and 4.2.):• It is a scientific approach to technological problems:It aims to understand, control and design the structuraland functional properties of materials for industrial productswith specific purposes, lifetime and customer acceptability,distinct from theoretical studies of genericphenomena or classes of matter, as addressed traditionallyin basic science of condensed-matter physics andchemistry.• It is a quantitative approach with predictive power:It develops and employs mathematical and computationaltools for numerical and analytical calculations.These tools are accurate, quantitative and predictive aswell as robust and reliable.• It is cross-disciplinary and synergistic:It uses and combines various tools ranging from practicalmaterials engineering to fundamental condensed matterscience. It intimately connects theory to experiment forthe same material under investigation. It bridges lengthand time scales across many orders of magnitudes byjudicious selection of approximations: quantum mechanics,atomistic, continuum and statistical theories.126127

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART128What role has theory played in the past?ApplicationsDevelopment & improvementof new materialsOptoelectronicsComputersConceptMicroelectronicsNuclearAutomotiveCivilAerospace…CompositesSuperalloysClassical theoriesFEM,elasticity,plasticity,fracture,fluid mechanics,aerodynamics,dislocation theory,…Quantum theories,Electronic structure,device physicsand simulation,…Functional simulations;structure/microstructuredesign and optimization;Testing methods,fabrication methods,…SynthesisCharacterizationCeramicsInterface designPropertiesMaterialsDrug designFig. 4.2. Materials theory plays an indispensable role in the development and improvement of new materials in various industries.Consequently, materials theory and modelling is applicableto and beneficial for essentially all established as wellas newly emerging fields of interest in materials research(see Fig. 4.2.):– molecules, crystals, intrinsic structures and propertiesof condensed matter, surfaces and interfaces;– thermodynamic states and kinetic processes, chemicalreactions;– microscopic defects and nano-structured devices;– mesoscopic structures and biomaterials.In the following, capabilities and perspectives of this modernand active branch of materials science are illustrated with respectto three different points of view, based on the materialsscience of traditional solid state materials, soft matter, and nanoandbiomaterials. These aspects are discussed in the sections:4.1. Predictive Modelling of Materials4.2. From Basic Principles to Computer Aided Design4.3. Theory, Simulation and Design of AdvancedCeramics and Composites4.4. Modelling Strategies for Nano- and BiomaterialsContributors:Ch. Elsässer (Max-Planck-Institut für Metallforschung, Stuttgart,Germany), C.A.J. Fisher (Japan Fine Ceramics , Nagoya,Japan), A. Howe (Corus, Research Direction, Swindon, UK),M. Parrinello (Max-Planck-Institut für Festkörperforschung,Stuttgart, Germany), M. Scheffler (Fritz-Haber-Institut derMax-Planck-Gesellschaft, Berlin, Germany), H. Gao (Max-Planck-Institut für Metallforschung, Stuttgart, Germany).

4.1. Predictive Modelling of MaterialsM. Stoneham | University College London, London WC1E 6BT, United Kingdom4.1.1. What is meant by “Materials” and by “Modelling”?Materials modelling includes familiar tools which are alreadypart of engineering practice. These include finiteelement (FE) and finite difference (FD), computationalfluid dynamics (CFD), and free-energy minimisationprogrammes. These can all be usefully extended and improved.But Predictive Materials Modelling goes much further.State-of-the-art electronic structure calculations canlead to cements with the right setting times, or to the bestchoices of piezoelectric transducers. Atomistic studiescan identify the right catalyst system, or the behaviour ofnuclear fuels under extreme conditions. The quantitativeunderstanding of structure at the mesoscale and how thesestructures are created can improve polymers, the textureof ice cream and thermal barrier coatings. One active field,established commercially, uses quantitative thermodynamic,kinetic and statistical modelling to produce alloyswith enhanced performance, e.g., improved recyclability,or materials optimised for gas turbines.Predictive materials modelling is not new, of course. Pioneeringwork by Mott in the 1930s was followed by thefirst general-purpose codes for the semiconductor andatomic energy industries in the 1950s and 1960s. Changesin the last few years have been dramatic. This promptedthe UK Foresight Programme to review the field, andespecially what should be done. This present paper bringstogether some of what was learnt from that exercise, whichwas based on an e-mail questionnaire, open meetings, andextensive individual discussions.There are very diverse views as to what “materials modelling”actually is or is not. It is not theoretical solid statephysics, except as a source of methods and their validation.Apart from excluding approaches like CAD (computer-aideddesign), FE (finite element) methods, or CFD(computational fluid dynamics), we adopted the empiricalworking definition “materials modelling is that which isdone by those who regard themselves materials modellers”.“Modelling” includes computer-based approacheswith very varied strategies, not excluding analytical methods.Its role depends greatly on the industry involved. Indrug design the molecule (perhaps hydrated) is most of thestory, and there is a large amount of “Research” relative to“Development”. Modelling in a “guided choice” approach,pre-selecting favoured new molecules, leads to large economiesand, to a fair degree, discoveries generate the market.Yet there is a limit: no one could licence a drug whichwas only computer designed. In aerospace there is plentyof “Development” and less “Research”, since for aerospacethe big issues are more about integrating many technologies,and less about exploiting some single discovery oradvance. The chemical industries will often use CFD andother tools based on mass action and thermodynamic data.The semiconductor industry defines modelling challengesin the Semiconductor Roadmap (SIA1994), ranging fromstrain-layer phenomena, to solid state processes underelectronic excitation and with high concentration gradients.This industry’s band-structure codes were amongthe first general-purpose codes for materials modelling.Materials science differs from condensed matter scienceand solid state physics because of its crucial technologicaldrivers. These include (a) Fitness for some purpose (perhapsan intrinsic property such as a modulus, an adhesionenergy for unlike solids such as metal and glass, perhaps acapability for optically-induced change, such as writingBragg gratings in optical fibres or photographic materials);(b) Whole life behaviour (such as the modelling of nuclearfuel evolution in use, high temperature creep, the breakdownof silicon oxide under electrical stress, polymer degradationafter disposal); (c) Customer acceptability, so theproduct can be made and sold (e.g., factors such as colour;using the phase diagram to ensure a processing route whichkeeps price and quality acceptable; food texture, polymerdesign to ensure appearance matches performance); (d)Economic, safety and environmental aspects (e.g., optimizingmaterials for radioactive waste disposal; identifyinguses of new high-tech materials which, though of high cost,nevertheless lead to overall economies, like the “carbonceramic” forms of diamond). Materials performance is aproper aim of materials modelling. The traditional solidstate science of ground state structure and energy are onlya small component.Technological needs vary enormously and unpredictably. Anumber of industries (e.g., the food industry, or the defenceindustries) include projects over much of this wide range ofmodelling. The variety takes several forms: (a) Types ofmaterial: Metals and metal alloys; Ceramics and glasses;Semiconductors (including multilayer and nanopatternedsystems); Polymers and polymer-based composites; Othersoft solids (liquid crystals; colloidal matter; ice cream); (b)MATERIALS THEORY AND MODELLING129

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART130Which property? Magnetic (including magneto-optic, magnetoresistive);Electrical (insulator/dielectric, semiconductor,conductor, superconductor, electron emission); Optical(passive, active, like photochromics); Thermal (conduction,barrier, heat-insensitivity); Mechanical (Young’smodulus, yield strength, toughness); Special (performanceas a gas sensor; laser performance, catalyst); (c) Whichlength scale? From the clearly atomic, via the mesoscopic(typically, a few nanometres to microns) to the macroscopic,with these scales sometimes extensively mixed; (d)Which timescale? From femtoseconds to geological timescales.Many important systems are either prepared or usedwhen neither in thermodynamic equilibrium, nor homogeneous.It is not good enough to model just an equilibriumphase for materials most readily prepared far from equilibrium,like diamond films. Modelling the means to obtain amaterial can be very important, especially in high value materials(diamond, photonic or microelectronic materials).4.1.2. Types of ModellingMaterials modelling ranges from simple visualization tostate-of-the-art “accurate” methods. There is no such thingas a universal “best” method: in the most effective modelling,the degree of sophistication is right for its task. Sowhat are the aims of materials modelling? Views variedwidely, and did not support some earlier views that predictingthe crystal structure of the most stable form of somematerial was the most significant objective. Simple properties,like bulk modulus, attracted only modest interest.The ideas most favoured by industry related to the improvementof existing materials, the direction of novel materialstowards a critical need in the marketplace, the close involvementwith engineers and experimental scientists, andthe identification of routes which one should not take.(a) Modelling as a framework of understandingUnderstanding of what might be important can come froman analytical idealization, possibly using a computer forspecific cases or for some parameterization. The reaction/diffusionmodel of silicon oxidation is an example.Property maps bring together simple analytical models andexperimental data to help in the pre-selection of materialsaccording to figures of merit. Simple calculations have themajor advantage of making the big ideas clear, paving theway for more sophisticated work.One should not underestimate this level of approach. Gettingthe right understanding can mean better engineeringsolutions. For semiconductor materials, understanding ofperformance-limiting defects proved of far more value thansubsequent detailed defect models. It enabled routes tobe found to avoid critical defects (e.g., Si in the 1960s,when dislocations were the problem, or in the 1970s, whenswirl defects caused difficulties, etc). One of the majorcontributions of modelling (at whatever level) is to help toavoid obstacles or bad routes forward.(b) Scoping: The next stabScoping calculations are designed to decide which termsreally matter, by making the minimal (but perhaps sophisticated)prediction of key energies and the like. Such methodsare common for defect energies, for basic comparisonsof different phases, or for separating out contributions ofprocesses occurring at the same time. They can be used forlooking at trends in the relationship between performanceand molecular structure. They may be used to put boundson behaviour on very long time scales. One would not wishto take a novel component into production using only materialsproperty values from scoping calculations, yet onemight well feel happy about using scoping to eliminate somepotential materials, or not to follow up some idea.There are many approaches, from simple scoping to highlysophisticated methods. Some of the best simpler methodshave an excellent track record of prediction. One suchclass is based on interatomic potentials, especially forionic systems (e.g., fast ion conductors, nuclear fuels likeUO 2 , catalysts like zeolites), where the shell model hasproved a very accurate and flexible approach. Another classincludes semi-empirical quantum chemical methods, likeCNDO (Complete Neglect of Differential Overlap) andits successors, and also including the newer Tight-Bindingapproaches.(c)”Accurate” calculationsUse the best quantum mechanics you can afford. We mustdefine our vocabulary, since there are common, but inconsistent,uses. Accuracy relates to agreement with reality,and is not the same as precision, which relates mainly tothe numerical precision and reproducibility of a computation.“First principles” and “a priori” are terms which areconfusingly used, only appropriate for approaches at leastas basic as Quantum Monte Carlo methods. We shall usethe descriptor “state-of-the-art methods” for the widelyusedDensity Functional (DFT) and Hartree-Fock (HF)approaches. Sometimes, these are “parameter-free” whenthey do not involve empirical information. In practice,there are simplified versions, such as the Local DensityApproximation (LDA). These may adopt hidden empiricalelements, e.g., by choosing to include or omit gradient corrections.The semi-empirical quantum chemical methodsare usually systematic simplifications of DFT or HF theory.Most include self-consistency (in the same sense as HF

theory); some approaches use local charge neutrality,which is more approximate.Implementations of these methods make significant workingapproximations, whether as assumptions in pseudopotentials,or in basis set. The system may not have atomicpositions relaxed to equilibrium. Is a small cluster used, oris a small supercell used? If so, what is done about polarisationdue to charged species: is the cluster embeddedproperly? Experienced workers know about these difficulties.As scientists, they usually know how to get their modelsright. But this is not good enough, for state-of-the-artapproaches to be used seriously in an industrial setting. Inan industrial setting, those involved want to be able to trustthe results they generate. If different pseudopotentials givedifferent results, or if including or not including someterms like gradient corrections makes a qualitative difference,the results may have no useful value. They may noteven suffice to identify routes not to take. “Robust reliability”is an important issue.Accuracy (how well the predictions match the real world)is another issue. A calculation is reliably accurate, if youcould trust it without any experimental input (would youfly in an aircraft whose materials were designed solely usingsuch calculated values?). Significant cases exist wherethe current “state of the art” is simply not accurate (e.g.,O in Si). Of course, there are valuable applications of stateof-the-artmethods which are less ambitious. We foundthat most examples using state-of-the-art methods in thematerials area (as opposed to condensed matter physics)did so to interpret spectra in materials analytical methods.Often, state-of-the art modelling implicitly assumes onlyground states in equilibrium matter. However, industrialchallenges are far wider. Some metastable systems havemajor practical value (e.g., steels). There are substantialopportunities for materials modification by exploitingexcited states and, as already noted, in both these cases,kinetic issues become important.4.1.3. Targets for State-of-the-Art Materials ModellingSoftware for state-of-the-art modelling is widely available.There is a wide range of experience in its use, mostly butnot entirely in the university sector. What are the targets?(a) Target: moleculesMolecular structure codes are widely used, often in thecontext of drug design (which is not part of our study). Furthercodes are available to predict many properties of molecules,including electrical, optical, and vibrational properties.Despite many formidable successes, there are continuingreports of cases where straightforward predictionsfail, e.g., giving incorrect molecular configurations. Insome cases, this may be because there are different stateswith very close energies, or because electron correlationhas to be handled at a sophisticated level. Whatever thereason, it is an obstacle to routine use of codes in an industrialenvironment.(b) Target: crystal structuresAs for molecules, there are some significant successes.Some of the successes are more for trends across a seriesof systems, rather than for absolute predictions, but thatcan be nearly as useful. A recent Benchmarking Exercisefor organic crystal structures showed promise, but made itclear that there can often be different structures of verysimilar enthalpy. This raises again the point that metastablestructures can be very long-lived (“A diamond is forever”,it is said). Which structure a system actually adoptscan be determined by kinetics, rather than energetics, forexample, and modelling needs the capability to handleboth classes of structure.(c) Target: intrinsic materials propertiesThese might include vibrational properties, elastic constants,optical absorption spectra, and phase changes.They may include band gaps, band widths, electron affinitiesand carrier effective masses. Surface propertiesinclude surface reconstructions, surface energies and surfacestresses. There is much activity in these areas, somevery successful. Accurate prediction of bandgaps continuesto be challenging; accurate predictions of energiesinvolving changes in electron numbers (like work function)are still more difficult.Steels are among the cases where solid state kinetics andmetastable phases are of value. It is not yet possible to usestate-of-the-art methods to design, say, creep-resistantsteels, although simplified molecular orbital calculationshave been attempted. The right problems have still to bedefined, and might involve predictions for carbides andintermetallic compounds common in heat-resistant steels.Yet valuable insights and some quantitative guidance forreducing long-term embrittlement in multicomponentsystems have been achieved.(d) Target: thermodynamics and thermophysicalapproachesState-of-the-art methods are targeting these topics,although it will take time for their impact to be large. Nooneexpressed the view that state-of-the-art calculationswould replace the current, partly empirical, free energyMATERIALS THEORY AND MODELLING131

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART132approaches in the short (or perhaps even the medium)term, except perhaps for special cases.(e) Target: local solid state properties and energiesThere has been a major effort to model intrinsic defects inmaterials, partly driven by nuclear reactor programmes.For metals, there are successful calculations of propertiesof simple defects. These include models based on interatomicforces, which might be used in molecular dynamics,as well as state-of-the-art calculations which can predictthermodynamic properties. There are significant gapsin treating cascades, for which there are extreme conditionswhich may involve excited electrons. For semiconductors,there have been successful models at various levels.Effective mass theory continues to work with remarkableaccuracy, even outside its natural range of validity. Yetthere are significant gaps, especially in understanding diffusionunder realistic conditions for modern processing,such as rapid thermal processing. Again, there is much tobe done to understand fully the role of different chargestates and of excited electronic states. For ionic solids,interatomic potential methods based on the shell modelhave been very successful for certain classes of problems.Some properties, like surface energies, can probably bepredicted more accurately than they can be measured. Absolutediffusion rates have been calculated with accuracy.For ionic solids, the excited states have received muchmore attention, partly because of clear roles in photographyand other special systems. However, there are difficultieswith the highly non-stoichiometric systems, wherethere are both combinatorial and energetic problems. Theelectron-lattice coupling can change dramatically fromone system to another, with small polaron behaviour (inwhich carriers hop incoherently, rather than propagate asin silicon) important in understanding materials rangingfrom X-ray phosphors, nuclear fuels, and colossal magnetoresistanceoxides. Clearly, materials modelling has to describean enormous variety of behaviour, significantly morevaried than for, say, drug design. This is both a strength anda weakness. The strength is the aboundance of opportunitiesand challenges. The weakness is the range of toolsand experience needed to take up that opportunity.(f) Target: mesostructuresApproaches tend to be system-specific, albeit with a smallnumber of recognisable categories (e.g., whether an averagemedium approach is acceptable, or whether many statistically-similarrealisations must be treated). There is disagreementin the field as to whether all length scales needto be treated in a single code (the “spanning the lengthscales” issue). How different timescales can be combinedis an analogous problem, especially in systems where thereis history-dependence. For example, in modelling laser ablation,there is energy absorption late in a laser pulse byfree carriers excited at earlier stages. The successful examples,on the whole, did not involve multiple length scales.Successful examples of mesoscopic modelling range widely.They varied from modelling plasma-sprayed thermalbarrier coatings, through laser ablation, microelectronicinterconnects, organic light emitting diodes, and nuclearfuel modelling, to the texture of ice cream.4.1.4. Technology Transfer and Other LinkagesTechnology transfer raises a range of issues. The linksbetween the science base and the software industry arevery good at their best, but extremely variable. On thewhole, there is poor follow-up from academic code to acommercially useful code (usually meaning a well-packagedPC-based code). Unless industry’s own modellingteams give a lead, there could be a temptation to concentrateon yesterday’s industries, not those of tomorrow.The links between software houses and industrial users arealso very variable. This is partly, at least, because of thelimitations of the small, short-lived modelling groups inindustry. Small- and Medium-sized Enterprises (SMEs) inparticular lack ready sources of impartial advice. Materialsmodelling is itself a wealth-generating industry. It is a relativelynew industry, firmly based in information technology.Its customers expect from it both the right technical contentand the full range of the latest IT options. For softwarehouses, expectations of advanced graphics have been important,since the software skills and effort to produce theright graphical images are still relatively uncommon andrelatively expensive. Likewise, the effort needed to maintaina code has grown to far more than a spare-time activityof the research scientist who created the first version.Those with modelling skills are likely to be highly sought inindustries both within and outside the materials area. Oncetrained, students with a Master’s degree in materials modellingare expected to be very versatile. They will surely be indemand from the materials industry. There is some concernthat they will also be in demand from other areas such as IT.The current fashion is to suggest networking as a cure forall problems of linkage. Networks can be useful, but canbe very time-demanding. The existence of a networkshould not hide the fact that someone, somewhere, has toactually perform useful work, and this work must itself befunded. It is difficult to establish the right degree of networkingbetween the participants and the degree of overlapbetween modellers, experimentalists, and industrial-

ists. Historically, many pioneering codes were devised inindustry or national laboratories, and then developed inacademia, rather than the reverse. There are very recentexamples of the same routes being taken.There is an important and growing international dimension.Governments often wish to favour their own nationalfirms when funding research. But many of the firms thatmight need modelling are multinational. Others willchange ownership during the life of a project. The internationalcontext cannot be avoided. Likewise, modelling andsoftware are rapidly becoming international activities.Many of the early modelling codes, perhaps until the1970s, were developed within a single laboratory. This ledto duplication of codes with broadly similar capabilities.Code development is increasingly international, partly asa result of electronic communication. Networking withinput from half a dozen countries is hardly consideredworthy of comment any more. Could it be that the mostefficient way to develop modelling software is throughsome form of open-source “e-community”? Who will takethe global lead by encouraging e-communities outside theusual political boundaries, aiming to produce the best softwarein the shortest time?4.1.5. Barriers to the Take-up of Predictive MaterialsModellingIt is often implicitly assumed that either the computer hardwareor the software will be the most serious limitation.The posing of the problem, and the interpretation of theresults, were supposed straightforward. This seems wrong.Whilst major developments in hardware and software arestill welcome, other factors are more limiting. Strong opinionshave been voiced suggesting that the most effectivemodelling is tightly linked to projects, with the importantcalculations at the right level of sophistication. Brainwareand experience, rather than software, are crucial. So whatare the hardest parts? First, framing the problem in a waythat could be modelled (including knowing the level of detailor precision appropriate). Secondly, understandingenough of the modelling output to give adequate answers.Thirdly, knowing the science such that the limitations ofthe models were understood and the value of the answerassessed. The phrases a priori or first principles do not guaranteeacceptance. Fourthly, having enough confidence touse modelling to take unpopular decisions. One importantuse of modelling is to give early identification of what won’twork. Finally, sustaining relatively long-term collaborationsof sufficient numbers of people. This management factorcan be addressed in several ways. One common formatplaces very small teams of modellers (perhaps one person)in an experimental team. However, these isolated modeller(s)can be limited in range of expertise, or may find it hardto keep up to date professionally. An approach, now lesscommon, but with a good history of effectiveness, is to keepa separate modelling group of above critical size, ensuringserious interaction with projects by proper management.Effectiveness is a key point. Somehow, the questions askedand the knowledge gained by modelling should be linkedto the activities of the organisations that create wealth orenhance the quality of life. Useful theory does not proceedin isolation. This linkage can be difficult to achieve, andusually needs receptive scientists in industry with perceptiveand sympathetic managers. Various ways are beingtried to achieve the link between those who model and themain project teams, but there seems to be no consensus onthe best approach.Barriers to the effective use of modelling recur. The firstbarrier is ignorance in industry of what is available or relevant.A related barrier is recognizing that what is availableis not relevant (or not yet relevant). Software houses have amajor interest in removing the barriers. Networks providea very limited answer, limited in that they help those industrieswhich already have quite a lot of expertise to crossthe barriers. The needs are knowledge, not just information,so the World Wide Web (WWW) is far from sufficientas an answer. The third barrier is that there may be no stableindustry team suitably knowledgeable to use the software,if available. Or the industry team may not have a strongenough link with academia or national laboratories to havethe modelling done as a service. Why are stable teams sorare in industry? The usual assertion is “cost.” But paybackis rarely attributed to the modellers, especially when thecontribution was to “kill” a favourite but impossible project.The fourth barrier is technical. Given a problem, oftenincompletely defined, can you get a useful answer intime? Do you trust your analysis of the technical problem,the working approximations, the software, and how youtranslated results into useful actions? Are you still sure, ifyou know that the solution is expensive? The fifth barrier isconvincing others that your own confidence is justified. Alack of previous proven applications, and even academicdisagreement over trivia, can be damaging.4.1.6. What should be done?Our review of the UK predictive materials modelling scenechanged some of our preconceptions. When we were ableto make international comparisons, similar picturesMATERIALS THEORY AND MODELLING133

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART134emerged. The problems, discussed above, suggest a numberof measures to improve matters.Expansion of appropriate courses, looking at and beyondnew graduates. Mature students and those from all nationalbackgrounds should be welcomed, without restrictive(e.g., national) grant rules. “Defining the problem” is moreimportant than training in software use. Since trained studentsare valuable in many roles in industry, numbers shouldnot be limited by perceived needs for specialists alone.Software industries are crucial in transforming sciencebasedcodes into products for non-specialist users. Fundingsoftware development is very difficult. This must changefor scientific software industries to flourish. Developmentshould occur in whichever sector (industry, academia, nationallaboratory) is best equipped. International collaborationsshould be welcome. Software still needs credibility:users do not yet trust electronic structure or mesostructurecalculations, and working assumptions are not intuitive.International competition drives enhancement of hardware.Publicly-funded, state-of-the-art hardware should beavailable to industry under reasonable conditions.Management: Few managers in industry recognize the opportunitiesoffered by predictive modelling. Active groupsin industry are often too small and too transient to be effective.Achievements of modelling are easily underestimated,especially through filtering out flawed proposals. Longertime perspectives are needed than those readily funded.4.2. From Basic Principles to Computer Aided DesignK. Kremer | Max-Planck-Institut für Polymerforschung, 55021 Mainz, GermanyClassical materials science activities in the past largelyfocussed on bulk properties of different materials bycharacterizing them experimentally and analyzing themtheoretically in terms of continuum mechanics models.Condensed matter physics and chemistry, on the otherhand, focussed on fundamental physical and chemicalproperties of systems in the condensed phase. Surface andinterface science was traditionally located somewhere inbetween these two fields.This “old” view has changed dramatically over the last fewyears. Both experimental and theoretical tools have improvedconsiderably so that much stronger links betweenbasic physical and chemical properties at the atomic/molecular structural level and the overall properties of thematerial have been established. At the same time, manydifferent fields of modern technology, such as microelectronics,photonics and biotechnology, require controlleddesign and production of ever smaller structures.In the not too distant future, we can expect that bothtrends, namely decreasing sizes of structures in experimentand the increasing complexity of well characterizedsystems, will meet! In certain areas of biophysics, supramolecularassemblies and micro-optics and electronics,this has already happened!In this context materials theory will play an increasinglyimportant role as it moves more and more from a descriptionof idealized limiting cases towards an almost completetheoretical characterization of the system being investigated.To make progress in this area, coordinated effortsbetween researchers in many theortical subdisciplines aswell as equal interplay between theoretical and experimentalinvestigations are needed.4.2.1. State of the ArtMaterials theory typically employs a “bottom up” approach.To understand properties of complex ordered and disordered,inorganic and organic, and hybrid materials, linksbetween the microscopic atomic structure and the macroscopic“observables” has to be established. At this pointmodern materials science significantly differs from thetypical engineering approach, which is usually not concernedwith this link but rather starts from given properties.Needless to say, both views are complementary andmeet at many points. As the size of the system under considerationincreases, the complexity increases significantly(the number of states typically grows exponentially withthe number of molecules). However, as a consequence ofthe collective many body effects, certain aspects become

even clearer or simpler. Thus a systematic investigation ofgeneric properties beyond the chemical details of a materialwill eventually lead to a more fundamental understandingof its overall properties. This can be illustrated by analmost trivial example. Consider the flow viscosity of apolymeric melt, say standard polycarbonate, an importantglass-forming polymer for many structural but also opticalapplications. The viscosity is a key material parameter forits processing. It can be written as a powerlaw AM 3.4 , whereA is a material and temperature dependent coefficient andM the molecular weight of the polymer molecules. Thispower law is generic and the same for all polymer melts.By changing the process temperature from 500K to 470K,A increases by a factor of ten, a significant technical problem.However, by also increasing M to 2M the viscosity increasesby a factor of ten! Such universally generic as wellas materials chemistry-specific aspects typically have avery similar influence on the overall properties. There is acomplex and often rather delicate interplay betweengeneric and specific aspects in complex materials. This iswhat makes modern materials modelling a great challenge,but also so exciting.Thus Materials Theory, both analytic and numerical, is aninterdisciplinary and wide field incorporating the classicaldisciplines of theoretical condensed matter physics, chemistry,chemical engineering, and, increasingly, biophysics.In order to understand materials beyond (re)producingnumbers, it is important to combine numerical activitieswith analytical theoretical work over a huge variety oflength and especially time scales (over more than 10orders of magnitude!) Only this will enable us to gain afundamental understanding of complex (disordered)materials and allow us to make the next step towards thedesign of new (functional) materials based on theoreticaland experimental knowledge.(a) Electronic structure/quantum calculationsThe general starting point is quantum many-body theory.There are a number of computational techniques whichhave been developed over the last several years which arenow widely used tools, e.g. in catalysis research. All thesemethods are, however, still confined to rather small systemsizes. Most accurate, but also typically only for a few tensof atoms, are the classical quantum chemical methods (CImethods, etc.). Treating the electrons quantum mechanicallybut the nuclei classically is done by the so-called abinitio molecular dynamics (MD) methods (e.g. Car-Parrinelloapproach), based on density functional theory (DFT).This approach, with the use of modern parallel computers,has opened a new and wider field encompassing morecomplicated systems such as biomolecules and catalysistimeAtomistic simulationPolymers: Scales and MethodsQuantum chemistrySoft fluidMesoscopic modelFig. 4.3. Illustration of the characteristic scales for the simulation ofpolymers (Courtesy F. Müller-Plathe, MPI für Polymerforschung).MATERIALS THEORY AND MODELLING135Finite elementlengthSince specific materials or specific systems, like supramolecularaggregates, are mostly the target of investigations,in future the vast majority of theoretical approaches will beof a numerical nature (computer simulations). An indisputablecondition for success will be the supply of computerpower distributed throughout the participating laboratoriesand sufficient CPU time at the high end (supercomputers)combined with the availability of highly qualifiedand motivated personnel. The latter can only be achievedwith competitive working conditions and salaries.The (mainly) numerical techniques, which are used nowadays,can be grouped along the characteristic scales oflength and time they are used for. Of course the borderlinesare not sharp and, with increasing computer power,are removed and shifted continuously (see Fig. 4.3).of polymers (typical system sizes are 10 2 – 10 3 atoms, longesttimes about 10 ps). The next level comprises the lessaccurate tight binding methods. The lack of quantum mechanicaltreatment of the nuclei for ambient conditions isusually not so crucial. However, for many soft matter materialsand for catalysis the presence of the hydrogen atomsis a severe problem. More recently new hybrid approacheswhich link the DFT-MD method with a full quantumchemical treatment of the hydrogen nuclei haveemerged. It should be kept in mind, however, that DFTapproaches generally investigate the electronic groundstate of a system. For excited states, as needed for manyspectroscopic studies, one has to employ a variety of quantumchemical methods. The above approaches form an indispensablebasis for investigations that require specificchemical groups to be distinguished, such as in catalysis,

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART136catalytic pathways, specific interactions of atoms/moleculeswith surfaces, reactivity, crystal growth, corrosion,vibrational properties of anisotropic/disordered systems(polymer crystals, glasses...), and quantum effects insolids, to name a few.(b) Classical calculationsTo treat larger numbers of particles, an atomistic approachbeyond the full quantum mechanical description of asystem is needed. At this level, a classical description ofthe atoms is typically used. However, the interactionpotentials (“force fields”) are derived either directly fromfirst principles quantum mechanical calculations (e.g. forsurface structures) or from a combination of quantumchemical input for the (mostly) intramolecular componentand experimental input as it is done for macromoleculesand molecular assemblies. Current applications for thesetechniques range from surface physics (epitaxial growth,sandwich structures, etc.) all the way to structural anddynamic properties of liquids and amorphous solids, suchas mixtures of molecular systems, synthetic and biologicalmacromolecules, and inhomogeneous systems with complexsurfaces and interfaces. Typical systems can containup to about 10 4 atoms with typical times of up to 1 ns. Forlonger times and larger structural units that go beyond theselimitations, mesoscopic or generic (numerical) schemeshave been developed in recent years. The most prominentclassical example is Monte Carlo simulation of the Isingmodel, which played and still plays a central role in ourunderstanding of critical phenomena (phase transitions).These “coarse grained” models treat a liquid as a collectionof (soft) spheres, a mesogene for a liquid crystal as a littleellipsoid or platelet and a polymer chain as a string ofspheres and springs, or even as a path on an underlyinglattice. The main focus here is on generic properties ofrather large collections of model molecules (polymers,colloids, membranes, supramolecular assemblies, layeredor nanostructural systems, alloys, etc.). Highly optimizednumerical methods are available for workstation/PC-basedsystems as well as supercomputers. Especially for macromoleculesand (supra-)molecular assemblies, this addsqualitatively new features to materials theory. The intramolecularentropy is often of the same order of magnitudeas the intermolecular energies. This interplay can only bedetected when both micro- and mesoscopic information isavailable.To tackle even larger systems, as needed for morphologyformation or many flow problems, (semi-)macroscopicmethods have been developed. Besides the almost classicalFinite Element Methods (FEM), which are widely usedin engineering, new approaches have emerged. This includesa closer link of FEM to molecular properties of theunderlying compound and the connection to Monte Carlosampling for composite materials. Other methods are latticeBoltzmann hydrodynamic simulations, dissipative particledynamics (DPD) for slow/large scale hydro-dynamicssuch as flow of structural liquids, nano-rheology (electrophoresis,nano-electrorheology, transport in molecularassemblies). While the latter two examples are particlebasednumerical techniques, the first is a continuum approach.In between are many others, such as the variousself-consistent field methods (SCF) for molecular systems.Traditionally, these different research areas, essentiallyseparated by length scales or time scales, have been investigatedby different research communities. Massive computerpower is needed to tackle these problems, but evenmore important is the continued coordinated effort ofchemists, physicists, mathematicians, engineers andbiologists. A number of national and EU-wide activitieshave commenced in this direction over the last few years.Such collaboration is absolutely essential to make necessaryprogress but also to stay competitive. This also meansthat sustained long term funding of the individual groupsand (smaller) collaborative teams is needed.4.2.2. Future Research and BreakthroughsBreakthroughs depend to some degree on serendipity andcannot be predicted. However, systematic linking of theabove approaches is a precondition for generating a theoreticalmaterials science which advances from a retroactivedescription of systems to a discipline which providestools with quantitative and qualitative predictive power. Inthe long run we should be able to make the step from moleculeto nanostructure to, in a general sense, function. Thiswill of course need not only the coordinated effort of theoreticians,but also a very close interaction with experimentalistsfrom many different disciplines.The most important developments can be expected in thefollowing areas:• Scale-bridging investigations of complex disorderedmaterials (new basic understanding, improvement ofcurrently used materials).• Correlated quantum systems (quantum computing,etc.), which require new developments in nanocompositesin order to become technically feasible.• Coatings, surface modification of inorganic materials,and use of structured organic and inorganic coatings forfunctional materials.• Structure-function linking: Molecular assemblies,

nanostructured composites for specific functions inbiology, chemistry, medicine, etc.Experiment and technology are continuously enhancingthe precision of measurement and characterization methodsso that structural and functional units of materials anddevices can be made smaller and smaller until their physicallimits are reached. At the other end of the scale, developmentof hardware and software together is allowing thetreatment of more complex and larger units. Thus onedream of materials scientists is to eventually run experimentaland theoretical (i.e. simulation) investigations inparallel in order to provide direct theoretical interpretationof the observed phenomena. In practice, moreover,theoretical work will significantly reduce the experimentaleffort required by screening many possibilities and guidingnew experiments. Since this will have (and already ishaving) a major technological impact, increased attentionis being paid to simulation of materials by scientific andindustrial communities around the world.4.2.3. Competition and the International SituationMany of the above procedures originated from research inEurope or at least were developed significantly by researcherswithin the countries of the EU. The most notable recentexample is the DFT-MD approach introduced by R.Car and M. Parrinello. Also, in the field of statistical mechanicssimulations (coarse-grained models), Europeanresearchers are leading or are among the leading groups.There are many national and international activities whichclearly demonstrate the competitiveness of Europeantheoretical materials science. One indicator of this is themany invited talks European theoreticians are asked togive at international conferences. At the same time, thereare significant efforts being made in the U.S., partly as aresult of the hiring policies of top U.S. universities, partlywithin projects sponsored by the National Science Foundation(NSF) and other funding agencies. Top materialsscience departments (for example, at MIT, Stanford, UCSanta Barbara, UC Berkeley, and the University of Minnesota)are currently increasing their theoretical researchprogrammes. All these activities are characterized by theirclose links among basic experiments, theoretical/numericalinvestigations and application-oriented approaches.Similar acitivities can be found within the Ministry of theEconomy, Trade and Industry (METI, the successor of MI-TI) projects of the Japanese government. The most notableof these is the project currently headed by Prof. M.Doi, in which scientists from industry and university workat the same location on simulations of macromolecules. Itis worth pointing out that many of the theoretical modelsand methods being used there originated from Europe!Competition is increasing as theoretical and simulationmethods come closer to being directly applied in industry.This means that technology transfer from academic to industryhas to be improved, which also requires input fromindustry beyond the current level! In addition, the significantnumber of highly educated and motivated researchersat all levels of their careers leaving Europe to go elsewherehas to be recognized as the chief threat to sustainedprogress in the materials modelling field in Europe. YoungPhD graduates are being vigorously sought by the U.S.,where they enjoy significantly better job opportunities andsalaries. In other words, international competition has tobe met on many different levels.1.2.3.4.5.General ReviewsJ. Baschnagel, K. Binder, P. Doruker, A. A. Gusev, O. Hahn, K. Kremer, W.L. Mattice, F. Müller-Plathe, M. Murat, W. Paul, S. Santos, U. W. Suter,V. Tries, ‘’Bridging the Gap Between Atomistic and Coarse-GrainedModels of Polymers: Status and Perspectives’’, in Advances in PolymerScience: Viscoelasticity, Atomistic Models, Statistical Chemistry,Springer Verlag, 152 (2000) 41.K. Kremer, F. Müller-Plathe, „Multiscale Problems in Polymer Science:Simulation Approaches“, MRS Bulletion (in press).M. Parrinello, „Simulation of Complex Systems without adjustableparameters“, Comp. Sci. Eng. 2 (2000) 22.C. Stampfl, M.V. Ganduglia-Pirovano, K. Reuter, and M. Scheffler,„Catalysis and Corrosion: The Theoretical Surface-Science Context“Surface Science 500 (2001) (and other papers therein).K. Horn, M. Scheffler (eds.), Handbook of Surface Science, Vol. 2:Electronic Structure, Elsevier Science, Amsterdam (2000).MATERIALS THEORY AND MODELLING137

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART1384.3. Theory, Simulation and Design of Advanced Ceramics and CompositesC. A. J. Fisher | Japan Fine Ceramics, Nagoya, JapanFor most of its history, ceramic science has been empiricallybased, due both to the application-driven nature ofits subject matter and the relative complexity and varietyof materials and phenomena it encompasses. One of thestriking features of the last twenty years, however, has beenthe advances made in the field of ceramics theory and simulation,so that in many cases it is now possible to replicateand/or predict the properties of ceramics “in silico”.This has been facilitated by the astounding growth in computingpower over the last two decades, in conjunctionwith the refinement and expansion of simulation algorithms.Computers combine the best aspects of mechanicalmodels (viz. enhanced visualization and manipulation)with the ability to process vast amount of data, and aretherefore excellent tools for testing our understanding ofthe complex nature of advanced ceramics and composites,often providing new insights.Ceramic science forms only one part of the study of materials,itself a highly multidisciplinary field relying on andutilizing concepts from solid state physics, chemistry, solidmechanics, rheology, and engineering, and so on. It is nosurprise, therefore, that many aspects of ceramics theoryand simulation borrow from and build upon knowledgegained from other fields, especially those dealing withmetals and polymers. In this section we focus upon thoseaspects of modern materials theory peculiar to ceramics,and present an outline of the current status of ceramicsresearch, its future needs and priorities.4.3.1. State of the ArtFig. 4.4 summarizes the main techniques currently usedto model ceramics, and roughly indicates the time andlength scales to which they apply. The scope of each of themodelling regimes is constantly being expanded as computationalresources are pushed to their limits. We cantherefore expect greater overlap between the phenomenaand length/time scales handled by different techniques,making it possible to develop reliable multi-scale modellingtechniques (see Sect. 4.3.2).(a) Ab initio and atomistic modellingThe methods used to model ceramics on the atomic scaleare essentially the same as those for simulating metals. Atthe most detailed level, ab initio quantum mechanical(QM) calculations take into account the electronic structureby solving, at some level of approximation, theSchrödinger equation. Despite the remarkable array oftechniques available, calculations are typically performedwithin one of two computational frameworks. Hartree-Fock (HF) theory is the older of the two, and describes thesystem in terms of atomic orbitals, with the many-bodywave function approximated as the product of one-electronwave functions. The second approach is based onDensity Functional Theory (DFT) – usually within eitherthe Local Density Approximation (LDA) or GeneralisedGradient Approximation (GGA) – in which the energy ofthe system is a function of its total electron density. DFT iscomputationally easier to apply to solid state systems, andso will become increasingly important in the study of ceramicsover the next few years. This perception is reflectedin the award of the 1998 Nobel prize for Chemistry toWalter Kohn of the University of California at Santa Barbara,the father of modern DFT.Several academic and commercial software packages areavailable for performing QM calculations, some of the betterknown being CRYSTAL, GAUSSIAN, CASTEP andDV-X. However, these methods are all computationallyexpensive; even with today’s computers, calculations areconfined to at most a hundred or so atoms. Since many ceramicshave large unit cells, this places limits on the rangeof structures and phenomena to which these methods canbe usefully applied. Nevertheless, these methods are vitalfor the accurate determination of the fundamental physicsand chemistry of ceramics, and are already being used byindustry to solve problems where knowledge of electronicstructure is important, e.g. molecule-surface adsorptionduring catalysis.The more general approach to atomistic modelling is toderive “effective” interatomic potentials (sometimesreferred to as “force fields”), that describe the variation inenergy between atoms in analytical or numerical form.Atoms are treated as rigid particles (i.e. the motion of individualelectrons is ignored), although the “shell model” canbe used to take into account electronic polarization. Usingthese potentials, of which there is a wide variety ranging insophistication from the simple two-body Lennard-Jonestype to multi-body Embedded Atom Method (EAM)potentials, much larger systems can be studied – up to a

million atoms on today’s supercomputers. More commonly,simulations are performed with empirical potentials onworkstations and the latest PC’s for a thousand to tens ofthousands of particles.The chief difference between atomistic simulations ofceramics and other substances is the need to take intoaccount the long-range Coulombic interactions betweencharged particles, as many ceramics are at least partiallyionically-bonded. The Coloumb energy, which falls off as1/distance, is traditionally handled by the Ewald method,although other methods, e.g. the Fast Multiple Method(FMM), are increasingly being used in an attempt toreduce the amount of computational time spent in thiscritical part of the simulation.Once an atomic interaction model has been selected,essentially the same techniques for simulating metallicand polymeric systems can be applied to oxides, nitrides,carbides and other ceramics (see Fig. 4.4). These methodsare now used routinely to predict the properties of perfectcrystals, bond states, defects, surfaces and grain boundaries,covering phenomena such as surface catalysis, solutionenergies, atomic diffusion, wetting, friction, crackgrowth and phase changes. The chief challenge for atomisticmodelling over the next decade will be to developreliable interatomic potentials that are transferablebetween different compounds and coordination environments.This has motivated the development of semi-empiricalmethods, such as the Tight Binding (TB) method,which, although more time consuming than fully empiricalmethods, provide increased accuracy and are appropriatefor a wider range of bonding environments. Anothermajor challenge will be to overcome the short length andtime scales to which atomistic simulations are currentlylimited, particularly in the case of dynamic simulations, sothat a wider range of phenomena, such as “normal” (nonrapid)ionic diffusion in crystals, can be simulated.(b) Meso-scale modellingMost ceramics are used in polycrystalline form, and it haslong been recognized that a ceramic’s microstructure has aprofound influence on its properties, including appearance,strength and corrosion resistance. A major goal ofcurrent research is therefore to develop, based on both establishedand yet-to-be-developed theories of sinteringand grain growth, simulation methods that can reliablyreproduce the time-evolution of microstructures. Computersimulation allows the simultaneous solution of largenumbers of non-linear equations, and therefore provides ameans to consider several mechanisms in the same model.However, apart from a few examples, computer simulationsstill can not routinely and reliably describe the behaviourof real materials due to simplifications necessary tomake the calculations tractable. Nevertheless, many simplifiedmodels have provided a sound basis for understandingthe basic mechanisms involved in microstructuralMATERIALS THEORY AND MODELLING139Static MethodsLength, lFig. 4.4. A schematic representation of the time and length scalescovered by different techniques used to simulate ceramics.metrescentimetresMACROComputationalThermodynamicsmillimetresFinite Element AnalysisLattice DynamicsmicrometresStatic Methods (t = 0)Potts ModellMonte CarloContinuum ModelsMESOMolecularStaticsAb initionanometresÅngstrømsMolecularDynamicsMICROmillisecondsmicrosecondspicosecondsnanosecondsseconds hours monthsTime, t

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART140development, and are an important step in the formulationof more sophisticated general theories.Most techniques for modelling the meso-scale are continuummethods. These have been used to describe a vastrange of phenomena from ceramic processing (extrusion,pressing, slip-casting, thermal spraying, etc), sintering,Zener pinning and Ostwald ripening, to ferroelectric domainswitching in magnetic ceramics and crack-bridgingin composites. They are usually based on principles suchas constitutive theory and balance laws from solid mechanics,thermodynamics or the Cahn-Hilliard and Ginzburg-Landau equations. Common techniques from other fieldsare now also being successfully applied to ceramics, e.g.the Cellular Automaton method and Population Balancemodelling.Unlike continuum techniques, the Potts Model MonteCarlo method does not rely on explicit input of thermodynamicand kinetic characteristics into the model. The“ceramic” is represented on a square or triangular lattice asan agglomerate of particles with different interface energies,and statistical sampling is performed to find configurationsof increasingly lower energy. Methods have beendeveloped for treating grain growth and crack propagationin multi-phase systems, as well as complicated phenomenasuch as liquid phase sintering, an important process inthe formation of many ceramics. 2D simulations can oftenreproduce the chief characteristics of microstructuralevolution of ceramics, while 3D models are often necessary,despite the large increase in computational costs theyentail, for quantitative agreement with actual materials.The primary limitation of this method is in deciding on therange and relative size of the interface energies, althoughthis may be overcome in the future by using multi-scalemodelling techniques.(c) Macro-scale modellingMany macro-scale processes, such as those involved in theformation and use of ceramic components, have been successfullymodelled using Finite Element Methods (FEM).This is one of the earliest techniques applied to materialsmodelling, and is used throughout industry today. Manypowerful commercial software packages are available forcalculating 2D and 3D thermomechanical, electromechanicaland optical properties/processes (e.g. indentationresponse, densification, and piezoelectric effects). Recentdevelopments in Continuum Damage Mechanics (CDM)theory allow FEM to be used to treat fracture, crack growthand related phenomena. FEM is the simulation methodclosest to real ceramic applications, usually relying on alarge database of measured materials properties as input.Another successfully applied field of “macro-scale” modellingis computational thermodynamics. Software packagessuch as Thermo-Calc, Chemsage and Fact use thelaws of thermodynamics and large databases of thermodynamicdata to predict phase diagrams and the chemicalstability of single, binary and multiple phase ceramicsystems at various temperatures and pressures. This fieldalso includes the rapidly advancing field of first-principlesand statistical thermodynamics calculations of inorganicmaterials. Computational thermodynamics thus has theunique position of being applicable to all length scales.Unfortunately the influence of metastable phases, kineticeffects and non-equilibrium conditions, which strongly affectthe microstructure and properties of ceramics, cannotyet be handled adequately. Such methods are currentlybeing developed for metallic systems, so it is reasonable toassume that ceramic scientists will extend their use toceramic materials in the near future.4.3.2 Future Research Goals and PrioritiesThe interplay between theory, modelling, experiment andfinal application of ceramics is illustrated in Fig. 4.5. Theultimate goal is to reduce the dependence on experimentand empirical measurement, and perform at least thepreliminary stages of materials selection and design oncomputer. From an industrial viewpoint, the aim is toreduce both the cost and time of developing materials fornew applications, or to replace materials in current applicationswith new, improved ones, for reasons of cost, performanceand/or environmental compatibility. In pursuitof this target, the following trends and priorities for ceramics-relatedsimulation have been identified.(a) Ceramics theoryNowadays theory and simulation are often closely interrelated,with one serving to confirm and/or modify the otherin a symbiotic fashion. As experimental techniquesbecome more precise, with many devices now capable ofmanipulating structure on the atomic level, our ability tocompare theoretical predictions directly with experimentvia computer simulation is increasing. There is no doubtthat novel phenomena in advanced ceramics await to bediscovered – and also explained – well into the future.Indeed, adequate theoretical explanations for some phenomena,such as superconductivity in cuprate ceramicsand the varistor effect in zinc oxide ceramics, are stillbeing sought. Other underlying theories used in ceramicssimulation are on the whole well established, e.g. quantummechanics, thermodynamics, fracture mechanics and

Ceramic TheoryQuantum physics, solid state chemistry,solid mechanics, fluid mechanics,fracture mechanics, pecolation theory,thermodynamics, rheology, etc.Atomistic ModellingMethods:• Ab initio (Hartree-Fock, DFT)• Molecular statics• Molecular dynamics (MD)• Quantum mechanical MD• Monte Carlo (MC)• MD/MC hybrids• Lattic dynamicsComputer SimulationMicrostructure ModellingMethods:• Potts Modell Monte Carlo• Cellular Automata• Diffuse-interface model• Phase Field models• Voronoi methods• Population Balance modelsExperimentImproved analysis and synthesis methodsMacro-scale ModellingMethods:• Finite Element Methods (FEM)• Densification models• Computational thermodynamicsMATERIALS THEORY AND MODELLING141Multi-scale modellinglink anatomic and/or micro-scale to macro-scaleMaterials ApplicationsNew and improved ceramicsFig. 4.5. Idealized interaction between ceramicstheory, simulation and experiment.dislocation dynamics. Challenges arise in applying andextending these to the structural and/or compositionalcomplexities typical of advanced ceramics and composites.The brittle nature of these materials means that theirphysical properties are often controlled as much by theirmacro-scale and microstructural conformation as by theirchemistry. More comprehensive and “holistic” theoriesof microstructural evolution over short and long time periodsneed to be developed if the properties of ceramicsare to be properly understood, controlled and improved.(b) Multi-scale modellingFig. 4.6 lists several short-term and long-term priorities forresearch into simulation techniques for given length scales.Although these are very important for understandingcertain phenomena within specific fields, from the pointof view of overall materials design, the development ofmethods for performing “multi-scale” or “hierarchical”modelling is perhaps the most pressing need.“Multi-scale” modelling is the combination of various techniquesthat treat disparate length (and time) scales into asingle consistent simulation. The simplest approach is touse output from small-scale simulations as the input tolarger scale calculations, the so-called “bottom up”approach. Other strategies incorporate feedback loops, orperform detailed, computationally expensive calculationsonly at critical points in the simulation. Hurdles that needto be cleared include deciding where the transition from“discrete” to “continuum” behaviour occurs, and howrepresentative small-scale simulations are of large-scalephenomena.The concept of multi-scale modelling has been applied tosimulation of metals for several years now, but it is onlyjust beginning to be pursued by modellers of ceramics.Two recent examples include atomistic simulation of crackfronts combined with continuum treatments for the surroundingmatter, and Potts Model Monte Carlo simulationof microstructure in combination with stress-strain

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART142and temperature distributions from FEM. Successfuldevelopment of these methods will undoubtedly requirelarge investments of money, brain and computing power.However, in terms of the reduction in use of raw materials,improved properties and performance, and reduced productdevelopment time for advanced ceramics and composites,the rewards will be substantial.(c) Synthesis and processing of ceramicsThe fundamental nature of sintering and grain growth andits influence on the properties of ceramics, particularly forengineering and structural applications, means that reliablesimulation techniques will be in great demand in theyears ahead. Atomistic, microstructural and macro-scalesimulations all have a part to play in elucidating the mechanismsinvolved. Only a multi-scale model, however, willbe able to handle the interactions between differentmicrostructural components and macroscopic conditions,and it is difficult to envisage any other means of reliablypredicting the microstructures of actual ceramics solelywithin the computer. A great deal more research, both theoreticaland practical, needs to be done before such techniquesare realized.The increasing importance of chemical methods for synthesizingadvanced ceramics, particularly solution-basedprocessing and gas phase methods (e.g. chemical vapourdeposition), means that increased attention should be paidto modelling these systems as well. Analytical models,including FEM and fluid dynamics, have been used tostudy such processes, but more work remains to be doneon simulating processes such as pyrolysis, crystal growthand gas phase reactions from the atomic and nano-levels.(d) Smart materialsIrrespective of whether a material is intended for functionalor structural use, simulation methods are available (albeitwith different levels of accuracy) for investigating its physical,chemical, electronic and mechanical behaviour. Indeed,the growing field of smart materials, in which both functionality(e.g. sensing) and structural integrity (e.g. strength ordurability) are combined in the same ceramic or composite,will greatly benefit from the use of computer modelling forthis very reason. Models that can take into account multiplefactors such as grain size, diffusion rates, external pressurelevels, and so on, will allow the behaviour of smart materialsto be predicted and optimized faster than would otherwisebe possible by trial-and-error experimentation.(e) NanoceramicsAs part of the nanotechnology drive of the late 1990s, workcommenced on the development of nanoceramics, withtheir promise of superior properties and possibly even newphenomena. Because of the length scales involved, atomisticand microstructural simulation techniques naturallylend themselves to the study of these materials. Combinedwith advances in high-resolution instrumentation(for calibration and validation of simulation/theory) andprocessing (for manipulating ceramics at the nano-scale),these simulation techniques will become essential tools inthe study and design of nanoceramics. As components(e.g. crystal grains) become smaller, the relative proportionand importance of interfaces increases, so that theuse of simulation techniques to understand interfacestructure and behaviour will be a central part of nanoceramicsresearch.(f) Interface scienceNot only in nanoceramics, but also in most polycrystallinematerials and especially composites, interfaces play animportant, often crucial (e.g. zinc oxide varistors) role indetermining a material’s properties and performance. Amajor goal of materials research over the next few yearswill therefore be the simulation and eventual design ofinterfaces, inlcuding grain boundaries and surfaces.Bonding of ceramics to other materials, e.g. ceramic coatings,is an important technological issue that will requiresubstantial research and innovation. New methods formodelling interfaces in heterogeneous and/or multi-materialsystems (e.g. ceramic-polymer and metal-ceramicinterfaces) need to be developed, since the fundamental[001]-axis (perpendicular to interface)[100]-axis (in a TiO 2 -layer)Mo/SrTiO 3 (001) contact: local density functional theory (ab initio mixedbasispseudopotential calculations): electron density differencebetween interface and free surface, showing Mo-O nearest-neighbourbonds and Mo-Ti next-nearest neighbour bonds across the interface(Th. Classen and Ch. Elsässer, MPI für Metallforschung Stuttgart).

Functional CeramicsAtomistic ModellingShort term:• Improve interatomic potentials• Quantify entropy effects• Develop non-equilibrium techniquesCeramics Theory• Explain underlying physics, e.g. colossalmagnetoresistance, varistors,superconductors, proton conductivity• Develop better theories of macroscalephenomena, e.g. sintering, creep• Explain transition from quantum toclassical, and discrete to continuum• Predict new phenomenaMicrostructure ModellingShort term:• Increase complexity/include multiplemechanisms• Include kinetic effects• Extend to 3DLong term:• Reliably predict microstructures andrelated propertiesStructural CeramicsMacro-scale ModellingShort term:• Improve/enlarge databases• Develop models for new processingtechniquesLong term:• Predict component lifetimes• Predict component properties, e.g.strength, oxidation resistance,piezeoelectric performanceMATERIALS THEORY AND MODELLINGLong term:• Increase length and time scales byorders of magnitude143Multi-scale modellingShort term:• Develop concepts via specific examples• Include kinetic effectsLong term:• Predict properties and/or performance from first principles• Design of new and improved ceramicsFig. 4.6. Research priorities andobjectives for development ofceramics theory and simulationover the next 5 to 10 years.differences in bonding, structure and symmetry betweendifferent phases make them difficult to simulate with currentmethods. In addition, the virtually infinite number ofpermutations of interface orientations, segregation effects,strain and defect states in real materials needs to be takeninto account. Assuming that time- and length-scale limitationscan be overcome (e.g. using new methods such ashyperdynamics, parallel replica dynamics or temperatureaccelerateddynamics), atomistic simulations will becomeimportant sources of data about the structure and propertiesof ceramic interfaces. For macro-scale componentswith nano-level organization, one possible scenario is thatresults of atomistic methods are used to test and/ordevelop general principles, and these scaled up for largersimulations via some multi-scale modelling schema.(g) Design of ceramicsDespite active research and significant progress over thelast decade, materials modelling has yet to have a significantimpact on the design of advanced ceramics. This isperhaps not surprising given the newness of the field andthe small numbers of researchers in it. Generally speaking,given the time it currently takes to develop, validate,perform and interpret computer simulations, it is still oftenfaster to run a large series of experiments on differentmaterials and pick the best one. To overcome this “timelag”,and exploit the potential of computer modelling tostreamline and improve the design process, more robustsimulation techniques and software will need to be triedand tested over the next decade, with input from industryand software companies. This process is expected to occurfaster for ceramics used in functional applications, suchas sensors and electronic components, where miniaturizationand improved synthesis methods provide greatercontrol over a material’s composition, structure and behaviour,than for structural ceramics, where the number ofcontrollable and uncontrollable variables is greater.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART144One example of the potential of computer modelling torevolutionize materials design is a recent report in Natureof the use of computer simulations to predict the existenceof an ultra-hard phase of TiO 2 . This new phase was subsequentlysynthesized, and found to have properties close tothose predicted. It should also be pointed that in certainareas where the materials problem is well defined, such asuse of zeolite catalysts and molecular sieves in the petrochemicalindustry, computer simulation has been makinguseful contributions to materials design for some time.Between the extremes of “molecular design” and “componentdesign” lies the field of microstructural design. Althoughlikely to take longer to develop, tools for simulatingceramics microstructures will have an enormous impacton the design of ceramics, resulting in improved strength,toughness, high temperature stability, thermal conductivity,etc, and largely replacing the “trial-and-error” methodsused today. Depending on how rapidly multi-scale modellingtechniques can be realised, the computational designof ceramics and composites from the nano- and microlevelsto the final component should be feasible within thenext ten to fifteen years.4.3.3. Research InfrastructureCompared to metals, polymers and “biotech” materials,the number of researchers modelling ceramics is relativelysmall. This imbalance needs to be addressed by supportfor both basic research into advanced ceramics as well astheir high-tech application. Similarly, many of the problemscurrently encountered in ceramics theory will onlylikely be solved by combined contributions from researchersin different fields. It is therefore important to promoteinterdisciplinary collaboration, particularly between physicists,chemists, materials engineers and computer scientists.Students should also be encouraged to learn both experimentaland simulation techniques for studying advancedceramics and composites.To remain at the forefront of materials simulation, Europeanlaboratories will need access to increasingly fasterand more powerful computers. The cheapness and ubiquityof personal computers (PCs) means that an economicway of constructing a parallel processing system for handlinglarge-scale simulations is to connect several PCs in asimple array network. There is still a need for access tosupercomputing facilities, however, for large research andcollaborative efforts, particularly in the case of atomistic/quantummechanical calculations. For example, ultralarge-scale(supra-million atoms) simulations for investigatingphenomena on the micron level will require massivelyparallel architectures to be performed in a reasonabletime frame.Europe is in an excellent position to take advantage ofadvances in computer modelling of ceramics and compositesbecause of its core of top-class theoretical researchersand its tradition of innovative thinking in the physicalsciences. Research teams from the UK and Germany, aswell as many from Italy, France, Switzerland, The Netherlandsand elsewhere, lead the way in many areas of ceramicstheory and modelling. Fostering of researchers,theoreticians and experimentalists within the Europeanframework, as well as internationally, should therefore begiven high priority to ensure continued progress in thisfield and also to give European industries the competitiveedge they need in an increasingly high-tech world.4.4. Modelling Strategies for Nano- and BiomaterialsH. Gao | Max-Planck-Institut für Metallforschung, 70174 Stuttgart, GermanyThe science and technology of materials have often beensaid to set the milestones of human progress. Indeed,important stages in the history of civilization are often referredto as the Stone Age, Bronze Age and Iron Age. As weenter the first decade of the 21 st century, we can look backon the tremendous impact and benefit materials technologyhas had on human life. At the same time, we are enteringone of the most exciting eras in terms of acceleratingtechnological innovation in the history of mankind. Thereare unprecedented opportunities for improvements inhealth and standards of living for humanity as a whole. Theinterdisciplinary boundaries between materials scienceand biology, physics, and chemistry will provide fertileground for establishing a new knowledge base for emerg-

Time (s)10 2110 -210 -410 -610 -8ing nano- and biomaterials technologies. These researchareas, while providing tremendous opportunities forscientific discoveries and technological innovations,demand intensified efforts to develop new theories andmodelling strategies for complex materials systems.The main purpose of this article will be to show that materialstheory has been a basis and guide for the developmentand improvement of new generations of materials in theaerospace, automotive and microelectronic industries.There is no reason to suspect that theory will play any lesserrole in the emerging nano- and biomaterials fields. Infact, we strongly believe that theory will play a more importantrole because the complexity of the systems used in(2010)With a few exceptions,no suitable methods(2001)Classical continuum theoriesFEM, Solid and fluid mechanics(plasticity, viscoelasticity, …),Energy and mass transport theories,Diffusion equations.Mesoscopic theoriesContinuum gradient theories,Lattice Boltzmann, Monte Carlo,Particle hydrodynamics, etc.MD, Tight binding10 -10 Ab initio10 -10 10 -8 10 -6 10 -4 10 -2 1Time (s)10 2110 -210 -410 -610 -8Length (m)Fig. 4.7. The state of the art and present frontiers of theoreticalmethods in materials modelling in terms of length and time scales ofapplicability. The yellow region represents problem areas wheremethods have been developed and the orange region represents areaswhere no suitable methods presently exist. The dotted line is theprojected frontier by 2010.Biological and biomimetic materialsProteinsCellsNanotechnologyMicrotechnology:MEMSElectronicsTissuePolymeric materialsStructural materialsOrgans10 -10 10 -8 10 -6 10 -4 10 -2 1Length (m)these new areas can only be overcome by combiningexperimentation with effective modelling. We stronglyrecommend that modelling and simulation be includedas essential parts of all present and future Europeanprogrammes on materials research.Modelling has played an indispensable role in the developmentand improvement of new materials for industrial, militaryand civilian applications. The past two centuries havewitnessed tremendous progress in our understanding ofmetals. The field of metallurgy has evolved from an art to ascientific discipline firmly based on the theories of dislocation,creep, fatigue and plasticity. Tremendous progress hasalso been made in our understanding of ceramics, glass,semiconductor, and polymer materials. On the other hand,our understanding of nano- and biomaterials such as quantumdots, nanostructures, molecular assembly, proteinsand DNA molecules, is still at a very primitive stage. Similarly,while synthesis and processing of many structural materialshas reached a state of maturity, there is a general lackof theoretical understanding on nano- and bio-synthesismethods including thin film growth and processing, nanofabrication,biomimicry and self-organization. This is dueto the complexity of these processes and insufficient understandingof the underlying physical principles.Classical methods in materials theory include solidmechanics, fluid mechanics, the finite element method(FEM), diffusion theories, thermodynamics, and statisticalmechanics. One can hardly think of any industrialapplications where at least one of these theories has notplayed a crucial role in its development. The theories ofsolid and fluid mechanics, including structural mechanics,strength of materials, plasticity, fracture, and aerodynamics,have guided the development of new materialsand new design methods now widely used in the aerospace,civil engineering, automotive, nuclear and computerindustries. Quantum electronic theories have formed thebasis of device physics in microelectronic and optoelectronicindustries. While the theories of dislocations, plasticity,fracture and creep have guided the developmentof materials such as superalloys, polymer composites andceramic composites, quantum simulation techniques havenow been introduced to investigate and/or design molecularmaterials such as nanotubes, proteins and new pharmaceuticaldrugs. Modelling and simulation techniquesaffect all stages in the development and improvement ofnew materials, from the initial formation of concepts toFig. 4.8. Typical length and time scales for a number of technologicalareas where materials modelling and simulation are essential.By overlaying this plot on Fig. 4.7, it can be seen that there arepresently no suitable methods to treat much of the nano- andbiomaterials technology within realistic length and time scales.MATERIALS THEORY AND MODELLING145

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART146synthesis, characterization and properties. For example,the FEM method is widely used to evaluate design concepts,to optimize testing and fabrication methods, and tolink structural and functional performance to microstructureof materials.Recent decades have also witnessed tremendous progressin quantum and atomistic simulation methods such asDFT. An overview of the state of the art of such methodshas already been discussed in Sect. 4.2. Quantum simulationsare now being used to study the behaviour of nanostructuressuch as carbon nanotubes and a myriad ofbiological molecules such as various types of proteins,membrane lipids and vitamins. These simulation methodsare not only limited by the number of degrees of freedombut, more importantly, also by the time scale. Typically, abinitio quantum methods are applied to system sizes of afew hundred atoms and time scales up to a few picoseconds.In comparison, classical molecular dynamics methodsare based on direct time integration of Newton’s lawsof motion and can now treat systems of up to one billionatoms with time scales on the order of nanoseconds. Theserestrictions often limit the application of quantum methodsto the study of nano- and biomaterials. One possibleremedy to this problem is to develop mesoscale theories tobridge the ab initio quantum concepts and continuummethods. Present examples of such mesoscale theories arecontinuum gradient theories, Boltzmann transport theories,Monte Carlo methods, and particle hydrodynamicsmethods. Another promising approach is Voter’s time ortemperature accelerated molecular dynamics methods.Advances in computing power in the next decade willsignificantly expand the regime of applicability for manyof these methods.Based on past experience, it should be possible to extendthe time scales of quantum and atomistic methods by oneor two orders of magnitude by 2010.4.4.1. State of the Art and Present FrontiersFig. 4.7 shows a schematic representation of the currentstate of the art of materials theories with respect to bothlength and time scales. Typically, classical continuumtheories are phenomenological theories based on fundamentalphysical principles requiring empirical parametersdetermined from experiments. As such they are oftenlimited to large length scales (above 1 µm) with few timescale limitations. In contrast, ab initio quantum methodshave in principle no empirical parameters, hence requiringno fitting with experimental data. Such methods should inprinciple be able to predict experimental outcomes, andhence be extremely powerful. Their main limitations arethe short time scale and computational expense, whichoften prevent them being directly applied to real engineeringproblems. In between the ab initio and classicalmethods are a host of mesoscale methods that have beendeveloped to bridge the gap between quantum and continuummethods. With a few exceptions (for example, elasticitytheory), there are usually no suitable methods to treatproblems with system sizes on the order of microns andtime scales spanning microseconds and above. On thesame length-time plot, Fig. 4.8 shows typical length andtime scales for a number of areas of technological application.Comparing Fig. 4.7 and 4.8, one sees that whileexisting theories are most mature for structural materialapplications, much of the emergent technology areas concerningnano- and biomaterials require new theoreticaltools that are not available to date. For example, proteinconformation and folding is one of the most importantproblems in biomaterials. A comprehensive investigationof such problems would require the development of theoriesthat are appropriate for length scales from a few tensof nanometres to one micrometre and above and time scalesfrom microseconds and beyond. Development of methodsfor these length and time ranges should be achievable bythe next generation of theoretical materials scientists andwill provide significant economic benefit to society.4.4.2. Possible Areas of BreakthroughsOverlaying Fig. 4.8 on Fig. 4.7 reveals that the centralissue of computational materials science is to develop newtheories applicable to small length scales and large timescales. Such efforts have the potential to lead to revolutionarybreakthroughs in materials modelling and shouldreceive the highest priority for research. Also, four possibleareas for more breakthroughs that can have a large impacton emergent materials technologies in the coming decade:(a) New modelling strategies for complex materialsystemsAt present it still seems unlikely that we will be able totreat all of the interesting problems by ab initio methods,at least not in the forseeable future. Even if this were tobecome possible, the analysis of the enormous amounts ofdata generated from computer simulations would itselfrequire massive computing power and a comprehensivemodelling strategy. Therefore, we need to consider modellingstrategies for complex material systems. Such modellingstrategies should focus on the multi-scale and multiphysicsnature of emergent problem areas in materials

New strategies for modelling of complexmaterials systems, e.g. disordered materials,surface and interface phenomena.Computer guided design and fabricationmethods for nanotechnology.New theories applicable at small lengthscales and large time scales.Simulation-based design of new functionalmaterials.Modelling of biological and biomimeticmaterials.MATERIALS THEORY AND MODELLINGscience. An example might be disordered materials such aspolymeric materials where quantum chemistry methodsmust be used together with atomistic simulations andfinite element methods to model phenomena ranging fromelectronic structure to molecular structures to polymerdomains to macromolecular conformation and the macroscalecontinuum.(b) Simulation-based design of new functional materialsNew integrative methods that bridge modelling at the materiallevel (e.g., composition, structure, morphology) tothe functional level (e.g., quantum dots, conducting orsemiconducting nanotubes, enzymes) will revolutionizethe way that new materials are discovered and developed.New methods for small length and large time scales willbe especially important for this development. An examplewould be the design of molecular electronic devices for futureinformation technology (Fig. 4.9).Snapshots of 1-billion-atom molecular dynamics simulations ofwork hardening in a copper single crystal (F. Abraham, H. Gao andcoworkers): Dislocations are nucleated at two pre-exisiting cracks.The resulting plastic flow has significantly blunted the crack tips.Fig. 4.9. The priority research areas for materials theory. The centralblock represents the core activity that should lead to revolutionarybreakthroughs in theories and methods applicable to problems withsmall length and large time scales. The four surrounding blocksrepresent more evolutionary paths that can nevertheless have a largeimpact on emergent materials technologies.(c) Computer guided methods for nanotechnologyPredictive methods to guide nanofabrication will be requiredfor the nascent nanotechnology industry. Thesemethods must be firmly based on physics and have thecapability of simulating the nanofabrication process underrealistic conditions. One example is the use of kineticMonte Carlo methods together with ab initio methods tomodel deposition and self-organization of nano-grainedmagnetic media for the next generation of information storagedevices. In such a scheme, information from ab initiocalculations at the unit cell level is passed to a MonteCarlo algorithm via an event catalogue to simulate the selforganizedatomic deposition process.(d) Modelling of biological and biomimetic materialsMaterials scientists have the opportunity to make significantcontributions to the development of biological materialsfor both medical and engineering applications. Forexample, one of the emerging areas of research is tissueengineering where physics and engineering principles areapplied to guide the differentiation of biological stemcells to form specified tissue or organs for medical applications.Questions of how cells interact with patternedor unpatterned metal, ceramics and polymer substratesare important for the development of bio-compatible andbiodegradable scaffolds. There are tremendous economicbenefits to be realized and, at the same time, manyimportant scientific questions. Conversely, in the field ofbiomimetic materials one tries to learn from biology thebasic principles used by natural evolution to constructmaterials with superior properties such as adhesion, hardness,and mechanical strength. For example, naturally147

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART148occurring materials such as sea shells are made of nanocompositesconsisting of alternating layers of mineralsand proteins. Such composites exhibit mechanicalstrengths which are orders of magnitude higher than theconstituent phases alone. The mechanisms by which suchhigh strength is achieved are still not well understood. Bymultiscale modelling and simulation, we hope to learn thebasic principles of biological materials and achieve similarmaterials design in the laboratory through micro- andnano-fabrication methods.In each of the above examples, modelling plays a crucialrole in hypothesizing and formulating basic principles andguiding the development of new materials.4.4.3. Strategic Alignment of Europe with respect to theU.S. and JapanWith the rapid globalization of the world economy, Europeis facing increasing competition from the U.S. andJapan. The U.S. is heavily investing in nano- and bio-technologies,as reflected by the fact that the funding for theU.S. National Institute of Health has quadrupled over thelast 5-10 years and this trend is increasing at an exponentialrate. At the same time, the National Science Foundation(NSF) has officially recognized nanoscale modellingand simulation as the major pillar of nanotechnology andis in the process of implementing a series of new initiativeson nanoscale materials modelling. Biomedical engineeringdepartments are being founded at all major U.S.universities (MIT, Stanford, Columbia, Johns Hopkins,Georgia Tech, etc) and are strategically oriented to becomingthe major research direction in the 21 st century.There is a dramatic increase in the number of studentsenrolling in life science courses. For example, more than50% of the undergraduate students at Stanford Universitydeclare their major to be related to the life sciences. Itis estimated that there will be about 200 new faculty positionsin the U.S. in the field of bio-engineering within thenext 3 years. Japan is also leading in several key areas ofmicro- and nanotechnology, especially in the areas of optoelectronicsand nanoelectronics. As these technologiesare essential for its economic well-being, Europe simplycannot afford to yield the competitive edge to the U.S.and Japan and must take immediate action to establishand maintain a sound scientific base for these newlyemerging technologies.4.4.4. ConclusionsThere are enormous new opportunities for research inmaterials theory in the areas of nano- and biomaterialstechnology. New theories or methods for applications withsmall length and large time scales are likely to lead torevolutionary breakthroughs. In addition, we recommendfour modelling areas that have the greatest potential forindustrial impact in the next decade. These areas are newmodelling strategies for complex materials systems, simulation-baseddesign of new functional materials, computer-guidedmethods for nanotechnology, and modelling ofbiological and biomimetic materials.ConclusionsTheoretical modelling of materials has proven to be a successfuland valuable part of the science and engineeringof materials. The applicability of materials theory to almostany established and newly emerging topic of materialsscience (see Fig. 4.2) promises that it will play an increasinglyguiding, stimulating and visionary role in the searchfor novel materials. This observation necessitates increasedattention to and funding of theory and modellingwithin materials research programmes in Europe.The reason for the success of materials modelling is itsability to quantitatively model and predict the complexstructures and properties of real materials. Consequentlyit will soon be possible to “create” novel materials anddevices by theoretical means, ranging from structuraldesign via synthesis routes to functional properties. Thispredictive power originates from the fact that the microscopicconcepts of modern materials theory are groundedon principles of solid state physics and chemistry fordescribing interactions between nuclei and electrons.

European researchers in academic and industrial laboratorieshave contributed considerably to this success in thepast, and the European Commission as well as nationalagencies in the European Union set up funding programmesthat made this possible. Now more than ever, aconcerted effort is needed to maintain Europe’s position(in many cases a position of leadership) at the cutting edgeof materials theory and modelling. Without suitable planningand support from government and industry, Europeanswill miss out on the economic and social benefitsthat materials modelling will bring. To avoid such a situation,the following recommendations are made:• European industrial companies should also foster longtermmaterials theory groups, and provide attractivepositions to materials theoreticians who are encouragedto think innovatively and help in the design and developmentof industrial products.• European “Materials Modelling Centres” and networksshould be established similar to those set up in the U.S.in recent years. These could serve as “intellectualhothouses” for the development and application of computationalmodelling methods, and house Europeansupercomputer facilities for large collaborative projects.MATERIALS THEORY AND MODELLING• Improved transfer of scientific expertise and computationaltools between academic researchers at universitiesand research laboratories operated by publicorganisations on the one hand and industrial scientistson the other.This will allow academics to apply their expertise to importantissues and problems in the industrial applicationof materials, and to educate and train the next generationof students with the skills they need. Industry will benefitfrom access to the latest ideas and having the materialssystems they are interested in being studied sooner. Jointacademic/industrial research projects will motivate studentsto pursue careers in materials modelling because ofthe challenging and relevant problems they can work on.• European universities and non-industrial research laboratoriesare encouraged to establish Materials Theoryas a substantial part of their research strategies andpromote interaction between theoreticians and experimentalistsfrom different disciplines.The cross-disciplinary nature of this field can be exploitedto stimulate students’ interest by including materials modellingcomponents within the curricula of natural science(physics, chemistry and biology) and applied engineeringdegrees. At the same time, faculty positions for materialstheorists will be necessary to provide quality teaching inthis field.With regards to academic research, materials modellingwill benefit greatly if traditional distinctions betweenexperimental and theoretical groups can be broken down.For instance, teams of experimentalists and materials theoristsworking together on the same problem (whether it befundamental phenomena or device development), withthe increased communication and understanding thiswould bring, should greatly accelerate materials researchas a whole.• The continued expansion of the Internet should also beencouraged, and upgrading of communication networksto the latest technology (e.g. ISDN broadband) shouldbe considered a priority.The Internet has played an important role in the developmentof materials modelling by: 1) facilitating rapid communicationbetween researchers, 2) allowing rapid publicationof results, and 3) providing connections to remotesites, e.g. for transfer of data to and from supercomputers.Already several software and data repositories exist thatare freely accessible by anyone, and their growth shouldbe encouraged.• Research into faster and more powerful computersshould continue.The backbone of all computer modelling is the hardware ituses. Research into the next generation of computersshould therefore be supported. Europe is at the forefrontof research into optical and quantum computers, and stepsshould be taken to ensure that this technology is developedand marketed by European industry. These technologiespromise to be orders of magnitude faster than conventionalelectronic computers, and will revolutionise materialsmodelling at all levels.149

CHAPTER 55. MATERIALS PHENOMENA150151The science of materials may perhaps be described asthe physics and chemistry of materials behaviour, asexhibited by the phenomena observed by subjectingmaterial substances, usually solids, to some action. Time andagain new phenomena are discovered. Recent examplesinvolve superplasticity and high T c superconductivity, whichphenomena are also of great potential for practical application.Materials phenomena are usually classified according to fourbroad categories: mechanical/physical, thermal, electrical/optical, and magnetic. The boundaries between these categoriesare by no means fixed or discrete, however, and manyinteresting and useful phenomena lie at the intersections oftwo or more categories.In this chapter the focus is on general aspects of materialsbehaviour, in contrast with what has been presented in chapters1 and 2 where the various contributions have beendevoted to specific types (classes) of materials. Furthermore,concentration on materials phenomena implies payingattention to fundamental scientific issues. The technologyneeded to exploit a certain phenomenon does not belong tothe core of the discussion here. Yet, various contributions inthis chapter depart from a more technological basis. But eventhen, the discussion should culminate in identification ofthose materials phenomena that deserve our special interest.The properties of a substance are intimately related to itsstructure and the interactions between its building units.Thus, to understand material behaviour it is imperative toIntroductionknow the atomic and electronic structure. Few materials areused solely in their ideal equlibrium state. Non-equlibriumphases can be associated with exceptional phenomena thatcan make the material amenable to practical applications,e.g., doped semiconductors, or metallic glasses.It is not at all enough to describe the ideal arrangements ofatoms for materials: real materials exhibit properties that areto a large extent determined by non-idealities, as grain boundariesand surfaces and defects in the atomic arrangement.The quantitative description of material properties is verycomplex, because many length scales have to be considered.Understanding the intrinsic imperfections in the structureof materials and developing models for predicting materialproperties from atomic to macroscopic scale are cardinal topicsof research in materials science.The basis of any understanding of materials behaviour mustbe knowledge of the equilibrium constitution: which phases(composition and amount) are present. In principle adescription can be provided of the state the system underconsideration strives for, including the possible identificationof metastable intermediate stages and the net amount ofenergy gained (or to be delivered). In spite of its long history,important aspects of the theory of material thermodynamicsare under development and deserve attention urgently.Parameters as temperature and atmosphere affect the occurrenceand magnitude of a given phenomenon. For example,a strong magnet at room temperature will become an ordinaryparamagnetic material if heated above its Curie point,▲Transmission polarized light micrograph of a MoO 2 particle (U. Täffner,MPI für Metallforschung Stuttgart)

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART152and platinum catalysts are rapidly “poisoned” by carbonmonoxide gas. Phenomena such as creep, crack propagationand oxidation can be detrimental to materials performance.Hence, what happens to a material once it is in use is anessential aspect of materials science.The existing theoretical knowledge of the kinetics of materialbehaviour is very incomplete. There are various reasonsfor this observation. For example, to couple the driving force(i.e. gain in net energy) directly to a mobility is difficult and anumber of important questions can be derived from this conclusion.Further, although many kinetic measurements havebeen reported for a myriad of systems, a severe lack exists ofsignificant kinetic data obtained from suitable model systemsthat allow generalization. If we don’t improve greatly ourunderstanding of kinetics, there is no chance that we will beable to control the microstructure of materials by means ofwhich the properties of products can be influenced dramatically.With a view to the past it can be said that current activities inmaterials science have been revolutionized by the emergenceof small scale systems (e.g. thin films, nanomaterials). Theultimate form of nanotechnology, the handling of singleatoms, has become feasible and gives rise to the discovery ofnew phenomena. Thereby, certain problems in the “classical”areas of research have got an immediate urgency (role ofinterfaces and surfaces, stress, etc.). It can be seen from thecontributions contained in this chapter that this statement isa recurring theme for much of what is presented.The contributions in this chapter discuss different aspectsof materials phenomena, such as thermochemistry, nanoscaleeffects, electronic, magnetic and mechanical properties.It is not possible to be complete; the items discussedwere chosen hoping that the reader will gain an appreciationfor the great diversity of the phenomena exhibited by all kindsof materials.Specific types of materials have not been mentioned untilnow in this introduction, recognizing the striving for discoveryand understanding general, fundamental laws governingmaterials behaviour. Yet, it goes without saying that certainphenomena are associated with specific material classes andstates of matter; see contributions devoted to metals,polymers, colloids, etc. Currently a focal point of interestdevelops around biomaterials and, for example, the interfacebetween biomaterials and inorganic materials appears a richsource of topics for exciting research.

5.1. Thermochemistry of MaterialsF. Aldinger | Max-Planck-Institut für Metallforschung, 70569 Stuttgart, GermanyJ. Ågren | Royal Institute of Technology, 10044 Stockholm, SwedenR. Ferro | Universitá di Genova, 16146 Genova, ItalyG. Effenberg | Materials Science International Services GmbH, 70507 Stuttgart, Germany5.1.1. IntroductionThe development of new materials is traditionally a verytedious process involving extensive experimental investigationsby which composition and processing conditionsare varied in a more or less erratic manner until thedesired properties are achieved.The properties of materials depend on phases present,their composition and how they are geometricallyarranged in the microstructure involving structuralelements on micro, nano and atomic scale. Therefore, adetailed information about temperature and compositionstability ranges of the different phases and their transformationsand equilibria as well as eventually occurringnon-equilibria states are indeed indispensable for a fullunderstanding of the properties and possible applicationsof a given material. This is true equally for metallic andceramic alloys as well as for polymer blends.On the one hand the potential of new engineering materialsexceeds by number of possible element combinationsall experimental research capacities. On the otherhand the already existing data, i.e. the starting base forfuture research is very huge, scattered, conflicting andincreasing by about 20% every year. A considerable amountof resources and time has to go into the evaluation of thesedata for each project before controlled steps can be setinto the “terra incognita” of possibly coexisting phaseconfigurations, microstructures and properties. Thisincreasingly slows down the overall research efficiency.Reality is that in each of the European countries theintellectual resources, laboratories and people working inthis field are sub-critical, whereas Japan has implementedyears ago a lasting national programme, RACE, whichalso covers the generation and accumulation of materialschemistry data.For Europe it is required to establish “Knowledge buildingStructures”, with participation of the remainingcentres and the active Europe-based Communities whichhave taken the initiative in their hands.For many simple alloys and blends a large amount of constitutionalinformation is to be found in data-bases andreference books although frequent revisions and re-assessmentsare needed. If critically evaluated, such constitutionaland thermodynamic data develop predictive power,when appropriate thermodynamic calculation softwareand model descriptions are applied. Even though suchmainly binary and ternary phase diagrams outlined in comprehensivecompilations have guided the engineers, theirquantitative value is limited because most materials ofinterest contain many more components and the relevantphase diagrams thus are multi-component.While considering the science and technology of alloysand blends one has to insist on the fact that assessment,evaluation (possibly also prediction) of multi-componentphase diagrams should be one of the first steps, to be followedby (or combined with) the evaluation of kinetic dataand the investigation of functional properties in the definitionboth of alloy and blend applications and their stability,synthesis, processing, etc. It is well known, that to thiseffect, reliable constitutional data should be available forthe sub-system of the multi-component alloy system underconsideration: in particular well assessed data concerningthe underlying binary sub-systems and some characteristiccompositions of the ternary sub-systems are certainlyneeded. Thermodynamic data are therefore of particularinterest. There is a need of reliable thermodynamic data inthe evaluation of oxidation, reduction processes, combustion-synthesismethods and in mixing/demixing of polymer-basedsystems, to name just a few. It should be notedthat almost all industrial branches could benefit from reliabledata and application skills in materials chemistry.MATERIALS PHENOMENA153It is well possible to recover in a concerted action the lostcompetence of Europe. Simple networking with exchangeof people only can no more turn the situation.Experimental thermo-chemistry of alloys has a long fruitfulhistory, but not only in view of the requirements of itsapplications, but also for several intrinsic reasons as instrumentation,intercalibration, standardization, systematiccollection of data consistency of data, etc. It cannot

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART154be considered to be at all a mature level. The same holdstrue for polymer blends and macromolecular microphaseseparatedsystems.The materials interesting in view of new applications aregenerally based on multi-component systems. Since acomplete experimental mapping of such multi-component,i.e. multi-dimensional phase diagram is out of question,computational phase studies known as CALPHAD(Calculation of Phase Diagrams) method are of increasingimportance. It offers a very efficient use of the availableexperimental data and allows accurate estimates of phaseequilibrium relationships and thermodynamic propertiesfrom a limited set of experimental data.This means a winning strategy in the investigation of suchmaterials should be based on the coupling of selected highquality experimental measurements of thermodynamicproperties with the computational optimization of phasediagrams.5.1.2. Evaluation of Constitutional DataA concerted European effort, in which intellectual evaluationof data, targeted experimental and computationalphase studies are supported by a modern information technologyseems to be the right approach to improve theEuropean position.With the above figures in mind it is mandatory to have allpublished information available and to convert the oftenconflicting data into reliable knowledge. Here, Europe hasalso a long standing tradition and could rely on MSIT, theEurope based “Materials Science International Team”.MSIT is running the world’s largest phase diagram evaluationprogrammes with applied standardization and qualitycontrol for 16 years. To make the advanced electronic informationsystem, review and publication structures of thisteam useful in general seems to be a convincing contributionto improve the European research infrastructure.5.1.3. Experimental ThermodynamicsAn indication of the state of the art in materials thermodynamicsmay be obtained by considering periodical meetingsentitled “Thermodynamics of Alloys” which are organizedsince 1983 every two years by European laboratoriesactive in this subject. The first one was held in Stuttgart,followed by other centres of excellence in this field, asVienna, Barcelona, Nancy, Genova, Marseille, Kiel andStockholm. Generally, mainly European laboratories participatedbut a few delegates from high-level laboratoriesfrom the U.S. and Japan were also present.In these meetings several hundred communications werepresented and discussed. This number is relatively small,as profound experimental work takes time. The increasingpower of computational thermochemistry makes the supplyof accurate experimental data the limiting factor insearching the large potential of unexamined element combinations.Still numerous experimental difficulties are experiencedleaving serious problems in the evaluation andthe assessment of data. As a consequence, reliable data,which would be needed for a sound unambiguous definitionof the phase equilibria and for a good design of processes,are often lacking.It can be concluded that in the long history of experimentalthermodynamics of alloys, several hundred instrumentsand methods have been invented, designed and set up inorder to determine characteristic temperatures and thermodynamicdata. Many papers have been published suggestingand discussing the characteristics of hard (and soft)ware employed in self-made and commercial instrumentsfor data acquisition and elaboration. These instrumentsand techniques followed and replaced each other apparently,however, without reaching a full technological andmethodological final level.For a certain number of alloy systems (roughly one in everyten binary systems for which a phase diagram has beenproposed, a few ternary ones and very few higher componentsystems) thermodynamic data have been reported.In a very few cases only a complete set of thermodynamicfunctions (heat capacity, entropy data, formations functions)have been experimentally determined. Although,in a selected number of cases a good reliability may beassigned to the reported data. In most cases this is not true.Heats of formations, for instance, determined for certaininter-metallic compounds by different calorimetric methodsin different laboratories very seldom differ from eachother by less than 8-10%. Much higher is, on the otherhand, the uncertainty and the inconsistency between thevalues of enthalpy of formation obtained from calorimetryand other methods used for their estimation. As a conclusionit has to be underlined that (due to the great experimentaldifficulties) there are very few systems for which acomplete set of accurate thermodynamic functions is availableand can be safely used for subsequent calculationsand extrapolations. This is crucial, since all kinds of productionof materials, their thermo-mechanical treatment,joining, and their performance in service etc. are controlled

y these functions. If they are not known, the reliability ofprocesses, components and systems will be substantiallyreduced. And solid modelling and simulation of productionprocesses, materials structure and property evaluations,which are driving forces for modern technologydevelopment, can hardly be performed.5.1.4 . Computational Phase StudiesIn computational phase studies, the Gibbs energy isexpressed as a function of temperature, pressure and phasecomposition for each individual phase in a system includingeffects of molecular weights and molecular weightdistributions in polymer-based systems The mathematicaldescription of phases ranges from the simplest analyticalexpressions given by regular solution theory, to very complexexpressions for phases with several sublattices as wellas molecular species, ions and magnetic interactions. Theparameters in the expressions are adjusted to quantities thatmay be derived from the Gibbs energy are fitted to thecorresponding experimental data. For example, in a pureelement the liquid and the solid phases have the same valueof the Gibbs energy at the melting point, the first derivativeof the Gibbs energy of a phase with respect to pressure isequal to the volume of the phase etc. The basic idea of theCALPHAD method thus is two fold: it yields a consistencycheck of experimental data and it offers a scientificallysound method of interpolating and extrapolating the data.The fundamental thermodynamic treatment of pureelements and substances and the modelling of solutionphases have been treated during several international workshopsat Ringberg castle in recent years supported by theMax Planck Society. Additionally, the use of computationalthermodynamics, especially the CALPHAD approach, forcommercial applications was discussed. The general scopewas to provide recommendations and guidelines for thedevelopment of consistent and compatible high quality andinternationally accepted thermodynamic databases. Both,metallic and ceramic materials were treated to test availableand new developed multi-component data sets. However,although there is much progress in the thermodynamicmodelling, there still remains a lot to be done in order touse this tool for the systematic evaluation of the thermodynamictreatment of materials development process.Several Windows-based software packages that allowcalculation of phase equilibria and phase diagrams as wellas other thermodynamic quantities are now commerciallyavailable. Calculations considered as cutting edge a fewyears ago may now be performed on a routine basis bypersonnel without much expertise in thermodynamicsor computations. Nevertheless, such calculations are nobetter than the databases used and if no data is availablefor a particular material then no calculations at all can beperformed despite the capability of the software.Therefore, what is outlined in Sect. 5.1.1 is also relevantfor computational phase studies. However, a consequentapplication of computation will be a valuable tool forthe planning of defined experimental investigations thusreducing efforts and costs.Fortunately, good databases are available for some importantclasses of materials as steels, superalloys and aluminiumalloys. These databases cover composition andtemperature ranges of industrial interest and their shortcomingsare usually well known and subject for furtherdevelopment. For most other classes of materials or compositionsfar outside the conventional range the situationis much less satisfactory and a large research effort is stillneeded. This is the case still for many metal alloys butcertainly for most of ceramics and polymers and even sometypes of high-alloy steels. It is unfortunate that it is sodifficult to obtain funding for such research. The researchefforts need to be directed towards experimental determinationof thermochemical properties, e.g. enthalpy offormation of compounds and solutions, activities andphase equilibrium data. The data need to be carefullyassessed taking information from all available sources intoaccount and finally represented as Gibbs energy functionsthat are stored in databases.Another approach to achieve data is by ab initio computations.Such computations are based on a quantummechanical analysis of the system and make only use ofinformation that can be found in the periodic table, i.e. noadjustable parameters are introduced. Over the years thecomputational techniques have been refined and nowadayscalculations can often be made with satisfactoryaccuracy. For example, one may mention calculations ofenergies not only of pure elements in different crystallinestructures but also of compounds and alloys as well asenergies of interfaces and surfaces. A drawback is that thecalculations are performed at 0 K but nevertheless theresults are much valuable. In principle, the calculationsgive the elastic properties at 0 K and it is then possible tointroduce the effect of lattice vibrations and extrapolatethe results to higher temperatures. It is expected duringthe next few years, that these types of calculations aremuch more common and fruitfully applicable to realsystems. In this view a concerted ab initio and CALPHADstyleapproach, based on new selected experimental data,has been proposed and should be encouraged.MATERIALS PHENOMENA155

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART1565.1.5. Evaluation of Microstructure of MaterialsThermodynamic calculations are often criticized becausethey yield information only on equilibrium properties,whereas during processing and use of materials the internalreactions, by which equilibrium is approached, arenot fast enough to allow full equilibration. This criticismis not always justified. For example, in many cases the situationmay be approximated as close to equilibrium withrespect to composition and relative amounts of the differentphases although a very slow coarsening process maystill take place. If certain phases are known to form slowlydue to kinetic barriers, a reasonable result may still beobtained by simply excluding these phases from the computation.A metastable equilibrium is thus calculated. Aninteresting application of large practical interest thatrequires equilibrium data only, is the Scheil simulation.In this simulation the amount of solid phases is predictedas a function of temperature upon solidification of a melt.At each temperature the composition of the solid layerformed at that temperature is obtained as well as the compositionof the residual liquid. The liquid is assumed asbeing homogeneous at each instant and the compositionof each part of the solid remains the same as when thatpart was formed. For many substitutional alloys this is areasonable approximation because diffusion in the solidis slow whereas the composition of the liquid should bealmost homogeneous due to rapid diffusion and convection.The Scheil simulation makes use of equilibriumcalculations only but is able to make valuable predictionson non-equilibrium states.A more ambitious approach is to combine the thermodynamiccalculations with kinetic models, e.g. diffusioncalculations, and thereby predict the rate of reactions. Thisapproach is extremely powerful and may be used in futureto simulate a wide range of different phenomena, includingprecipitation, homogenization, diffusional interactionsbetween substrate and coating etc.It is usually assumed that thermodynamic equilibriumholds locally at the migrating phase between two phasesand the rate of transformation is calculated at each instantby solving a set of flux-balance equations. The fluxes areobtained from a numerical solution of the multicomponentdiffusion equations.So far, most of the calculations on realistic multicomponentsystems have been made using so-called sharp interfacemodels, i.e. the interface between the two phases isconsidered as mathematically sharp. This approach hasbeen very successful in predicting growth or shrinkage ofprecipitates as long as the geometry is simple enough.However, in this type of calculations the geometry of theparticles, i.e. their morphology, is not predicted a priori butrather imposed by the specific model used. The phasefieldapproach, which has been developed over the lastdecade, is based on the diffuse interface concept, i.e. thephase interface has a finite width and the properties varygradually from one phase to the other. These materialsproperties have not been very realistic; usually binary alloysand ideal solution behaviour have been considered.Nevertheless, the phase-field method is capable of treatingmulti-component alloys with realistic thermodynamicand kinetic properties and it is straight forward to takeanisotropy, elastic stresses etc. into account as long asthe computational work can be afforded. In the future it isexpected to see simulations where the evolution of microstructureof multicomponent alloys is predicted for variousprocessing and usage conditions.From the above section it is obvious that high-quality databasesare needed also for kinetic properties, e.g. diffusivities,in order to make accurate simulations. In an alloysystem with n components (n-1) 2 diffusion coefficients areneeded to give a full description of how the concentrationprofiles evolve in time. A complete description of thediffusion behaviour, i.e. including the Kirkendall effect,requires diffusion coefficients that depend on temperatureand composition. The evolution of the concentrationprofile in a binary diffusion couple may thus be predictedby means of one diffusion coefficient only but already for aternary alloy 4 diffusion coefficients are needed. The numberof diffusion coefficients thus becomes very large inmulticomponent alloys and a full experimental mapping isout of question. It is necessary to assess experimentalinformation in a more efficient way that allows the resultsto be readily extrapolated and applied to new materials.This is possible because the various diffusion coefficientsare related to the individual atomic mobilities and thethermodynamic properties. As there are only n mobilitiesin an alloy with n components it is more efficient to storemobilities rather than diffusivities in a database. Themobilities may be represented by mathematical expressionsderived from models of the diffusion process and theparameters in the models may be adjusted until the modelis capable of representing the experimental data. Thisapproach, thus, is very similar to the CALPHAD approachfor handling the thermodynamic properties and should infact be regarded as a natural extension of the CALPHADmethod. Over the last couple of years several assessmentsof mobilities along these lines have been presented.

5.1.6. Future Visions and DevelopmentsA future joint, high quality aimed experimental researcheffort will be related to a powerful information platform.With a content (or knowledge) driven research and sucha information-platform available as administrative tool itshould be possible to link different data bases and toco-ordinate competence from different centres, as theyare needed in1. experimental thermodynamics and constitutionalresearch,2. computational thermodynamics and kinetics,3. intellectual evaluation of data and diagrams,4. property measurements and analytics.These methods normally have to be applied several timesin each study. Which method will disclose most of thematerials characteristics next, depends totally on the typeof material and the state of knowledge achieved.This research infrastructure could be used to train industrialengineers or Post Docs how to apply materials chemistrymost efficiently in targeted materials development, asthe “MSIT Training Network on Materials Constitution”successfully did under the former Human Capital andMobility Programme.The same research infrastructure could also be used toclarify and generate data for important categories of alloys,relevant to European industry, as the European ActionCost 507 successfully did for the light metal industries.A joint co-ordinated European effort is highly needed forinstance for a systematic programme of:1. intercalibration of data obtained with the same experimentalmethod in different laboratories,2. intercalibration of data obtained with different experimentalmethods, and3. check on the basis of phase equilibria calculations, ofthe internal consistency of all the experimental data ofbinary, ternary alloys of selected multicomponentsystems.Parallel measurements carried out in different laboratorieswith the same (or different methods) on the same samplesshould be promoted. Joint decisions about the bestinstruments and methods to be used and the selection ofsystems to be evaluated and studied should also be encouraged.A continuous comparison and critical intercalibrationof the techniques and of the results is necessary.It has been underlined that an improvement of the methodsand of the instruments, and especially a better standardizationof the techniques and the systematic use of, asmany as possible, auxiliary analytical techniques would bevery useful. Of special interest could be the design and developmentsof instruments which, with the necessary facilities,could work in different laboratories and routinelyat high temperatures.High temperature, thermal and thermodynamic measurementscould be very conveniently inserted in a widersystem of high temperature researches, including for instancehigh temperature microscopy, high temperaturediffractometry, etc. Very interesting (not only for equilibriabut also for kinetic investigations) could be the combinationof high temperature techniques with the use of highintensity (synchrotron) X-ray sources for diffractometry.5.1.7. Needs and RecommendationsLaboratories dedicated to the above topics do exist inEurope, their level is generally high. The interconnectionbetween the different groups proved to be successful onmany occasions, too. Experience in content managementand in running large scale materials science teams are athand as well. The creation and diffusion of information,however, may be largely improved.What seems to be missing is strict co-operation, all yearround, remotely and by personnel exchange; a co-operationwhich is to be validated by the increment of reliable,applicable knowledge.What seems to be lacking in Europe is a continuous modernizationof instrumentation, and a close co-operationincluding personnel exchange.It is therefore highly desirable to create a European institutionwith the responsibility and authorization to suggestand coordinate research in materials chemistry. The chairor presidentship of such an institute could be assigned inturns to the partner institutions active in this materialsnetwork. Students and researchers exchange betweenall the laboratories involved should be promoted as wellas periodic meetings for the exchange of information,samples, planning of future researches, etc.MATERIALS PHENOMENA157

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGARTIn any case it would be vitally important that the materialscience community in Europe can make use of an electronicsteering and communication system1. that gives access to present, past and future data inmaterials chemistry,2. that monitors progress in and outside Europe,3. that can host and interconnect different databaseswhich remain under the responsibility of the creatinglaboratories,4. that reports on ongoing work elsewhere,5. that serves as an editing tool for joint documentationand publishing.The system should be platform independent for easymigration to different computer systems and should bepermanently maintain data integrity and availability. Mostattention has to be given to the management of such asystem, as this is the interface between humans and anelectronic network.1585.2. Phase TransformationsE.J. Mittemeijer and F. Sommer | Max-Planck-Institut für Metallforschung, 70174 Stuttgart, GermanyContributors:J.M. Howe (University of Virginia, Charlottesville, UnitedStates) and F. Spaepen (Harvard University, Boston, UnitedStates).5.2.1. IntroductionThe specific properties of materials, and thereby the performanceof workpieces in practice, are largely determinednot only by the intrinsic properties of the materials but to avery large extent by their microstructure. A classical exampleis steel, where only after dedicated heat treatments,bringing about complicated phase transformations, thespecific, looked for (mechanical) performance is achieved.Understanding and control of phase transformations ingeneral is a prerequisite to optimize the microstructurewith respect to the desired properties not only phase transformationsin the bulk are important. Hence it is imperativeto have knowledge of the thermodynamics and kineticsof phase transformations in the bulk and at interfacesand surfaces.5.2.2. State of the ArtExperimental techniques to observe the microstructureare available for the interesting length scale (1 Å to 1µm).Further, a wide range of techniques and facilities are availableto study Solid-Gas, Solid-Liquid and Solid-Solid (S/V,S/L, S/S) inter-phase reactions under ultrahigh vacuum orcontrolled environmental conditions. Sophisticated characterizationfacilities allow to quantify the structure andproperties of S/V, S/L and S/S interfaces at the atomic andelectronic levels, e.g. field-emission high-resolution transmissionmicroscopes and various scanning probe microscopes.A detailed theoretical framework for quantifying the structure,mechanisms, kinetics and thermodynamics of S/V,S/L and S/S reactions, both on microscopic (phenomenological)and atomic levels has been worked out.A significant amount of atomistic, thermodynamic andkinetic data are available for modelling phase-transformationphenomena to compare between theory and experiment,particularly in the case of metal alloys of componentswith face-centred cubic lattice e.g., Cu, Ag and Au.5.2.3. Trends and Expected Needs(a) MaterialsMaterials such as ceramics, intermetallics, semiconductorsand polymers have growing impact in today’s researchactivities because of their increasing potential for technologicalapplications, relative to metals.(b) DataMore basic thermodynamic data of the multicomponentmaterials, such as enthalpies, free energies of formation,heat capacities, interfacial energies and phase diagrams,

are needed, at least as a function of composition and temperature.Data of thermophysical properties like diffusivityand viscosity are further required to understand and tomodel inter-phase reactions. The data should be evaluatedand easily be accessible. This requires hard work, whichis often not appreciated within the scientific community.(c) Knowledge• NucleationQuantitative prediction of nucleation is the hardest problemin the modelling of interphase reactions. The problemhas several aspects. Experimentally, the phenomenon isstochastic and is usually heterogeneous (i.e. catalysed by,often unknown, impurities). The main theoretical difficultyis the calculation of the work necessary to form acritical nucleus. The principal unknown here is the energyof the interface between nucleus and matrix. Determiningthis energy is particularly difficult in the case of nucleationfrom a liquid, since the interface is difficult to accessexperimentally, and modelling of its structure and thermodynamicproperties is complex.• Interface and Surface EnergiesSurface and interface energies play an important role, forexample recognizing the increasing importance in smallscale structures. Unusual (as compared to bulk materials)phenomena can be observed: favourable interface and surfaceenergies can stabilize amorphous phases or, generally,phases that would be unstable as bulk material. Therebyexciting new electric, magnetic and mechanical propertiesbecome accessible for practical applications. The thermodynamicsfor such systems need to be developed, becauseat the moment only at best semi-empirical approaches (e.g.on basis of the Miedema approach) are available.• KineticsReactions at surfaces and interfaces and within the bulkare decisive for the resulting properties of materials. Oneof the great challenges is to find the relation between thethermodynamics (driving force) and the kinetics of thesolid-solid, solid-liquid or solid-gas reactions/phase transformationsinvolved. At the moment at best rather badfounded, descriptive, fit functions are used, e.g. the Johnson-Mehl-Avramifunction. This should be a main field offuture activity.• Structure of and Reactions at Grain Boundaries,Interfaces and SurfacesIn general, improving our knowledge of the structure, segregationbehaviour, mobility and thermodynamics of interfaces,both in equilibrium and in the undercooled or supersaturatedstates, is essential to progress in the modelling ofinter-phase reactions. It is imperative to know more abouthow the properties vary across inner interfaces of a singlephase and interfaces between different types phases.Some very fundamental questions related to the mechanismsof phase transformations are unsolved, e.g. themechanism of grain-boundary motion and its relationshipto the so-called grain-boundary mobility and its dependenceon the grain-size distribution are not even knownfor pure metals. The role of impurities (segregants) duringthe processing of materials and the mechanismsby which they affect the resulting material properties arenot well understood.Catalysis of reactions at surfaces is of great technologicalimportance. Catalysts represent a widely utilised class offunctional materials where the structure over the wholelength scale, from the atomic arrangement to the microstructure,has to be optimized. Each catalysed reactionexhibits many elementary steps from which one step (thereaction-rate determining step) is not in equilibrium. Thecatalyst works on this elementary step to modify the overallreaction rate. This step is (usually) not known and maychange for the same reaction under different externalconditions.• Structure of Liquids and GlassesFinding a paradigm for the structure of simple liquids thatis as simple and compelling as the “periodicity” is forcrystals or the “diluteness” for gases remains one of theforemost challenges in science. The concept of “polytetrahedrality”,which captures the essential short-range order,comes closest, but even its most advanced formulationonly involves a limited number of atoms. Metallic glasses,even though they are alloys, are structurally most closelyrelated to simple liquids. The recently discovered bulkmetallic glasses, which can be obtained at low cooling ratesand held above their glass transition temperature withoutrapid crystallization provide unique opportunities for thestudy of the glassy state. Inorganic glasses are of considerableinterest. For example, detailed structural knowledgeof the 2 nm thick silicon-oxynitride glass layer foundbetween sintered nitride grains is essential for creatinga predictive model for the sintering process.(d) Materials in small dimensionsMaterial systems continue to decrease in size. This developmentis in particular driven by the developments in themicroelectronic industry and by the application of surfacemodifications. The focus on small scale structures, whichcan be well illustrated by the ever growing importance ofthin film structures, highlights a strong need to understandthe fundamental relations between the structure and theproperties of materials: extreme control on a very local,MATERIALS PHENOMENA159

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART160small scale becomes imperative from an engineering pointof view, but in particular also from a fundamental scientificpoint of view, as the properties of small scale materialscan deviate strikingly from those of bulk materials. By studyingthe properties of small scale structures new, fundamentalinsight into the physics and chemistry of solids isacquired.Small scale structures, as thin films, are invariably andusually severely stressed. A strongly growing interest in therole of such stresses exists. This is partly caused by practicalaspects (as the undesired detachment of a thin layer),but especially also by the associated fundamental aspects:• The (driving force for) diffusion in small scale structurescan be affected strongly by such (nonhydrostatic) stresses,as also holds for the process of electromigration. Thisis an area of strongly deviating opinions and results. Itwould be very rewarding if such work would be promoted.• The thermodynamics and kinetics of phase transformationsin a state of stress are hardly understood. Muchwork is needed in this area, in order to master small scalestructures.(e) Computational materials science; bridging the lengthscalesIn recent years the role of computer simulations to modelphase transformations has gained more and more importance.The reason is that is is impossible to arrive on thebasis of first principles for the atomic mobility at predictionsfor the behaviour of an aggregate composed of manycrystals. Thus, for example, Monte-Carlo type of approachescan be applied to model solidification (see Fig. 5.1).Multiscale calculations in time (picoseconds to seconds)and length (atomistic to micrometres) are important in ahierarchical modelling from atomic processes to phenomenologicalmodelling of e.g. phase equilibria and microstructuredevelopment. The task is to find the connectionbetween discrete (atomistic) models and continuous models.This is a topic of extreme importance in MaterialsScience. Recognizing that it is impossible to arrive at an abinitio determination of materials behaviour, one realizesthat this area of mesoscopical materials science bears greatpromise, as it appears to be the appropriate and alsofeasible route to model, for example, the mechanicalbehaviour of a thin film due to the collective response ofall dislocations in the film to some external action. To thisend in particular computer simulations and experimentson small scale structures are necessary.5.2.4. Differences in Trends and Needs between Europeand the Rest of the World (U.S. and Japan)The overall expected trends in basic materials research aresimilar in Europe, the U.S. and Japan. Research on all typesof materials will continue to increase, requiring a comprehensiveunderstanding of inter-phase reactions in thesematerials. The need for materials scientists to understandand deal with all types of materials will therefore increaseas well.Equipment which is able to sense and respond to processingconditions will be needed to control S/V, S/L and S/Sreactions to extremely accurate level in order to reliablyproduce nano-scale structures. Investment in technicalexpertise, the development of sophisticated novel equipmentand systems is needed to accomplish this goal.The educational system in Europe is highly competitivewith the rest of the world, including U.S. and Japan. Thereare, however, many more material science departmentsin the U.S. than in Europe and these perform much of thefundamental materials research, in addition to researchin national laboratories.a) b)Europe has a better technical base, i.e., many more highlytrained technicians, for supporting basic materials researchthan countries such as the U.S. and Japan. This isextremely valuable to fundamental research and it shouldbe continued.Fig. 5.1. Computer simulation of the effect of surface rearrangement on themorphology of the eutectic solidification structure. No surface rearrangementis allowed in (a), while (b) presents the structure developed witha certain value for the surface diffusion-length parameter. Inset showsmagnified view of the solid(top)-liquid(bottom) interface.

5.2.5. Current Competitiveness of EuropeEurope is competitive with the U.S. both technically and academically.This is true although the amount of fundamentalresearch in some areas such as S/S reactions decreaseddramatically for a number of years in Europe. To a certainextend this has also occurred in the past ten years in the U.S.,while the opposite has happened in Japan. As a result, Japanis leading the world in a number of areas of materials properties,in terms of both manpower and facilities.5.2.6. RecommendationsThe EU should actively seek to prevent the erosion of fundamentalmaterials research on interphase reactions in theareas described in the above section “Trends, expectedneeds”, in order to maintain international scientific andtechnological competitiveness. Technology constantlychanges, often in unpredictable ways; it can be very detrimentalto the natural progression of fundamental knowledgeif it is made to follow technology to closely.There will be a continuous need for investment in stateof-the-artfacilities such as sophisticated equipment forfabricating materials, (micro)structure analysis, and computation,etc. Trained personal to maintain and operatethe equipment is a prerequisite for successful research inmaterials science. The state-of-the-art equipment is costly,but it is absolutely essential to remain competitive inscience, access to such facilities is a must. It may proveboth financially and scientifically beneficial, to establishshared research facilities for major equipment and to provideappropriate travel funds and infrastructure to facilitatetheir use by scientists in the EU.Many common phenomena are involved in S/V, S/L andS/S reactions. However, the different scientific communitieswhich study interface reactions often do not communicateand co-operate. It would be useful to establish astrong network of multinational research centres in the areasof materials science that are considered most urgent(e.g. the field of “materials in small dimensions”; seeabove), where researchers would investigate and exchangeinformation on their progress. Such centres would includeboth experimental and theoretical groups. These centreswould provide more permanent research opportunities forPh.D. students and post-graduated materials scientists.References1. Proceedings of the International Conference on Solid-Solid Phase Transformations‘99, M. Koiwa, K. Otsuka, T. Miyazaki (Eds.), The Japan Instituteof Metals, 1999.MATERIALS PHENOMENA1615.3. Interface ScienceR. C. Pond | University of Liverpool, Liverpool L69 3BX, United Kingdom5.3.1. IntroductionThe goal of Interface Science is to facilitate the manufactureof technological materials with optimized propertieson the basis of a comprehensive understanding of the atomicstructure of interfaces and their resulting influence onmaterial processes. Of course, establishing such a completeunderstanding would be a monumental undertaking.Consider the parameters which govern interface structureand behaviour; besides the crystallographic and compositionalvariables which define a polycrystalline system, theexternal conditions, temperature, stress, electric/magneticfields, radiation and chemical environment, prevailinghistorically and currently need to be taken into account. Apolycrystal may respond to such external disturbances byinhomogeneously activating a multiplicity of processes,and consequently the interpretation of experimentalobservations and theoretical modelling may be correspondinglychallenging. In a short article it is not feasible toreview the ‘state of the art’ of interface science in depth,and the reader is referred to the outstanding text by Suttonand Balluffi [1] for a fuller account. In section 2 we outlinethe crystallographic and thermodynamic foundationwhich has been established in this field before highlightingthe most prominent experimental techniques and somefindings from modelling. Subsequently, a representativeillustration of the current position in Interface Science isaddressed through a case study of interface mobility in

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART162metallic materials. Section 3 describes recent trends inresearch activity and future developments that wouldassist progress. Finally, in section 4, we briefly comparethe competitiveness of Europe versus the U.S. and Japan.5.3.2. Current Position(a) Crystallographic and thermodynamic foundationA rigorous crystallographic and thermodynamic foundationis essential for effective communication within themultidisciplinary international community. Following contributionsfrom many researchers, this has been established,and is set out in reference [1] for example. Thespacegroup symmetry of any candidate bicrystal (or tricrystaletc.) can be classified in a scheme which takes intoaccount the spacegroups and relative orientation of theadjacent crystals, the orientation of the interface plane,the relative position of the crystals and local atomic displacements.This classification scheme applies to heterophaseand homophase boundaries, and colour symmetryhas been found to be useful in the latter case. It is conceivablethat non-classical symmetry groups, as observed inquasicrystals, could be relevant to interfacial problems,but this possibility has not been developed beyond basicnotions so far.Thermodynamic considerations of interfaces are based onthe method introduced by Gibbs, and the reader is referredto reference [1] for a concise review of the subsequentdevelopments in phenomenological and statisticalmechanicsapproaches. According to Gibbs, interfaces arenot thermodynamically autonomous regions, i.e. shouldnot be viewed as independent phases existing in equilibriumwith surrounding material. Instead, their influence onpolycrystals is treated as a perturbation of the system andis expressed in terms of excess thermodynamic quantities.This formulation emphasises the complex interactions thatmay occur between material at the interfacial region andin the bulk of the adjacent crystals. For example, impuritiesmay segregate to an interface at lower temperatures,and desegregate at higher ones. In general, the contributionof the excess free-energy due to the presence of interfacesto the total free energy of a polycrystalline aggregatedepends on all of the internal degrees of freedom of thesystem and the environmental conditions mentionedabove. Moreover, its significance may change as a microstructureevolves during manufacture or service. For example,the magnitude of interfacial energy may be a keyparameter in the nucleation stage of a new phase, but maybe dominated by other factors such as strain energy atlater stages of growth.(b) Experimental techniquesA wide range of physical techniques has been employed inInterface Science. Interfaces, being buried structures, areinevitably more problematic to investigate than free surfaces.Nevertheless, much valuable information has beengained by microscopical studies of surfaces. For example,scanning electron microscopy (SEM) has been adapted tostudy mechanical phenomena such as relative grain motionsin polycrystals, electrical features like carrier depletionregions, and chemical concentrations in the vicinityof interfaces. In principle, interfacial excess free energies,relative to some reference, could be found from studies ofthermal grooving, but only pilot studies have been reportedso far. A major recent development has been the automateduse of electron back-scatter diffraction (EBSD)which enables phase identification and grain orientationdetermination. Instruments are being developed whichenable textural information to be gathered simultaneouslywith in situ heating and deformation. Two other techniquesthat provide valuable chemical information, X-ray photoelectronand Auger spectroscopy, are applied toexposed surfaces following intergranular fracture inducedin high vacuum. The performance of the atom-probe fieldionmicroscope has continued to be refined, and is capableof revealing structural and chemical information at theatomic level by sequential removal and analysis of thesurface layers of a needle-like specimen.Transmission electron microscopy (TEM) is the mosteffective technique for directly revealing the structure andchemistry of interfaces. The principal imaging modes arediffraction contrast (DC) and high-resolution (HR), andcrystallographic information can be obtained using diffraction.Chemical assessment can be carried out by analysisof emitted characteristic X-rays or electron energy lossspectroscopy (EELS). A small number of in situ studiesof interfacial processes have been published, for examplepenetration of interfaces in Al by liquid Ga, and phase transformations.Investigations using DC imaging have revealedmuch about the defect structure of interfaces, givingimpetus to the development of defect models of interfaces(see below). In addition, very precise measurements of therelative position of adjacent crystals have been made. HRimaging has elucidated the structure of interfaces in a widerange of materials, and the recent introduction of thez-contrast method enables chemical species to be differentiated.Contrast observed using DC and HR imaginggenerally needs to be interpreted by reference to computersimulations generated using the dynamical theory of electrondiffraction. A serious constraint is that HR imagingrequires the incident beam to be parallel to low indexdirections in both crystals simultaneously, and also to beparallel to the interface plane. Its application is therefore

limited to interfaces with appropriate crystallography, andcannot be used to investigate less ordered interfaces, animportant category about which our knowledge is limited.(c) ModellingTopological models of interfaces have been developed ona purely geometrical basis. The underlying notion is thatinterfaces exhibit regions where the adjacent crystals‘match’ separated by regions of ‘mismatch’. The regions ofmismatch are regarded as defects superimposed on somereference structure corresponding to the matching regions.The defect content in such interfaces can be expressedprecisely using the Frank-Bilby (F-B) equation. Initially,this equation was formulated by taking only the translationsymmetry of the adjacent crystals into account, andidentifying the total Burgers vector, b, intersected by aprobe vector lying in the interface. More recent work,based on the Principle of Symmetry Compensation, hasgeneralised the F-B equation by considering the completespace group symmetry of the two crystals [2]. Referencestructures can either be a single crystal or some nominatedbicrystal structure. The former case is valuable for describinglow-angle grain boundaries as arrays of crystal dislocationsseparated by regions of distorted single crystal.The latter case is helpful for a variety of other interfaces,especially grain boundaries which are vicinal to ‘favourable’reference structures, and misfitting epitaxial heterophaseinterfaces. Arguments using the generalized topologicalapproach have demonstrated that the range of defect typesthat are admissible in interfaces is broader than previouslyrecognised. In addition, in the case of interfacial dislocationsfor example, it has been shown that their step height,h, is a second important topological parameter besides b.Step heights can be defined rigorously, and relate to theamount of material transferred from one crystal to the otherwhen a defect moves along an interface. Thus, the magnitudeof diffusive associated with interfacial defect motionand interaction can be quantified in terms of b, h andthe density of the constituent species in the two crystals.In general, it is not anticipated that models formulatedusing geometrical parameters alone can have quantitativecapacity for predicting interfacial energies or processkinetics. Consequently, models that couple a physicalhypothesis with geometrical arguments have been proposed.A widely used example is the phenomenologicaltheory of martensite crystallography (PTMC) [3]. Thistheory predicts the displacement, habit plane and shapedeformationfor martensitic transformations. The geometricalprocedure involves identifying an invariant plane ofthe transformation, and has been justified on the groundsthat such a relationship minimizes the strain energy of aplate shaped precipitate. In general, the habit plane is irrational,and experimental observations are in good agreementwith the model for several material systems.Another model, this time for grain boundaries, is the coincidence-sitelattice (CSL) model; the original hypothesiswas that atomic occupation of coincident sites at periodicinterfaces leads to energetically favourable structures and,furthermore, that such structures exhibit distinctive properties.We now know, from TEM measurements of the relativeposition of crystals for example, that atomic occupationof coincident sites is exceptional and the propositionhas been amended to suggest that periodicity is the keyfeature. While this notion has not been definitively provedor disproved on fundamental grounds, there is definitesupporting experimental evidence in some instances.However, the general applicability of this model is not clearand is hotly debated currently, and the literature is perhapsdominated by advocates rather sceptics. Bollmannintroduced the notion of generalized coincidences, or ‘O’points. The geometrical part of this theory is equivalent tothe F-B treatment of interfacial defect content, but itincorporates the hypothesis that low interfacial energy iscorrelated with a high density of ‘O’points being located inan interface.Atomic scale modelling of interfacial structure and processesusing computer simulation techniques has providedstimulating insights; the reader is referred to Suttonand Balluffi [1] for a review of methods and achievements.Here, we indicate some examples that illustrate the conclusionsreached by considering the interactions betweenatoms. Ochs et al. considered periodic interfaces withidentical crystallography in Nb and Mo, and found thatthe spatial distributions of the conduction electrons in thenear interface region were distinctly different in the twocases. Moreover, this caused the relative positions of theadjacent crystals of the fully relaxed interfacial structuresto be different in Nb and Mo, as was confirmed experimentallyusing HR-TEM. Rittner and Seidman showedthat segregation of impurities to interfaces in metals iscomplex and is not simply correlated with geometricalparameters such as periodicity. Misfitting substitutionalspecies occupy sites in the interfacial region in a mannerdependent on the details of an interface’s displacementfield. Cottrell has discussed the strengthening of grainboundaries in Fe by segregation of interstitial C atoms thatthereby promote the formation of covalent bonds at theinterface. Furthermore, he contrasted this with the embrittlingtendency of substitutional O atoms which tend toform ionic bonds. Thomson et al. showed that the consequencesof Ga segregation to grain boundaries in Al cannotbe explained by hard-sphere arguments. Ga replacesAl at ‘tight’ interfacial sites, but in a manner which keepsMATERIALS PHENOMENA163

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART164the interface structure ‘open’, thereby enhancing diffusionand mobility. Serra et al. demonstrated that the interactionof crystal dislocations with intefaces in hcp bicrystalsunder the influence of an external stress is complex. Thedetailed structure of an interface governs whether incomingdislocations decompose into interfacial defects,become delocalised in the interface, or are transmittedthrough the interface. Fan et al. studied the variation ofgrain boundary structure in Al with increasing temperature.They concluded that the interfacial material undergoesstructural transitions; for example, at low temperatureatoms vibrate harmonically about their equilibriumpositions, but at higher temperatures atoms become mobileand more disordered interfacial structures arise. Onepoint, however, that should be recorded is that, overwhelmingly,computer modelling has been carried out on planar2-D periodic interfaces, and hence our understanding ofless orderly interfaces has not been enhanced.Multiscale modelling [4], in which microstructural evolutionor some process such as crack propagation in a polycrystalis simulated, is a valuable research tool. Remarkablecorrespondence with experimental observations hasbeen obtained in the study of precipitation in superalloysfor example. These models are based on phenomenologicalthermodynamics with order parameters and interfacialenergies included in the input data. Crack propagationstudies involve the consideration of events at the atomicscale, as well as microscopic modelling of plasticity at thecrack tip and also longer range elastic stresses and processessuch as diffusion. Deformation of polycrystals with grainsizes ranging from millimetres down to the nanoscale hasbeen studied. These works have indicated that deformationoccurs primarily at the interfaces in nanomaterials,and the Hall-Petch relationship between yield stress andgrain size breaks down. Such multiscale investigations arevery promising, but depend on our capability to identifythe key structural features and processes at each lengthscale.(d) Case study: interface mobilityInterface mobility ranges from the speed of sound, as inthe case of martensitic transformations, down to valueslower by a factor of the order 106 in processes like secondaryrecrystallization, and can be even slower in diffusionalphase transformations. This enormous range reflects thevariety of driving forces and interfacial mechanisms thatcan arise. In the martensite case, the transfer of materialacross the interface is a shear-dominant athermal processwithout diffusion and only minimal shuffling. Mechanisticmodels involving localized interfacial defects are provinghelpful in this context, and resemble those in the relatedprocess of deformation twinning. This is in contrast tograin boundary motion driven by interfacial curvaturewhich is a thermally activated stochastic process. In aseries of outstanding experiments, measurements of interfacevelocities moving under the influence of a constantdriving force have been made by Gottstein and his collaborators[5] as a function of temperature and crystallographicvariables. Atomic scale modelling using molecular dynamicshas been carried out in parallel, and close correlationwas found between experimental and simulated velocities.These studies indicate that low-angle boundaries aredistinctly less mobile than high-angle ones. Moreover, inthe high-angle regime, the researchers conclude that theactivation energies for motion of CSL boundaries are lowerthan for alternatives, and that the pre-exponential factorsare also smaller for CSL boundaries. As a consequence,the mobility of a CSL boundary may be higher or lowerthan a more general boundary, depending on the temperature.It is apparent from this example that the combinationof carefully designed experiments and parallel atomic scaleis very effective. In these experiments, a single interfacialprocess is activated at constant driving force in specimenswith known crystallography, and precise measurements ofinterface velocities are recorded. In the simulations, themotions of individual atoms across the curved interfacecan be followed, although descriptions of this stochasticprocess are difficult to summarize except using phenomenologicalthermodynamic terms. It should also benoted that the role of trace impurities was not establishedin the experiments or represented in the calculations.5.3.3. Trends and NeedsTrends in research activity in the field of Interface Scienceare stimulated by developments in experimental techniques,advances in theoretical methods, and funding policies.With regard to the latter, a balanced support of bothbasic and applied research is important. Steady progresstowards a comprehensive understanding of the influenceof interfaces on materials requires an interdisciplinary andinteractive effort by researchers addressing issues fromthe atomic to the macroscopic scales. Collaborationbetween teams and carefully planned programmes involvingexperimental and theoretical aspects are likely to beparticularly beneficial.Regarding recent trends in the development of experimentaltechniques, particular mention should be made ofthe increasingly widespread use of EBSD. Statisticallyimpressive quantities of crystallographic information canbe accumulated with precision, and correlation of this within situ studies of processes such as deformation, recrystal-

lization and stress-corrosion cracking will be valuable. Itwould also be particularly helpful if such information couldbe correlated with experimental determinations of interfacialenergies, and the role of triple junctions in polycrystalprocesses. In the field of TEM, instrumental developmentsthat will improve resolution still further are anticipated.EELS promises to advance our understanding of the electronicstructure of interfaces and phenomena such asembrittlement, but certain operational problems that currentlycomplicate the interpretation of results need to beaddressed. The technique of holographic imaging couldprovide valuable information about electric fields nearinterfaces.The topological model of interfaces is helpful for describingstructures and processes, and it is important to recognisethe capabilities and limitations this approach. Dislocationdescriptions are widely used, but there is sometimesa lack of rigour in published accounts and this has causedsome confusion. Similarly, in the reviewer’s opinion, thereis a lack of critical appraisal regarding the general applicabilityof the CSL and ‘O’ lattice models.As outlined previously, atomic-scale and multiscale computermodelling is providing valuable insights into interfaces,and they are likely to be particularly helpful infuture if carried out in support of experimental studies.Although some aspects of these calculations are sophisticated,much development is needed to progress a broaderunderstanding. For example, in the case of homophaseinterfaces, there is a need to study more disordered interfacesthat will require the use of periodic boundary conditionsin the calculations to be circumvented. To date,relatively little work has been done on interphase boundarieswhere additional theoretical challenges arise. Thesuccess of multiscale simulations depends critically onthe information input, and the identification of key structuralfeatures and processes. In this latter respect, physicalprocesses need to be expressed in a framework thatlinks different length scales. As an example, we cite thecalculation of the diffusive flux of material associated withmotion of an interfacial dislocation, as was mentionedpreviously, in a simulation of a phase transformation. Diffusivefluxes might extend over mesoscopic dimensions,but are quantified in part in terms of the microscopicparameters b and h associated with a transformationdislocation. In the context of martensitic transformations,rather than diffusional ones, such fluxes must be nil. Instiff materials like metals, it has been demonstrated thatthis condition can only arise when the heterophase interfaceis an invariant plane, thereby giving a mechanisticinsight into the phenomenological model of martensiteformation. One can foresee multiscale simulations in thefuture that incorporate these notions and hence enablethe influence on the transformation kinetics of furtherfactors, such as the density of dislocations in the matrixphase, to be assessed.5.3.4. International StandingTo a certain extent, the Interface Science community isinternational; research output is published in the openliterature and conferences are often organized on an internationalbasis. The European contribution to this internationaleffort is comparable with those of Japan and theU.S., although some characteristic differences are evident.All three groups have teams of very high quality researcherswith active specialists in all the key experimental andtheoretical activities. The individual teams are well foundedand relatively stable, and are based in a mixture ofgovernment, educational and commercial institutions.Collaboration between teams is very important, and Europeannetworking is good in this respect. Communicationbetween teams if also very important, and the annualcycle of major international meetings held in the U.S. isthe most active. There is a history of financial support forboth basic and applied research in all three groups,although there has been a trend towards more applied workin recent years in Europe and a decrease in the researchoutput of commercial organizations.References1. A. P. Sutton and R. W. Balluffi, Interfaces in Crystalline Materials.Oxford Sci. Pub.,Oxford, 1995.2. R. C. Pond and J. P. Hirth, Solid State Phys., 1994, 47, 287.3. J. W. Christian, Transformations in Metals and Alloys. Pergamon Press,Oxford, 1965.4. MRS Bulletin, ed. T. Diaz de la Rubia and V. V. Bulatov, March 2001,Materials Research Society, Warrendale, PA, USA.5. G. Gottstein and L.S. Shvindlerman, Grain Boundary Migration inMetals: Thermodynamics, Kinetics, Applications. CRC Press, BocaRaton, 1999MATERIALS PHENOMENA165

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART1665.4. NanomaterialsG. Davies | University of Birmingham, Birmingham, United KingdomO. Saxl | Institute of Nanotechnology, Stirling FK9 4NF, Scotland, United KingdomContributors:M. Welland (Cambridge University, N. Quirke, ImperialCollege, London), I. Shanks (Unilever, A. Franks, NationalPhysical Laboratory, UK), D. Fitzmaurice (Nanomat Ltd,Eire), D. Chetwynd (Warwick University, R. Whatmore,Cranfield University), P. Prewett (Birmingham University).All Board members of the Institute of Nanotechnology.The promise of nanotechnology: “So powerful that it willallow desktop manufacturing… So portable that everyonecan reap its benefits… So radical that it will change oureconomic and political systems… So imminent that mostof us will see its impact in our lifetimes.”Kai Wu, Cornell University.5.4.1. IntroductionThe march towards miniaturization carries on at a relentlesspace. The promise that one can obtain more for less,produce smaller, lighter, cheaper and faster devices withgreater functionality while using less raw materials andconsuming less energy is beginning to be realized. Thispromise derives from the world of nanoscale science. It’s aworld which also promises better electronics, computers,communications, improved medical diagnostics and treatments,better environmental sensors and less pollution.The nano world is defined as a technology in which“dimensions and tolerances in the range 100nm to 0.1 nmplay a critical role”.The field of nanotechnology and nanoscience is, by definition,extremely broad and covers everything from electronics,sensors, healthcare and personal care productsetc. through to micro electronic mechanical machines(MEMS). This nano world is not just a promise of greaterthings to come – though it will undoubtedly be a majorfactor in the wealth creation and quality of life of future offuture EU citizens, but is here with us now. The opportunitiesfor industry across the EU are immense as well asbeing extremely varied and exciting (Fig. 5.2). Some havebeen identified and illustrated in the document publishedby the VDI in 1998 – “Innovationsschub aus dem Nanokosmos”– “Innovations in the Nanoworld” and in the UKForesight document – “Opportunities for industry in theApplication of Nanotechnology”, prepared by the Instituteof Nanotechnology (http://www.nano.org.uk) andpublished by the Office of Science and Technology in April2000. In addition, a follow-up document “Nanotechnology:The huge opportunity that comes from thinking small”will be jointly published by the Institute, the DTI andEureka in June 2001. The objective of the latter publicationis to demonstrate to industry that nanoscience isalready changing the face of materials manufacturing.5.4.2. Future VisionsFig. 5.2. Technology Forecasting – courtesy of G Bachman, BMBF, Germany.We are experiencing the second wave of nanotechnologyand nanoscience, where the area has moved on from thefanciful visions of Drexler to the more pragmatic solutionsfor today’s industry(see references). However, the potentialof the topic is not diminished, its potential is enormousand is now built on the foundations of a strong materialsscience base. A large number of the future directions fornanomaterials is outlined in the next section, however it isworth identifying areas that are more futuristic and willcertainly warrant future seed-corn funding.

The science of the nanoscale world is one that is truly interdisciplinaryrequiring a mix of skills from the physical,medical, biological and sociological sciences. The materialsand devices that will appear will come from the developmentof smart tools with “turn-key” operation and anintuitive interface. These problems will best be solved byconsortia including experts in the human-machine interface.It is important to stress that the EU will serve astrategic role by taking the long (>5 year) term view on fundamentalresearch. The shorter term perspective will betterand more properly be taken by the growing businesscommunity in this area.Taking this view the area of nano-materials will offer enormousopportunities to the electronics, medical and biologicalindustries. Massively parallel fabrication, perhapsutilizing directed self-assembly or molecular templates [cf .organic growth] could enable the pharma industry to manufacturenumerous small amounts of a therapeutic candidatein parallel. This would eliminate the time consumingprocess of scale-up in the development cycle. To achievethis requires cross sectoral working involving chemists,biochemists, etc whilst topics such as seeding at surfacesand structures using novel lithographic techniques willneed to be researched. In addition an architecture requiringa fundamental understanding of 3D assembly of complexmolecular structures possibly templated by physicalstructures is essential. Increasingly important will be thestudy of ‘biological’ nanoparticles – that is large naturallyderived biological molecules (proteins, peptides, etc.) asnanoparticles and clusters of nanoparticles and how thisaffects their subsequent properties and interactions withbiological materials.The whole interface between biological systems and functionalsemiconductors remains a relatively unexplored areathat will afford great benefits. The ability of electronic/optical devices to sense minute samples of biological/medical materials in situ and to relay this information to acentral location opens up possibilities for the remote monitoringof patients. This would remove costs from the healthsystems of countries whilst at the same time ensuring thepatient can exist in the less stressful environment of theirown home. The extrapolation to single living cell diagnosticswill be important for future preventative medicine.The extension of Moore’s law is expected to continue forthe next 10 years with devices in their present form. However,looking to the future then single molecule and singleelectron transistors will appear. Again there will be a needfor the design of complex novel architectures to accommodatethese new devices. The materials will be novel aswill gate designs and the interconnects.The need for bigger and faster computers is a given in thefuture world. That they will not look or perform in the sameway as today’s machines is taken for granted. This newworld will be the world of the quantum computer. Itsdesigns are still being formulated, however, what is knownis that it will depend on new materials and compositionsto work. If the binary component, Qubit, depends onatomic spin then materials in which this spin can be“frozen” together with materials to read-out the subsequentbits are essential.A major failing of nanoscience is the lack of understandingof the physics of interaction of objects (surfaces, particles,individual molecules) at the nanoscale. Questions need tobe answered regarding how nanoparticles can be stabilized,and in what media, how nanoparticles interact andinfluence each other, what proportions in a hybrid systemmake a critical difference. How can these characteristicsbe predicted?The need for more and better modelling is becoming imperative.The more of the basic science that can beachieved via machine “experiments”, the faster thethroughput of new molecular combinations for the productionof new materials and nano-structures.The area of Extreme Nanotechnology requires vastamounts imagination and intuition if nanoscience researchis to come to fruition. Its potential is vast and it is properthat the underpinning nanoscience be properly supported.However this should be part of a balanced approachto funding whereby the top down nanoscience and nanotechnologyis not overshadowed since the benefits fromthis area will be considerable in the medium time frame.5.4.3. Research AreasNanofabrication – encompasses the making of things withdimensions less than 100nm and involves lithographictechniques beyond what is possible by optical means.This is building from the top down.There are several materials issues to consider for lithographymoving into the (sub-100nm line-width). In the rangearound 100nm, stepper technology can be used withphase-shift masks, although the masks are complex andexpensive to design and make. In the sub-100nm rangethere is an assumption that, for the foreseeable future, thebasic mechanism for image generation will be eithere-beam or X-ray lithography. E-beam is inherently highresolution and (relative to X-ray) lower in capital cost andMATERIALS PHENOMENA167

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART168materials, but slow as it is a serial technique. X-raylithography is very expensive in capital outlay (synchrotronsources) and mask materials (X-ray masks require heavymetal absorbers on a thin silicon or nitride membrane).New soft lithographic pattern transfer techniques arebeing researched. These include “contact printing” usinge.g. elastomer stamps. SPM techniques can be used fordirect writing of patterns, but are currently very slow. Thedevelopment of an SPM “toothbrush” with millions of tipswould greatly improve the speed of such a technique byenabling parallel-writing.There are two classes of resists, chemically amplified andnon chemically amplified, that can be used for nanolithographybelow 50nm. For the chemically amplified resists,the materials issue is how to control the acid diffusion inthe resist which determines the extent of polymer chainscission or cross-linking. Using chemically amplified resistsis recommended because they have very high sensitivitywhich can considerably reduce the exposure time. Theirresolution is limited by acid diffusion and the best resultachieved has been 30nm lines. The non chemically amplifiedresists are inherently low sensitivity but of high resolutioncapability, and 5-7nm resolution has been achievedwith PMMA. At such resolutions, intermolecular forcesbecome the determining factor. The resist molecular size isaround 2nm but so far no one has been able to get to theresolution where molecule size becomes the limiting factor.That is because the lithography tools, such as e-beam,have scattering effects which create a latent image in resistslarger than the probe size. Clearly, research is neededinto higher sensitivity resist materials that can have reducedscattering and do not need chemical amplification.• Mask materials for nanolithographyNew materials are required that can be used to createrobust, lower cost X-ray lithography masks.• Contact printingIf a “master” pattern can be created by using e.g. e-beamtechniques, then there may be techniques by which thispattern can be transferred to an other substrate. This hasbeen demonstrated using elastomers, but higher resolutionmaterials for this technique would be interesting.Alternatively, work on (non-elastomer or hybrid) couldprovide a technique for rapid and low cost multiple transferof e-beam created images to device surfaces.• Self-organizing materialsThe use of self-organizing (e.g. biological or biological-like)materials could offer a novel method for pattern generation.At the moment such materials do not exhibit the longtermstability or spatial regularity and accuracy necessaryfor use in industrial processes (e.g. for chip manufacturewhere layer-to-layer registration is essential). It may bepossible to externally-impose order over long spatial distancesusing more conventional lithographic methods andrely on local order using a self-organising system. Combinationof top-down and bottom-up areas of nanotechnologyand the materials issues associated with this may haveinteresting implications.Many techniques exist for building up materials (both organicand inorganic) at the molecular level. Most of theseprovide nanostructures in 1 or 2 dimensions. There will be aneed to be able to pattern on the nanoscale in 3-D. Technologiesneed to be developed over a wide range of materials.Nanometrology – the precise measurement of structuresfabricated with dimensions less than 100 nm. It also includesthe development of such measurement techniques.This not essentially a materials issue, however the abilityto handle materials what ever their form and state is important,both for nanoscience research and for nanotechnology.For nanoprobe analysis, e.g. using STM/AFM etcthen these techniques require the manufacture of tips thatare chemically inert, physically stable and can be fashionedreproducibly into atomically sharp points.The metrology challenges of pushing towards shorter wavelengthson ‘conventional’ steppers probably remain in thedomain serviced by laser interferometers (although thepicosecond ultrasound laser sonar technologies may offeran alternative measurement method for opaque nanoscalemultilayers). There is some argument for using the latticeof a wafer as the displacement reference (together with acoarser scale etched onto its surface). However, the difficultyof getting strong signals and contrast fringes byusing X-ray interferometry for the read-out seems too high.STM, or similar readout, of the reference lattice might justbe possible. The technological limits also need to beestablished. Good mechanical and servo design are thecritical issues for next generation steppers. Metrology ofnano-artefacts – proving that the nanolithography doeswhat it should – is a bigger technical issue for which thereare no obviously dominant technologies. SPMs needbetter (and traceable) internal metrology. This includesforce as well as the main displacement axes. There are stillmajor problems with tip characterization – geometry,chemistry, etc. – for use under industrial conditions. SPMsonly deliver atomic resolution on very smooth surfaces.How can the quality of a groove that is supposed to be10 nm wide and 10 nm deep be assessed? It could be thatonly electron microscopes can do this, however it is expen-

sive to get good quantitative information. There is worthwhileresearch in looking for materials that can give anindirect measure – for example, their response to thestructures of interest is to grow (upwards) in characteristicways that can then be measured with, say, an SPM.Functional nanotechnology – describes applications inwhich nanostructures are used to produce improvedoptical, electronic and magnetic properties.Moore’s law will continue to dominate the electronics industryfor the next ten years. The lithographically defineddimensions of semiconductor devices are already close tothe 100nm range with minimum thicknesses down to the10nm range. However, there will be an increasing demandfor materials combinations of semiconductor, insulatorand metal layers where the dimensions of the layers couldbe at the atomic layer limit – well into the nanoscale. Thesematerials will exhibit novel functional properties not foundin nature and will be dependent on quantum effectsarising from the thickness dimensions.The move to 1D and 0D structures will need to beresearched. 1D structures are quantum wires whilst 0Dstructures are quantum dots. Quantum dots are in themselvesnanoparticles with general properties described inthe sections below, however, in their semiconductor formthey can be produced to give novel optical properties whichcould find uses across the whole of the IT and telecommunicationsindustry. Manufactured in other materialsthen novel phosphors may be produced. They could havemajor applications in crime prevention.A barrier to the introduction of nanoelectronics, is thatthere is no established mass production techniques forcreating devices. Research needs to be done to establishhow a nano three terminal device will be fabricated on alarge scale over large areas, in what will be novel materials.The architecture for such processes needs to be established.What has been described for novel functional materialsalso needs to be applied to new insulators and metallicstructures without which no device can function. Newmaterials need to be researched which will facilitate heatand electrical insulation as well as heat and electricalconduction on such small scales.One can envisage research at the nanoscale enabling –new high speed MQW devices needed for very high datarates, ultrafast optical switches for all-optical networks,amplifiers that can operate at wavelengths inaccessible toexisting erbium doped fibre amplifiers and microscopicoptical benches for precise positioning of new opticaldevices.Ferroelectric materials offer a wide range of functionalproperties (dielectric switchability, piezoelectricity, pyroelectricity,high permittivities, strong electro-optic effectsetc) in a wide range of forms (polymers, oxides, organic andbiological). It has been demonstrated that the effects persistat the nanoscale. It has been shown that ferroelectricthin films can be fabricated which show ferroelectric propertiesin layers as thin as 2 molecular layers, and domainscan be switched and read with a demonstrated resolutionof 40nm. Smaller resolutions are probably possible. Thereare therefore exciting possibilities presented by the usenanomaterials in a wide range of functions, includingmemories, high frequency filtering, optical and photonicdevices etc. Research is required into both the fundamentalproperties of these materials at the nanoscale and theirmanipulation and exploitation in this range.Ferromagnetic materials are of interest for high densityarchival storage systems. There is some research onsystems and their fabrication and this could be a fruitfularea for expansion beyond the nanoscience stage.Organic thin films are as yet largely unexplored by comparisonto semiconductor layers. However, constructed ina similar manner they could be fabricated to respond tospecific and different organic and inorganic materials.These could find applications in a multitude of sensorsand new types of optoelectronic displays.Chemistry is the basis to understanding and providingunique material properties. An example is the manipulationof conductive and semiconductive compounds, e.g.organic polymers, to increase the carrier mobility (> 1 cm 2V-1 s-1). This may be achieved by control of the packing, ofsay the polymer chains, at the nm scale. Molecularwires/rectifiers are a longer term goal, but there are moreimmediate applications to organic LED technology andgenerally to ‘organic electronics’ (smart cards and radiofrequency Identity Tags – applications where processingspeed are not vital). There may also be implications for themicroelectronics industry (spin devices, resonant tunnellingstructures, single electron transistors etc.). There arealso many non-electronic applications, e.g. fashion industry(‘smart’ clothes ), decorative finishes that respond toenvironmental changes. Or, one could combine this areawith electronics, e.g. wall displays, photovoltaic wall coverings.Novel piezoelectric materials need to be createdso as to be “smart”, i.e. materials that can both sense andrespond to the surrounding environment.MATERIALS PHENOMENA169

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART170The development of new fields of science and technology,such as quantum computing, will requires the developmentof entirely novel materials systems. The importanceof this field cannot be emphasized enough.Nanomechanical devices and machines – an extensionof the present day micromachines and microactuators intothe nano world.At present the whole world of MEMS – micro electromechanicalsystems – uses conventional materials be itsilicon, glass or metals. As the dimensions contractprogressively moving into the nano world, then differentmaterial properties, are needed, especially in terms of theirrelation to surface properties, whether for lower friction orreduced surface tension. The incorporation of basic selfassembly techniques is already occurring, and researchneeds to focus on building from the bottom up to producethe next generation of nano devices. The possibility ofmany microreactors or micromachines in a massively paralleloperation describing the nano factory of the futurebecomes an engaging possibility. Nanosensors for force,acceleration, pressure and other measurements will beboth demanded and enabled by such developments.Chemical and biochemical nanosensors will also berequired and might be made using carbon nanotubes (seelater) containing enzymes or electroactive molecules.Molecular motors, such as those used in muscles or bacterialflagellae, may be of use in pumping or controlling fluidflows on this scale.This requires further nanoscienceresearch, however, as does the reluctance of fluid flows tomix at the nanoscale.If very fast NEMS systems can be made, they could finduse as fast actuators where very small forces are required.Tribological issues must be addressed and the use of drylubricants is of interest because of the surface tensionproblems which limit wet lubrication. Surface modificationby ion implantation has been used in macroscopicapplications and it should be considered as part of thearmoury of tools for the nanoengineer/scientist.Molecular nanotechnology – the technology of molecularsensing and molecular recognition. It reflects theinterface between the biological/medical and inorganicsystems.In order to create new and more effective biomaterials,work at the nanoscale needs to accelerated. This will leadto the customization of material and surface finish requiredfor a particular application. Characterization of materialsat the nanoscale is vital, for example, in prosthetic replacementsfor bone and teeth where special load bearingstrength and biocompatibility characteristics are required.It is the properties at the interface of the surfaces, whichcan dictate the properties of the material as a whole. Interactionsbetween polymers and organics can be fine tuned,and their performance consequently changed, giving riseto new phenomena as a result. For example, a nylon nanocompositewith only 2% organics exhibits:- Increased elasticity and strength- Increased heat resistance- Increased toughnessConsiderable research is required to understand how thechemical composition of materials affects the interfaceproperties, critical to the design of new materials.It has been also been known for a while that the morphologyand topography of a surface dramatically affect thebehaviour of living cells on that surface. Further basicresearch on nano and textured surfaces to understand whatmakes them cell friendly and encourages cell growth.Directing the growth of nerve cells on micromachinedstructures is the first step in bio-computing.The use of DNA, which can conduct electrical signalsas well as act as a structural material requires furtherresearch, as the basis of many applications including thepossibility of making biological robots.Nano particles are being used for drug delivery. Surfacemodification of the particle will allow for more effectivedelivery or target existing drugs. This is a vast materials areafor the pharmaceutical sector. Nanoparticles are also beingdeveloped as delivery mechanisms in gene therapy – ameans of rectifying genetic disorders. Good DNA is insertedinto specific sites in target cells to replace faulty genes.Effective particle and materials design is the key here.Microfluidics are an essential part of the drug discoveryand evaluation procedure. Pico and Femto litres of materialcan be examined in this way. The drive is to reducedimensions even further and to be able to examine theeffects of new drugs on single living cells, or on organellesor viruses, within them. Allied with combinatorial chemistrythe whole area of the lab-on- a-chip becomes a viablealternative. Materials properties are essential in that flowand surface tension become critical if this area of sensorsis to become commercially viable. The extension of thistechnology to incorporate micro/nano fluidics with activedevices such as semiconductor devices is as yet almost

unrealized. This opens up possibilities for in situ monitoringof patients by remote means. Thus removing costsfrom the health system whilst ensuring the patient canexist in the less stressful environment of their own home.All of this could be very valuable, but most of it willrequire substantial nanoscience research before it can berealized.Particles, clusters and catalysis – on the nanoscale promisenew and improved properties capable of producing amultibillion pound industry for the 21st Century that promiseeven greater innovations than did their predecessorColloid Science during the 19th and 20th Centuries.The ability to control the morphology and size of nanoparticlesis of fundamental importance, as well as establishingmeans to stabilize them. Research into modifyingthe surface chemistry of nano particles fabricated frommetals, semiconductors or ceramics to produce multifunctionalgroupings is needed, as the basis of many newproperties and applications (Fig. 5.3).Further research is needed into nanoparticulate catalystsand the phenomena that affect their reactivity. An understandingof the nature of these active sites has provendifficult but essential. However, an understanding of theeffect of the material properties and surface morphologyon the efficiency of the process is even more recondite.The ability to design and mass produce nanoparticles of agiven shape, size, size distribution and composition hasimplications for many aspects of materials science withapplications in drugs, cosmeceuticals, coatings, paints,pigments, composites, and lubricants. Depending on thesurface modification of nanoparticles, improved, optical,structural, thermodynamic, viscosity, mechanical, absorption,reactivity and magnetic properties can also be controlled.Nanostructured materials – where the grain and compositesize is less than 100nm, offer the potential forstronger, more wear and corrosion resistant materials.The grain size of materials affects their characteristics. Thisis related to the large area of grain boundary per unit weightof material. More research into these effects will underpinmuch of the future applications of materials science.MATERIALS PHENOMENA171Fig. 5.3. Applications for nanoparticulate research – courtesy the Institute of Nanomaterials, Saarbrücken.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART172Presently one effect of nanoparticles is seen in the use ofmodified clays in plastic composites to give improvedstrength, heat stability and barrier properties. New compositesneed to be researched with novel propertiesdependent on the incorporation of nano-sized materials,and the effects of shape, distribution, volume etc; and thecomposition of substrate and additive. Composites willhave wide range of applications ranging from structural,environmental, healthcare to catalysis.Further work also needs to be done on nanocrystallinematerials to gain an insight into strength and durabilitycharacteristics over a wide range of compositions with improvedproperties of hardness, wear and erosion resistancefor tips for nanomachines and devices. Some investigationneeds to be undertaken into characterising superplasticityregimes.The novel use of nanocrystals currently seen in photovoltaiccells demands more research into the type of semiconductorused, which needs to have surface for light absorptionand charge separation, and may have major implications forother applications. This offers great promise to enable largescale storage of solar energy as combustible gases.Other developments in this area include composite materialfor flat panel displays which could be screen printedover large areas.“Extreme” nanotechnology – represents atomic and molecularmanipulation and assembly. That is building fromthe bottom up. This field is the most speculative but promiseslarge long term gains.This area is as yet a white board for novel materials. Thechallenge is in economic scale up, at as close to ATP aspossible. This may be achieved through self assembly, theuse of biological techniques, or mass production fromarrays of nano tools.Further research into carbon C 40 , C 60 and C 70 molecules,known as “bucky balls” will lead to a more comprehensiveunderstanding of their properties. The ability to incorporateother molecules into molecular carbon cages couldlead to whole new families of novel compounds. Carbonnanotubes are also relatively little understood though theirpotential uses are considered to be numerous. Theseinclude mechanical devices such as probes for STM/AFMetc, to providing novel electronic optical and other functionalproperties for incorporation into a variety of devices.Carbon nanotubes offer promise as electron field emittersin panel displays, single – molecule transistors, gas andelectrochemical storage, catalysts, sensors, protein supports,and molecular filtration membranes.Further research into self assembly using techniques suchas supra-molecular chemistry and how molecules can bearranged into more complex structures has many implications.Designer structures can be formed that arrangethemselves into functional entities held together by anadvanced “molecular glue”.Biomimetics – copying nature’s techniques as a basisfor creating materials with novel properties, or using/modifyingexisting materials produced by livingcreatures, or using organisms as the basis of novel materialproduction.Nature has created many materials from which sciencecan learn. Research needs to delve further and emulatenature’s processes. Already a novel method of capturingenergy by creating a solar cell which is based on how a leafcell photosynthesizes has been developed. Other lessonscan be drawn from the properties of cell walls which canlead to the creation of new thin films with many properties;the strength of shells derived from their crystallinestructure and the intercalation of organic films, which canlead to the manufacture of stronger and lighter materials.Research into the lessons of the biological world will leadto self assembly techniques, biocompatible high strength,lightweight materials, medical glues and sutures that arenot rejected by the body, the development of porous structuresthat can be filled as required, high strength lightweightstructures for macro load bearing applications;biological based mass production of designer molecules,novel filters for toxic gases and liquids, scaffolds and soon. Emulating the design of unicellular animals such asforaminifera, diatoms, radiolaria and coccoliths will haveimplications for the design of nanomachines.Computer modelling – simulation at the atomic level isneeded to understand the new physics of the nanoworld.Through this, performance and chemical/physical characteristicsof novel materials may be predicted.With the increasing possibilities of nanotechnology thenthe need for more and better modelling becomes imperative.The more that can be done via machine “experiments”enables a faster and more cost-effective throughput ofexamination of new molecular combinations and nanostructures.This will underpin much of the nanoscienceresearch conducted, be it top down or bottom up.

At this time the ensemble of modelling techniques form aset of modelling bridges between technology islands. Forexample electronic (dealing with electrons, eg densityfunctional methods) and molecular (molecular dynamics,Monte Carlo) modelling can make predictions concerningnanoparticles (eg defect electronic properties, wettingproperties), or macromolecules. The next level of complexityis where we may have clusters of nano-objectsand/or the presence of mesoscale interfaces and wheretimescales approach microseconds, these methods maybe supplemented by mesoscale modelling (eg dissipativeparticle dynamics, continuous time random walk) methods.This will be important for nano-bio materials (wherethe key may be molecular but the door on a larger scale),for nanofabrication where we want to manipulate smallobjects with larger ones, or nano-pattern bulk surfaces;indeed for all of the frontier areas between bulk materialsand nanomaterials.Modelling and simulation in the nanomaterials area is interdisciplinaryin that it involves chemists, physicists, biologists,applied mathematics, engineers interested in particular phenomenaand applications. The present state of the art is onewhere existing algorithms are being applied to new nanomaterials,new algorithms are being developed (eg for electronicproperties, mesostructures, non equilibrium systems) andnew combinations of algorithms explored to bridge the gapbetween nanoscale properties and the consequences fordevices ie for nanotechnology. Research support for all threeapproaches is required if the full potential for modelling andsimulation in nanotechnology is to be realized. As always withnumerical computer based methods, one limitation is thespeed and memory limitations of existing hardware. One challengefor the future is to utilize the power of grid technologiesthrough software platforms such as Cactus [1] to reducecompute power barriers.European levels of funding for nanotechnology are lowerthan in the U.S. Modelling and simulation provides anopportunity to be smarter, quicker. Whilst experimentalprogrammes are vital, high levels of funding for modellingwill help to ensure that more value is obtained fromexperimental programmes than would otherwise be thecase. We have an excellent base of modelling expertise inEurope from which to grow this area.In conclusion, modelling and simulation can play a key role inunderstanding and applying nanomaterials. By supportinginterdisciplinary modelling teams Europe has an opportunityto compete more effectively with the world centres in nanomaterials.One strong recommendation is that European supportfor nanomaterials research should normally require a significantmodelling effort to be an integrated part of the work.5.4.4 . Place of Europe in the WorldIn the U.S., as a measure of the interest and commitmentby the U.S. government, the fiscal budget for nanoscalescience has been more than doubled in recent years:- For fiscal year 2001 the U.S. government allocated $422M- For fiscal year 2002 the U.S. government will allocate$485MIndividual States are also investing to ensure that they canshare in the prosperity and employment that this will bring,e.g. California has invested $100M to prime the creationof a $300M California Nanosystems Institute.Similarly, in Japan the importance of nanoscience to theireconomy is exemplified by the spending of $410M in thelast fiscal year and the setting up of 30 university centreswith expertise in nanoscale science and technology.There is clearly a well defined acceptance in the industrializedcountries that research at the nanoscale is vitally importantfor the future prosperity and quality of life of theirpeoples. The various European countries are investing innanoscale scientific research, to a greater or lesser degree,but there is little or no evidence of a co-ordinated approachacross the whole of the EU. This situation urgently needsto be addressed otherwise Europe will lose the race in thistechnologically vital area. The opportunities in the materialsarena in particular are vast. For example, the market inadvanced ceramics alone is expected to reach $11 billionby 2003. Other materials applications include new coatingsfor data storage, better and cheaper dyes and pigments,lighter and stronger materials for cars, planes and spacecraftand durable anti-corrosive, heat-resistant, water- andeven bacteria-repellent coatings (Fig. 5.4).It is accepted that nanostructured materials have substantiallydifferent mechanical, electronic and magnetic propertiesas compared to conventional materials.Fundamental research in understanding the basic scienceis now essential to lay the foundations for exploiting themultitude of opportunities that will be presenting themselvesin the near future. We need to know,- how to modify surface properties of materials,- how to control the interface composition/structure ofmulticomponent materials to yield different properties,- how new multifunctional nanomaterials can be designedfor different devices.The answers lie in pushing our knowledge beyond presentlimits.MATERIALS PHENOMENA173

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART174AFabrication andApplication of ultrathinLayersBGeneration and Useof lateral Structures< 100 nm1Medicine/Pharmacy/Biology• Biocompatible Surfaces• Diffusion Layers• Photosynthis Films• Si/Organic Coupling• Medical Nanomachines• Ultrafiltration• Biomoleculare InformationProcessing• nm-Electrodes/Cappillaries2 Precision Mechanics/Optics/Analysis• X-Ray Optics• Quantum-Wel-Lasers• Functional Layers(Filtering, Reflection,Minimization, …)• Fresnel Optics• Diffraction Gratings• Mechanical Sensors• Lithography Machines3 Chemistry/Materials• Polymeric Films• Gradient Layers• After-Treatment of Layers• Sensor Surfaces (Bio-, Chemosensors) • Adhesive Technologies (on variable Surfaces)• Effective Catalytic Surfaces •Corrosion Inhibition Layers• Particle Filters• Copy Protection• Structuring via Deposition• Tip Arrangements (for Photo Detectors, Field Emitter Displays, Electro Filters, High Voltage Switches, Solar Cells,…CProduction andApplication ofNanomaterials andmolecularArchitecturesDUltraprecise Finishingof Surfaces• Research on effective Substances• Positioning of Phrmaceuticals• Key-Lock-Material Systems• Nano emulsions• Frictionless Bearings, Lubricants,Vaccum Rotary Transmission• Correction of Polishing Faults• Optics with nm-Accuracy(Stepper Optics, Asphericals,Substrates for X-Ray Optics,Infrared-Optics, diffractiveOptics, Laser Mirrors)• Machines for PrecisionEngineering• Nano Particle Production(Colloids, Pignents, Dispersions,Nano Powder, Nanocrystals,Emulsions, Clusterm Fullerenes,…)• Compound-/Gradient Materials• Supramoleculars Units• Corrosion Inhibitors• Zeolithe Reactors• Weak Magnets / Ferrofluids /Magnetic Particles• Molecular Chemionics• Ceramic Process Technology• Hybrid-, Effect-Pigments• Systems of compacted Nanomaterials (Membranes, reinforced Plastic Material, Light Absorber, Aerogels, Light Emit• Tools and Methods for the Fabrication and finishing with nm-Tolerances and nm-Form Accuracy(Turning-, Grinding- and Polishing Machines)EMeasurement andchemical Analysisof Nanostructures• Research on Adhesion Phenomena• DNA-Analysis• Cosmetic Research• Development of Pharmaceuticals• Analysis of Bones, Skin, Hairs, Teeth• Sreening of effective Substances• Local Action of effective Substances• Cheap Bioanalytics• Analysis of biological Cuts• Analysis of Toxicity• Components (Profilometer/ Iterferometer,Microscopes, Spectrometers,Scanning Probe Tools,Postitioning Components)• Nanolabs (Analysis+Structuring)• Development of functional Tips• Analysis of technical Surfaces• Characterization of PolishingProcesses• Form & Finishing-Measurement• Absolutely Calibrating Systems• Corrosion Research• Single Molecule Analysis• Catalyst Research• Particle and Cluster Analysis• Computer SimulationFig. 5.4. Industrial Relevance of Nanotechnology – courtesy of G Bachman, BMBF, Germany.• Broadly applicable Process and Quality Control (for Layers, Particles, Structures, Functions)• Analysis as Presupposition for the Product Development• Analysis as Aid for teh Development of a new Thinking for Applications in the nm-Range

4 Electronics/Information Technology• Write-/Read-Heads (GMR-Effect)• Data Storage layers• Photonic-Components {+GaN)• Vertical CMOS-Elements• Layers for LCD-Orientation• Waver Bonding• Ferroelectric Films• MBE/MOVPE Methods• Data Storage/Terabit-Chip• Quantum-/Molecular-/Opto-/Vakuumnano-Electronics(Single ElectronLogic, Laser and Light Emitting Diodes,Transistores)• Litography Masks• Structured Write-Read-Heads• Granular GMR-Elements5 Automobile/Mechanical Engineering• Nanotribology• Electrochromic Surfaces• Multilayers• Adhesion Avoidance• Injection Systems(with Nanoholes)• Wear and Tear Sensors5.4.5. RecommendationsIt is recommended that the EU 6th Framework invest substantialfunds in the area that is defined as Nanoscienceand Nanotechnology. The investment should be of equivalentproportions to that being invested by our major industrialblocks, the U.S. and Japan. This must be of the orderof $400 - $500M per annum if Europe is not to be disadvantagedin this technological area that all countries agreewill be vitally important to wealth creation in the future.The area of nanotechnology warrants programme in its ownright where the programme contents are checked forbalance and scientific excellence.The whole needs to be supported by the correct infrastructurerequiring work at all levels and involving everyone fromacademic organisations through technology transfer institutesand to industry. Binding this together should be a pan-European network to disseminate the results quickly withsub-nets for different topic areas and regional requirements.MATERIALS PHENOMENA175ter)• Photovoltaic Cells• Batteries/Fuel Ceells/Condensators• Conduction Pastes• Resists• Inductive Components• Quantum Components• NLO-Components• Metal Pigments for Data Storage• Mounting and ConnectionTechnology• Ceramic Automobil Motor Parts• Light-weight Materials• Functional Layers(Antiadhesion-, Climatization-,Anticovering-Layers,…)• Foils and Vanishes with Colour Effects• Gas Storage• Damping Components• Back Lightning• Superhard AlloysThis paper outlines the areas of nanomaterials that need tobe researched to provide the EU with the technologicaladvantage for future success. The areas of “Extreme” Nanotechnologyand biomimetics require vast amounts imagination,intuition and nanoscience research to come tofruition. Its potential is vast and it is proper that the underpinningnanoscience be properly supported. Howeverthis should be part of a balanced approach to funding wherebythe top down nanoscience and nanotechnology isnot overshadowed since the benefits from this area will beconsiderable in the medium time frame.• Wafer Grinding• Wafer Polishing• Frictionless Bearings• nm-Positioning Technology• Ultraprecision Machines with highFlowrateIt is important to stress that the EU should serve a strategicrole by taking the long (>5 year) term view on fundamentalresearch. The shorter term perspective will better and moreproperly be taken by the growing business community inthis area.• Structure Analysis• Elemental Distribution(Doting, Compositional andOrbitalcontrast Measurements)• Metrology• Wafer-Inspection• Magnetic Storage Analysis• Control of Layer Growth• Optimization of Signal/Noise Ratio• Friction Analysis• Roughness• Hardness and Elasticity of Surfaces• Microfabrication in Microscopes withbig Volume• Nanosimulation of MaterialComponentsThe need for more and better modelling is becoming imperative.The more of the basic science that can be achievedvia machine “experiments”, the faster the throughput ofnew molecular combinations for the production of newmaterials and nanostructures.It should not be forgotten that this investment will have amajor impact on education across the whole of the EU andwill provide the skilled workforce that will be necessaryto keep the EU at the forefront of this technology race.Coupled with this should be significant public relationsprogramme to keep the citizens of the EU informed of themajor benefits of nanotechnology and nanoscience to theirlives.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART1761.2.3.4.ReferencesCactus is an open source problem solving environment designed for scientistsand engineers. Its modular structure easily enables parallel computationacross different architectures and collaborative code developmentbetween different groups: seehttp://www.cactuscode.org/Documentation/Introduction.htmlA primary source of information is the Institute of Nanotechnology and itswebsite. http://www.nano.org.uk which has links to companies, laboratoriesand academic institutions involved in nanotechnology in the UK andworld wide. There are also reports and articles on nanotechnology and itsapplication.For information on precision engineering and nanotechnology, contact DrDebbie Corker at EUSPEN – The European Society for Precision Engineeringand Nanotechnology: debbie.corker@cranfield.ac.uk and visit its websiteat http://www.euspen.org/The EU has recently completed an important ‘Technology Roadmap forNanoelectronics’ which can be found on the EU’s CORDIS website athttp://www.cordis.lu/esprit/src/melna-rm.htm5.6.7.8.Within the EU there is an increasing emphasis on nanotechnology withfunding for research and development projects that affect the key objectivesof EU policy: quality of life for the ageing population, sustainabledevelopment, crime prevention and so on. Individuals with responsibilityfor co-ordinating nanotechnology R&D in the EU are Bernardus Tubbing:bernardus.tubbing@cec.eu.int andRamon Compano: ramon.compano@cec.eu.intA useful German nanotechnology website, http://nanonet.de links tocompanies and projects Germany wide: likewise the TEKes website hasinformation on nanotechnology activities in Finland, http://www.tekes.fi/For information on nanotechnology in the US visit the NASA website;http://nasa.gov or http://nano.gov and the website of Loyola University,http://www.loyola.ede which has many nanotechnology articles and acomprehensive database on companies, academia and research.There is also a Swiss nanotechnology initiative, TOP21,http://www.ethrat.ch/topnano21/For information on the US National Nanotechnology initiative seehttp://www.nsf.gov/home/crssprgm/nano/start.htm5.5. Small-Scale Materials and StructuresE. Arzt and P. Gumbsch | Max-Planck-Institut für Metallforschung, 70174 Stuttgart, Germany5.5.1. Introduction“There is plenty of room at the bottom”- the vision of extrememiniaturization, expressed in a celebrated 1959physics lecture by Nobel laureate Richard Feynman [1],has since then remained an important scientific challengeand guideline for the development of new technologies. Alarge fraction of modern materials research has been devotedto this goal, but the major benefits of such a microandnanostructural design still lie ahead of us.To realize such objectives, one of the indispensable areasfor future research and development is the controlledstructuring of materials on all length scales. This appliesnot only to the precise and accurate shaping of materialsto defined external structures but also at the same time tothe control of the internal microstructure of the material.This internal microstructure encompasses the granularityof the material and includes materials defects like inclusions,surfaces, internal interfaces, dislocations andmicrocracks, which in their entirety determine the macroscopicproperties of the material. Artificially structuringmaterials on the nanometre scale or even the atomic scaleis of particular interest since “mesoscale” effects occurthere which open up entirely new possibilities for applicationsin (nano)electronics, measuring and sensing [2].Fig. 5.5. Atomic ring structure displays mesoscopic quantum effects.(Taken from [2]; originally from IBM).Today materials synthesis is usually characterized by theaccidental nature of microstructure formation. Drasticallyimproved materials performance, reliability and reproducibilityis expected if the formation of the microstructurecan be controlled and adjusted on all length scales. Theassembly of complex materials by controlled manipulationon the nanometre scale will make use of advancedlithographic methods but will also include new designprinciples, such as self-organization by stress fields or(bio)chemical reactions.

Further advancements in synthesis as well as the ability totailor-make materials with specific properties criticallydepends on the ability to model materials microstructure,properties and the processes used for synthesis. Advancesin the description of atomic bonding together with theincreased computing power have opened the possibilityfor the simulation of chemical reactors and manufacturingprocesses which lead to a new degree of prediction ofmaterials structure and performance.5.5.2. Design of Small-Scale StructuresThe performance of today’s computer technology was enabledby the down scaling of characteristic feature dimensionsof electronic components from a few microns to afew tenth of a micron. This allowed the realization of processorswith ever increasing operating frequencies as wellas smaller and faster storage components. During the lastdecade design ideas and fabrication methods from theworld of micro electronics have started to inspire other disciplineslike the popular field of MEMS (Micro Electro-Mechanical Systems) which led to the creation of miniaturesensors (e.g. accelerometers) and micro actuators(e.g. valves, mirrors). Incorporation of such miniaturedevices into small scale systems will lead to improved performancesuch as increased power density, improvedsystem reliability through component redundancy and insitu monitoring of critical components.Materials research will be a key element in the realizationof new miniaturized devices. The variety of materials whichcan be processed with micro fabrication techniques isexpanding rapidly and ranges from plastics, to metals, andceramics. New high-performance materials will urgentlybe required for small engines, micro fuel cells, embeddedmicrosensors and actuators. These may be developed followingentirely new engineering design principles, includingthe use of materials in applications where they couldnot be used previously. System redundancy may for exampleallow the use of brittle materials in mechanically loadedsystems. Furthermore, such new fabrication methodsmay also lead to the manufacture of novel materials, e.g.with negative coefficient of thermal expansion or negativePoisson’s ratio. It is immediately clear that materials anddesign issues are intimately connected in the developmentof micro-components and need to be addressed together.This will require the cooperation of materials and mechanicalengineers, even to a greater degree than in today’sdevelopment of large-scale components.5.5.3. Interfaces and Composite MaterialsFor ever smaller structures, surfaces and interfaces gain inimportance as the surface-to-volume ratio increases. Weneed to develop, therefore, greater understanding of therelation between structure, thermodynamics and properties(diffusivity, reactivity, segregation behaviour, equilibrationconditions) of surfaces and interfaces. Surfacesand interfaces obviously dominate adhesive and frictionalproperties of small scale materials. In particular, they alsoaffect the plastic response of a material and the brittle orductile behaviour. Artificially layering compounds withdifferent properties or different internal stresses will allowcircumvention of classical trade-offs and lead to newmaterials with unprecedented combinations of strengthand toughness, conductivity and hardness or magnetic andmechanical strength.A common weakness of small structures is their limitedthermal stability. The reason lies in the fact that kineticmaterials processes are size-dependent on a variety ofscales. Examples are the equilibration of surface and interfaceshapes, the interfacial reactions (including the formationof non-equilibrium phases), and the formation ofmesoscopic interface structures such as ledges. Assessingthermal stability of metastable structures requires detailedunderstanding of the interfaces involved in nucleation processes..The main unknown is the energy of the interfacebetween a second phase nucleus and the matrix. Determiningthis energy is particularly challenging in the case ofnucleation from a liquid, since the interface is difficult toaccess experimentally, and modelling of its structure andthermodynamic properties is complex. However, the smallsize and the low stability of very small structural elementsopens the possibility to use self-assembly and similar methodsfor structuring, which rely on small driving forces.Organic thin films are in many ways different from metallicor ceramic ones. By constraining a polymer to a thinfilm, its conformation can be quite different from that inthe bulk. Organic monolayers, often self-assembled, eitheron a substrate or as a membrane, have unique structure,thermodynamics and mechanical and functional response.They can also be used to coat small particles and thin filmsto induce functionalisation and self-assembly. Researchalong these extremely promising lines is only in its infancy.MATERIALS PHENOMENA177

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART1785.5.4. Interface to Biological MaterialsLessons from biology can fertilize materials research inmany different ways. Three billion years of evolution pacedby stress (“Survival of the fittest”) has produced a numberof remarkably efficient materials and molecular devices(photosynthetic centre, efficient molecular motors, controllablemolecular channels). The use of such moleculesin assembling inorganic matter into functional materialscould potentially revolutionize materials synthesis.For example, spontaneous organization is an almost universalfeature of complex biomolecules that renders themideal for fabrication, provided we can engineer them to ourneeds. By an appropriate choice of functional end-groupsof the self-assembled monolayers intelligent substrate surfacescould be created allowing selective bonding betweenmany different materials. Tiny particles of insulators, semiconductorsand metals can be organized into functionalmaterials, a process that produces materials from the “bottomup” rather than from the “top-down”. No lithographywill be needed to realize specific mesoscopic structuresand it can be foreseen that self-organizing concepts will beused for fabrication in different ways.Nature can also inspire materials research in the creationof optimized interfaces and surfaces. In a rather counterintuitiveway, finely structured shark skin was found toexhibit better hydrodynamic behaviour than perfectlypolished surfaces. Similar surprises happened in thesearch for non-wetting surfaces (“Lotus flower effect”). Inthe field of microtribology, optimally structured surfaceswere found in insects which could guide the developmentof microstructured reversible adhesive contacts.In small-scale materials the internal and external structuresizes overlap with the biological scales which in principleallows more detailed studies of the intimate contactbetween inorganic structures (machines) and living organismsor cells (see Fig. 5.6) reaching as far as exchanginginformation across such contacts [3]. Better control ofthese interfaces will change our possibilities for activatingor passivating surfaces for the contact to living organismsand may open new ways for medical treatment. However,this will require much more intense collaboration betweenbiological and materials research which will very likelyproduce exciting materials innovations in the future.5.5.5 Understanding Materials Across the ScalesFig. 5.6. Neuron on an oxide-covered silicon chip. (From Ref. [3]).An important issue in materials science is how mechanicalproperties such as strength, hardness and toughness,magnetic or electrical properties scale with the characteristicsize of a structure. This issue is especially importantfor materials problems in micro- and nano-technology.Computer modelling has become an indispensable instrumentfor the advancement of the theoretical understandingof materials, particularly for small scale materials andsystems, where the magnetic, electronic or mechanicalproperties directly depend on the internal (microstructure)and external (shape) structure. Particular attentionhas recently been directed towards the question whetherand how the properties of a functional system can be predictedon the basis of its known atomic or molecular composition.This depends critically on the understanding howa particular crystal defect or a particular molecule contributesto the collective materials properties and the functionof the system. The simulation or prediction of such effectsrequires the connection of different modelling schemeson significantly different length and time scales. Manyfundamental aspects of such a connection remain to beexplored, particularly for the connection between discrete(atomistic) and continuous models.

Experimentation and simulation are equally important toadvance the understanding at this transition between differentscales and different phenomena. Particularly in situexperiments geared towards testing modelling predictionswill be of greatest need. This need is generated firstly bythe fact that the small scale structures are usually metastablestructures, far away from equilibrium where transientbehaviour is of outstanding importance. Secondly,the modelling of scale transitions usually involves multiplephenomena which can not be separated and therefore haveto be compared directly to (in situ) observations. The combinationof in-situ experimentation and simulation will beparticularly fruitful in understanding nucleation and interactionof crystal defects which are the basis for the theoreticalmodelling of the mechanical properties, plasticity,fracture and fatigue of small scale materials. Similarly, recentadvances in micro-focus X-ray diffraction or in situmicroscopy techniques enable materials synthesis or depositionprocesses to be studied; this will allow validation ofcomputer simulations of the microstructure formation, ofnucleation and growth phenomena. Considerable researcheffort is, however, required to reach these ambitious goals.5.5.6. International Situation and Current Needs in EuropeThe international situation in the research on small-scalematerials and particularly on nanotechnology has changedsignificantly over the past few years. It was characterizedby almost equal strength and similar amounts of governmentexpenditures in the U.S., Japan and Europe [4]. Europewas among the world leaders mainly in analyticalmethods, lateral nanostructuring and ultraprecision engineering.Funding has been increasing moderately. Themain funding sources are the 5 th Framework Programmeof the EU and national nanotechnology programmes likethe German BMBF-initiative “Nanotechnologie”. Theparticular strength of Japanese research is in quantumfunctional devices and (nano)biotechnology. Nanotechnologyresearch in Japan also benefits from a very strongindustrial research effort with many close collaborationsbetween industrial research centres (Hitachi, NEC,Toshiba,..) and academic or other government fundedresearch. In the U.S. the entire small-scale materials sectorgot a huge boost through the National NanotechnologyInitiative which effectively tripled government expenditureon nanotechnology within the last 3 years (to about0.5 billion Euro in 2001 [2]). This enormous drive towardsnanotechnology gave U.S. research a very significant competitiveadvantage not only in funding but also in publicawareness in identifying nanotechnology as a key intellectualand economical subject of the future.Current weaknesses in Europe are: a lack of a unifyingview on small-scale materials and systems including theirmanufacturing, analysis and their performance throughthe entire life cycle, a lack of intellectual drive towards materialsscience in general and a lack of cross-disciplinarycollaboration in the research for new small-scale systems.Furthermore there is also a lack of entrepreneurship inconnection with and around the research programmes particularlyin comparison with the situation in the U.S. Allthese weaknesses would vastly benefit from a large-scaleconcerted action towards materials research for which theresearch on small-scale materials is a spearhead.5.5.7. ConclusionsThe field of small-scale materials and structures is particularlypromising for creating scientific and technologicalbreakthroughs and innovations. Studies of size-effects onthe behaviour of materials and the functionality of systemsare at present only in their infancy and will require substantialresearch efforts. Of paramount importance will bean integration of manufacturing control, the simulationand the specific adjustment of the properties and theprediction of their development during the service life ofthe systems. Further progress in this area will criticallydepend on close collaborations of materials scientists withphysicists and mechanical engineers, on the one hand, andbioscientists, on the other.References1. R. Feynman´s talk at the 1959 annual meeting of the American PhysicalSociety. (http://www.zyvex.com/nanotech/feynman.html )2. C. Macilwain, Nature 405 (2000) 730.3. S. Vassanelli, P. Fromherz, J. Neurosci. 19 (1999) 6767.4. R. W. Siegel, E. Hu, and M. C. Roco, eds. NSTC Report “Nanostructurescience and technology” Baltimore: International Technology ResearchInstitute, World Technology (WTEC) Division, 1999.(http://itri.loyola.edu/nano/IWGN.Worldwide.Study) Also published byKluwer Academic Publishers (1999).MATERIALS PHENOMENA179

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART1805.6. Colloid Physics and ChemistryM. Antonietti & H. Möhwald | Max-Planck-Institut für Kolloid- und Grenzflächenforschung, 14476 Golm, Germany5.6.1. IntroductionColloid chemistry and physics is the science of making,characterizing, and examining the properties of objects ormatter structured on the length scale of some nanometres.The relation to modern notations such as “nanotechnology”,self-organization into ordered “nanostructures”, “nanocomposites”,or “nanoparticles” is obvious, and colloidscience is the scientific base of a whole range of applicationsin modern technologies.[1], which put 422 million $ into nano-sensitive infrastructure,and a significant part of it in the above mentionedfields ; this corresponds to a total budget increaseof 56 %. Corresponding European programmes are stillmissing such that there is serious chance of loosing therace for the best heads and the best innovations in thisvery promising field between Asia, Europe, and America.This is why joint efforts in previous and current strongholdsin this area are to be kept or to be established, andmust receive better support.An important differentiation to be made is that not all partsof nanotechnology are based on colloids, since colloidscience historically focuses on solution or wet chemicalprecursors, but does not consider gas phase procedures orsolid state approaches towards nanostructured elements.In colloid science, there is also a certain dominance of softmaterials (polymers, surfactants, supramolecular units,bio-matter), but components made of metal, semiconductors,or ceramics are also quite frequently used. It is justthat the approaches in classic semiconductor science orsolid state physics are clearly different from the approachesused in colloid science.5.6.2. Status of the Field and Deficiencies in EuropeThe field has experienced large sophistication (and an unparalleledscientific renaissance) within the last 10 years,and major scientific trends arising from colloid and interfacescience were for instance nanoparticle research, selfassembledmonolayers, ultrathin organic layers, as well asthe development of casting and template techniques. Thebreakthroughs also arose from development of modernanalytical techniques like scanning probe microscopies,neutron-, X-ray-, and light scattering that were able todescribe the objects of interest, bridging the dimensionalgap between the macroscopic, solid state world andthe former chemistry of molecules. Those recently grownfields will continue to drive the development of newmaterials, but the colloid science in itself and the needs ofother disciplines will create a number of new light signalswhere colloid science might go to.One of the most visible political decisions of the last yearswas the “National Nanotechnology Initiative” of the NSF5.6.3. Future VisionsIn the following, we will list from our personal viewpointsome selected breakthrough fields where we expect majordevelopments with either strong scientific impact or benefitsfor the society.(a) Nanocomposites for engineering purposesThe hybridization of organic and inorganic matter on thenanometre scale, e.g. polymers and inorganic or metallicnanoparticles, will add a new class of materials in betweenpolymers and ceramics [2,3] It is expected that those materialsshow the easiness of processability of polymers, butinherit some of the properties, e.g. scratch resistance ormagnetism, of the inorganic side, too. Scratch free plasticcar windows (for light-weight construction), light-weighteye glasses, highly resistant coatings and paints formachines and furniture, carbon nanotube reinforced thermoplasts(improves mechanical stability, conductivity, andenables recycling), or the fuel saving “green tire” are justsome examples for nanocomposites to be made with theclear potential to impact technology and society.(b) The interface between the bio-world and materialsThe coexistence of biological objects, such as cells, andtechnical devices, e.g. in biosensors, for artificial senses, inprostheses, for artificial organs and in tissue engineeringwill continue to demand a set of instruments for an “interfacing”between the two worlds. The notation “interfacing”contains elements of the physicochemical interface, that isthe adaptation of chemical functionality, conductivity orelasticity, but also elements of informatics, that is the possibilityand encoding of information transfer throughoutthe boundary between biological and artificial world [4].

Molecular or colloidal “chimeras” such as polymers withbiological parts and synthetic blocks are starting to bedeveloped in tissue engineering [5] and are regarded asfirst steps towards “amphiphiles” (= both loving) for thisspecial problem.(c) Biomimetic material scienceThe superb performance of biological material such asbone, seashells, wood, tendon, hair, or spiders´ silk is dueto a hierarchical superstructure of the materials wherestructure control is exerted at every level of hierarchy [6,7]In addition, it must be pointed out that those materials arecreated around room temperature, represent in many casesoptimal cases of lightweight design, are made of simplecomponents such as calciumcarbonate or polypeptides,and are recyclable and sustainable.Procedures have to be developed which allow material scientistsa similar control over materials structure on alllength scales, presumable by combination of traditionalprocedures with new nanometre- and micrometre specifictechniques, such as template procedures, controlled crystallization/growthor directed nucleation of foams [8].(d) Functional thin organic/polymer layersThe further development of thin organic layers onto othermaterials is currently mainly performed for either protectionagainst corrosion or lubrication. The physical/chemicaldesign of more sophisticated functional interfaces willcreate another dimension of possibilities for materialscience. Examples for that are coatings with ultralow-surfacetension (dirt repellent, tribology), surfaces with theability to reconstitute misfolded proteins, or surfaceswhich assist the formation of biofilms (materials coated bywanted bacteria or algae) [9].(e) Catalysts with a rational nanostructureThe increase of the efficiency of large scale chemical andengineering processes, e.g. oil refinement, the redirectionof product streams or fuel cell technology relies mainly onthe development of new catalysts and catalytic procedures.The methanol reforming process (the generation of hydrogenfrom methanol) for fuel cells or a potential efficientrefining of the 20 wt% heavy crude oil fraction are just twoexamples where the advantages for a balanced technologicaldevelopment are very obvious. Although there are conceptsfor such catalysts, their realization relies on a betterunderstanding of the catalytic process as well as the abilityfor a rational design of those structures with characteristicstructural details that are necessarily on the nanoscale andbeyond the tools of classical chemistry.(f) Colloidal diagnostics and drug carriersIn pharmacy, there is an ongoing trend to go from “molecular”drugs to the development of vectors or complete systemswhere the drug or molecule of action is equipped with atransport and protection system and a “homing” device tomake the drug more efficient and to allow applications usuallynot possible for the drug itself (e.g. inhalation or transdermalapplication of insulin instead of injection) [10,11].It is common sense that those active systems are carefullydesigned and composed colloidal entities, where each ofthe components fulfils a special task. Similar argumentshold true for simple, multipurpose diagnostic kids (ordetection kids) for the rapid ex-vivo analysis of diseases,infections, and intoxication of food and water.(g) Colloids with gradients and broken symmetry: directionalforces and differentiated 3d-self assemblyPrevious work on self assembly has shown that thecomplexity of the resulting superstructures is restricted torather simple shapes, which is due to the high symmetryof the starting objects and the connected interaction fields.It is therefore a current task to create building blocks withbroken symmetry such as “Janus spheres” or “Janus coins”are objects with non-centrosymmetric fields which canline up in more interesting (and useful) superstructures,as they are for instance found in living nature. This wouldallow self-assembly to go “around-the-corner”. This topicis closely related to “biomimetic materials” and the questionof structural hierarchies in artificial materials.(h) Complex colloidal entities with function: “nanofactories”and “artificial cells”Recent developments on encapsulation technologiesallow creation of closed hollow objects from polymers orpolyelectrolytes in the micron size range, where functionalitiessuch as ion channels, photoactive sites, proton separation,or chemical gradients can be easily implemented[12,13]. These entities are called “cells” (used in thegeneral semantic notation). Such “artificial cells” or “nanofactories”have the chance to become the most complexartificial objects on the molecular scale which can bereleased with a function, e.g. harvest solar energy, activelycollect heavy metal ions, or release chemicals at outerprogrammed stimuli.(i) New principles for chemistry: compartimentalizationand single molecule chemistryBeside direct applications, colloid science of the next yearsalso has to consider new “instruments” to be brought intomaterial synthesis. One graphic example for those is theconcept of compartimentalization or single moleculechemistry [16]. Compartimentalization is the (biomimet-MATERIALS PHENOMENA181

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART182ic) principle to isolate molecules from each other and toperform complex chemical reactions or folding/crystallizationprocedures. Such a reaction is expected to occur inthe compartimentalized state in a purely intramolecularfashion and obey a higher degree of control. This is importantfor molecules with more than one reaction site or manypossible reaction pathways. Since the processes are doneon single molecules, but in a highly parallel fashion (manycompartments), the mass flux is still of significant size.Obviously, this principle is already used throughoutbiosynthesis, but not applied for artificial systems.5.6.4. Conclusion and RecommendationsIt is not only our, but also the opinion of many technologyagencies that colloid and interface science is one of thereal opportunities to combine a sustainable and environmentallyfriendly development with the forthcoming technologicalneeds of our society [15]. Even more important,some long term goals (like the preservation of the climate,fuel cell technology, energy neutral living areas, low energyconsumption mobility) cannot be reached with thestandard technology, and colloid and interface scienceplays a key role in all solution strategies.Beside of the scientific possibilities and the long termneeds of society, this type of technology has already grownto a major market, and a conservative estimate of the marketvolume for 2001 has lead to a sum of 100 billion DM[16].The European science system is just a the beginning of anadequate reaction, mainly still on the base of small testprogrammes or feasibility analyses. We recommend a fastand substantial reaction, potentially focussed to thespecific demands of society (e.g. by the establishment ofvirtual, interdisciplinary European Institutes coveringtopics such as “Artificial Cellular Nanofactories”, “Catalysis2010”, “Biomimetic Materials”, or “Energy neutralvillages”), where colloid science will certainly contribute.In addition, the organization principles and the reactiontimes of the science support system have to be significantlyde-bureaucratized and shortened.References1. See, for instance: http://itri.loyola.edu/nano/IWGN/#reports2. P. Gomez-Romero, Adv.Mater. 13 (2001) 163.3. L.L. Beecroft, C.K. Ober, Chem.Mater. 9 (1997) 1302.4. P. Fromherz, R., Europ.J. Neurosci. 10 (1998) 1956.5. J.A. Hubbell, Biotechnology 13 (1995) 565.6. S. Weiner, H.D. Wagner, Ann.Rev.Mater.Sci. 28 (1998) 271.7. D.L. Kaplan, Curr.Op.Solid State Mat. 3 (1998) 232.8. S. Mann, Angew.Chem.Int.Ed. 39 (2000) 3393.9. G. O´Toole, H.B. Kaplan, R. Kolter, Ann.Rev.Microbiol. 54 (2000) 49.10. M.C. Jones, J.C. Leroux, Europ.J.Pharm.Biopharm. 48 (1999) 101.11. Y. Nishioka, H. Yoshino, Adv.Drug Deliv. Syst. 47 (2001) 55.12. F. Caruso, R. Caruso, H. Möhwald, Science 282 (1998) 5391.13. F. Caruso, H. Möhwald, J.Am.Chem.Soc. 121 (1999) 6039.14. M. Antonietti, K. Landfester, ChemPhysChem. 2 (2001) 207.15. N. Malanowski: “Innovations- und Technikanalyse Nanotechnologie”,VDI Technology Centre, 2001.16. G. Bachmann, Magazin des Wissenschaftszentrum Nordrhein-Westfalen1/99, 1999.Considering this potential importance, it is obvious thatthe chances for society and the current public funding ofthe topic have no relation. Even the 2.5 % of net cash flowwhich are typical for a G7 country to preserve activeresearch and development in a field are well above anypublic science programme in this field. It is worth repeatingthat both the American and the Japanese sciencesystems already have reacted and started to support thisfield as one of the future key breakthrough fields ofscience policy, both financially and by adequate organizationalsupport.

5.7. Mechanical Properties of Metals and CompositesP. Van Houtte | Catholic University Louvain, Louvain, Belgium5.7.1. IntroductionTopics such as elastic properties of materials, fracturetoughness, fatigue crack propagation, plastic yielding atroom temperature, at elevated temperatures, creep,viscous flow etc. all belong to the concept of “MechanicalProperties”.Furthermore, several metal families are involved, of whichthe main ones are those based on steel, on aluminium, oncopper, on titanium and on magnesium. The number ofresearchers working in all these fields, and the number ofindustries involved, is vast. In this text, focus will be mainlyon metals and on plastic properties at room temperature,including strength and ductility. Even then the varietyof activities, needs and potentialities is great . The presentdiscussion is written with an eye to the future, and willtherefore take the future needs of society as its startingpoint, rather than the present state of the art.5.7.2. Future Needs of Society Regarding Materials forStructural Applications(a) Weight and energy savingBy “structural applications” we understand all applicationsfor which the main function of the material is tocarry a load. In the transport sector (cars, trucks, trains,aircraft), weight savings will become increasingly important,because they are intricately connected to energysavings by reduction of fuel consumption. But there areother sectors as well for which weight savings are important.For examples, by using lighter but stronger materials,it may be possible to make bridges wider without havingto replace the foundations. Not surprisingly, the moststringent demands for weight reductions come fromexpensive products, such as sporting goods for top-levelsports, and of course aerospace.In the decade to come, car body parts from mild steel willpartly be replaced by aluminium alloys, which on theirturn may be replaced later by special high-strengthmagnesium alloys. Reinforcement parts from mild steelare already being replaced by parts from high-strengthsteels, allowing considerable weight savings.The second decade to come will see further weight reductionsby the replacement of some steel parts by carbonfibrereinforced plastic (composite material) or by aluminium-basedmetal matrix composites. Parts from highstrengthsteel may be replaced by high-strength titaniumalloys. Finally many parts from carbon steel will be replacedby stainless steel, which not only lasts longer but also hasa higher strength.In the hulls of recent military aircraft, the share of aluminiumis reduced to as less as 16% and steel to 6%. Theyhave been replaced by advanced Ti-alloys and by polymerbasedcomposite materials. In the civilian aircraft industry,evolution is much less drastic although the evolutionis the same.(b) Micro- and “nano”-technologyThe importance of structures and devices with sizes inthe micrometre-range such as interconnects, microvalves,microswitches, often also deposited on Si substrates, willbecome more important in the future. (This field is oftenreckoned to belong the “nanotechnology” field, althoughits scale obviously is that of micrometres). State of theart is that it is now possible to make such structures ordevices. Optimization of properties has just begun. Morefocus will have to be given in future to the mechanicalbehaviour of these structures or devices. In interconnectsfor example (material: copper or aluminium), the lifetimeand functionality are greatly affected by the residualstresses present. The latter depend on the processing ofthe component, but also on the material properties of theinterconnect, such as elastic constants, and especially thelattice misorientations at grain boundaries. The study ofthis requires advanced electron-microscopical techniqueswhich allow for the simultaneous acquisition of topologicaland crystal texture data, combined with advancedmaterial models such as crystal-level elasto-plastic finiteelement codes. In micromachines (material: often silicon),the grain boundaries are equally important, as theyare potential sources of stress concentration possiblyleading to premature failure of the device.MATERIALS PHENOMENA183

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART184Elongation A 80 (%)6050403020105.7.3. State of the Art and Research Needs(a) SteelsFig. 5.7 shows the combinations of strength/ductilitywhich are available today for steel sheet for car bodies. Thetwo material families at the right (TRIP, high-strengthDual Phase) are still under development. Such steels arevery complex; they contain several phases; the ductility isenhanced by special effects which strongly increase workhardening, such as transformation-induced plasticity.Fundamental research is needed in order to obtain evenbetter materials, for which the bands are shifted either tothe top or to the right. These materials will probablybe multiphase materials as well, or materials with ananostructure, or a combination of both. For example, itis conceivable to develop pearlitic steels with interlamellardistances in the lower nanometre range, which willprobably have superior properties due to the effect of thelamellar structure on both strength and work hardening.Other types of steels which would also exploit the “lamellareffect” are also conceivable. A discussion on the scientificissues related to multiphase alloys is given below.BH0200 300IF HSSP-AlloyedMA400 500 600 700 800 1000 1100 1200Tensile Strength (MPa)Fig. 5.7. Combinations of strength and ductility (elongation) for varioussteel families.(b) Aluminium alloysThe art of using several alloying elements in order to obtainmuch higher strength in aluminium alloys is well developed.One of the most interesting ways to achieve thisis by precipitation hardening. This “art” is now evolving tobecome a “science” by doing extensive studies on theseprecipitates, their crystal structure, the degree of their coherencewith the matrix, their stability. This research willlead in the decade to come to further substantial improvementsof these alloys. One of the questions to be addressedis the study of the stability of age-hardened alloys (an applicationof precipitation hardening) at temperatures in therange of 150°C - 200 °C. High-strength aluminium alloysDPTRIPwhich would be stable in that range would allow for importantweight and energy savings in aerospace applications.Many advanced aluminium alloys are also multiphasealloys. See the discussion on multiphase alloys below.For the rest, more work has to be done on developing reliableconstitutive models to be used in design applications.For some alloy systems, wide-range models exist for workhardening as a function of strain rate and temperature [1],but not for all alloy systems. Moreover, the existing model,how complex it may appear [1], should still be extended toinclude anisotropy and strain path effects.(c) Titanium alloysAerospace industry has developed some truly highstrengthTi-based alloys with very interesting microstructures(some of them lamellar). Some of these developmentsare unfortunately not in the public domain (militarysecrets). Companies which build both military and civilianaircraft can of course apply these alloys also in civilianapplication, which cannot be done by companies whichonly build civilian aircraft. From a more scientific point ofview, many issues remain unresolved, again because notenough is know of the behaviour of multiphase materialsat the micro-to nanometre scale. (See the discussion onmultiphase materials).(d) Copper alloysThe knowledge acquired for other metals (see above) wouldbe used to develop copper alloys which combine a highelectrical or thermal conductivity with a high strength, whichmight have very important technological applications.(e) CompositesComposite materials, either based on a polymer-matrix oron a metal matrix, and reinforced by fibres have a high potentialto develop materials with an extremely favourableratio between strength and weight. The state of the art isthere that these materials can be produced, but that processingstill needs a lot of work to improve. The true understandingof the mechanical properties is now emerging,but still has to be done in many cases. Again they will verymuch depend on the interaction between phases, developmentof stresses, and of course on the understandingof the behaviour of the phases themselves. In view of thehigh potential of these materials, a strong effort for furtherfundamental research to raise it to the same scientificlevel as the research on metals, is imperative.

5.7.4. Scientific Trends(a) Multiphase and nano-structured materialsBefore the material scientists at steel companies, aluminiumcompanies etc. can really design new materials whichderive a high strength from either a multiphase structureor a nanostructure, the institutions for fundamental materialsresearch must provide answers to a certain number ofquestions. A few examples:• By which dislocation mechanisms is work hardeningachieved in the individual phases of multiphase materials?• What are the relations between morphology (e.g. lamellaorientations) and crystallography at the time that themicrostructure is first formed?(This list is not exhaustive). To be able to answer thesequestions, advanced experimental techniques have to bedeveloped, difficult measurements have to be carried out,and the best “tools” of fundamental material physics needto be used. Some questions will require the use of moleculardynamics-type approaches, or, on a slightly more coarsescale, dislocation dynamics. Scale transition schemes willhave to be used to translate the conclusions into workablemodels for design applications (see below).(b) Atomistic modellingA promising path is the use of atomistic modelling/moleculardynamics for the study of mechanical properties.Studies are being done on- the behaviour of dislocations in a crystal;- the propagation of a crack in a crystal;- the plastic deformation of nanostructured polycrystallinematerial, when the grain size becomes so small thatdislocation glide no longer is the microscopic deformationmechanisms.MATERIALS PHENOMENA185• How do the phases interact with each other during plasticdeformation?• To what extent is the work hardening pressure dependent?(it might be relevant in cases for which phase transformationsmay contribute to plastic deformation)• Down to which grain size/interlamellar distance woulddislocation glide remain the dominant mechanism ofplastic deformation? By what is it replaced in the verylow nanometre range? How does this affect work hardeningand resistance against crack propagation?• What are the glide systems in phases like cementite,bainite, martensite? What is the values of the criticalresolved shear stresses?• Why can the fracture of cementite upon plastic deformationapparently be avoided in certain materials?• Which phase stresses develop in the various phases, howcan they be measured, how can they be modelled? Howdo they affect ductility and strength?• How is the thermodynamic equilibrium of the variousphases (some of them metastable) affected by the presenceof high stresses and high dislocation densities afterplastic deformation? (important question as to the stabilityin time of properties of a material strengthened bywork hardening).Laser induced thermal shock measurement: influence of extremematerial loading by temperature changes are simulated.(c) Dislocation dynamicsAt a somewhat higher scale (106 atoms), one studies thebehaviour of several hundreds dislocations by using specificmodels for the behaviour of a dislocation in a crystal lattice.This might some day lead to a full understanding of the dislocationpatterns which are observed in deformed materials.(d) Multiscale modellingA successful model at atomistic scale cannot really be usedfor engineering applications. Schemes based on scientificprinciples have to be developed to derive a model whichcan be used at a particular length scale from a model developedfrom a lower length scale. The transition form theatomistic level to the dislocation level, then to the subgrainlevel, then to the grain level, finally to the macroscopic levelwill be achieved in this way during the decade to come.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGARTComputer-Aided Design (CAD)Modelling of tool geometryand time incrementsPreprocessMeshing of materials intofinite elementsFinite element calculationMaterial data baseConstitutive modelof materials186PostprocessFinal shape of product Stress and strain distribution Assessment of formabilityFig. 5.8. Scheme of an FE-software system which can be used to design deep drawing products.5.7.5. Application of Modelling in Design of ComponentsAdvanced high-strength/light weight materials will not beused to reduce weight in cars and other systems unless designprocedures in industries are adapted. This is illustratedby the following example. Suppose that a pressed partof a car (for example, a reinforcement column used for betterprotection of the passengers) is normally made fromlow-carbon steel. By making it from an advanced aluminiumalloy or a high-strength steel, one can reduce thethickness of the plate while maintaining the same strengthbefore fracture. But this would strongly reduce the elasticbending stiffness (this issue has nothing to do with fracture!)if the design is not adapted for the rest. However, itis possible to obtain a sufficient bending stiffness by adequatelyadapting the design. Only, the designers of industryare not familiar with this. Their design principles havebeen optimized by decades of experience with low carbonsteel. Unfortunately, there is no time left to acquire experiencein the same way with the new advanced lightweightmaterials. The answer of materials scientists and researchmanagers to this problem is to modernize the design processby incorporating reliable constitutive models for thematerials behaviour into finite element models for the mechanicalbehaviour of components. This makes it possibleto optimize a product and the production process neededfor it by means of computer-aided design and computeraidedmanufacturing, thereby essentially gaining one ortwo decades in the introduction of advanced lightweightmaterials in industrial applications.Fig. 5.8 illustrates the role of the constitutive model forthe mechanical behaviour of the materials in such system.The state of the art is as follows:• advanced material models which can realisticallydescribe the mechanical behaviour of single-phase polycrystallinematerials (steel, aluminium alloys, copperalloys, -Ti alloys or -Ti alloys) including importantaspects such as texture-based anisotropy and workhardening (also at changing strain paths) are underdevelopment at present.• in the decade to come, it is expected that this work willbe extended to advanced multiphase materials. Thatmeans that all the knowledge acquired by studying thephysical problems listed above (see for example the sectionon multiphase and nano-structured materials)needs to be brought to a level of quality where it can beimplemented in quantitative models. Models of thisquality level will hopefully be transferred from the laboratoriesof universities and research institutions to theindustry during the second decade of the 21 st century.• implementation of advanced non linear model like theseinto FE-codes is a formidable problem by itself. Existingcodes tend to become unstable if realistic materials modelsare used. To solve this problem, the best that theoreticalmechanics can offer is needed. Several leading groupsin the field of FE modelling are now working at this.

5.7.6. Advance of the United States as compared to EuropeA detailed analysis of this issue for all the topics listedabove would require a much longer document. So only themost striking aspects will be given.• “Micro” and “Nano”-technology. The United States arecurrently doing a great research effort, also in the subfieldof “microstructural applications”.The Unites States certainly has an important advantage inthe following fields:• Study of advanced Al- and Ti-alloys and compositematerials. Any institution or company working simultaneouslyon military and civilian applications, and hencehaving access to “military” results for civilian applications,has a great advantage.• Implementation of advanced material models in FEcodes.This work too is strongly supported by the needsof military and nuclear industry.ReferencesThere is no single review paper covering all the topics listed above. Acomplete literature list would be many pages long. So only a few referenceswill be given, to allow for an estimate of the complexity of the issuesdepicted in the present contribution.About work hardening:1. E. Nes, Progress in Materials Science, 41 (1997) 129-194.About advanced FE modelling of polycrystalline materials (work of PaulDawson et al., Cornell University, Ithaca, N.Y., USA):2. P.R. Dawson and A.J. Beaudoin, “Finite element simulation of metalforming”, in “Texture and Anisotropy. Preferred Orientations in Polycrystalsand their Effect on Material Properties,” Kocks, U.F., Tomé, C.N.,Wenk, H.-R., Eds., . Cambridge University Press, Cambridge, U.K. (1998)533-560.MATERIALS PHENOMENA1875.8. Electronic Structure and CorrelationJ. Kirschner, U. Hillebrecht | Max-Planck-Institut für Mikrostrukturphysik, 06120 Halle (Saale), GermanyM. von Löhneysen | Universität Karlsruhe, 76128 Karlsruhe, Germany5.8.1. Present StatusBasic research in materials science includes the study ofelectronic structure as the basis for all properties of materialsemployed in applications. Examples are electricalproperties, magnetism, optical properties, the crystalstructure, etc. Therefore, the study of microscopic electronicproperties complements investigations of macroscopicquantities, which often are aimed directly atimproving specific properties of materials utilized inapplications. Also, the goal of understanding materialsproperties comprehensively by applying variable scalemodelling requires input about electronic structure.Materials whose specific features of the microscopic electronicstructure are employed directly in applications aresemiconductors, superconductors, and magnetic materials.But the electronic structure is also the root of almostany other material property, e.g. the extraordinary mechanicalproperties of some carbides and nitrides, opticalproperties, catalytic activity, etc. Therefore, the study ofelectronic structure both by experimental and theoreticalinvestigations will be of central importance for exploringbasic phenomena, which may lead to novel applications.For the study of electronic structure, there is a broad rangeof highly developed spectroscopic methods available. Themost direct probe of electronic structure is photoemission.This is complemented by techniques such as photoabsorption,linear and non-linear optical spectroscopy,inverse photoemission, etc. Also on the theoretical sideconsiderable progress has been achieved over the lastyears. This includes a higher degree of reliability and precisionwith respect to the ground state electronic structure,not only for simple systems, but also for ever morecomplex materials. Also, the spectroscopic properties,which inevitably involve excited states, can be describedso that in many cases very good agreement is achievedbetween experiment and theory.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART1885.8.2. MagnetismAlthough the d electrons of transition metals are clearlyitinerant, they show in many experiments features oflocalized moments. These two aspects are only starting tobe adequately addressed by introducing realistic modelsfor self-energy effects etc. Magnetic anisotropy, a keyparameter for employing magnetic materials in applications,can be calculated for metallic systems in the bulk.However, in many applications surface anisotropies playa crucial role, so that this capability is being extended tothin films and surfaces, taking the interaction with substratesor neighbouring films in multilayers into account.Magnetic semiconductors, which can be formed by dopingor alloying semiconductors with suitable transitionmetal ions (e.g. Mn to form GaMnAs), have potential applicationsin spin electronics, as they provide a simple wayto combine spin dependent phenomena with conventionalsemiconductor operation. Therefore, the study and developmentof such materials is being vigorously pursuedin the Japan and the U.S. The origin of ferromagnetic orderin systems with low carrier densities and low concentrationof magnetic ions, found both in semiconductingand metallic systems, is presently investigated in manylaboratories.For applications in data storage, the speed of magnetisationreversal is a crucial parameter. Therefore it is of interestto determine the limit for such a process and to possiblyexplore ways to move the limit to faster rates. In thiscontext, the influence of reduced dimension and finitesizes is also of outstanding importance. Dynamic phenomenaare being studied by pump-probe experimentsusing pulsed lasers.Computer technology in the future will probably employnovel devices based on spin dependent transport of carriers.The background is that reduced sizes of structureslead to increased scattering, posing a limit to scaling downthe size of the structures in integrated circuits. It isexpected that such scattering processes will not affect theelectron spin. This suggests that devices based on spindependenttransport may be scaled down to smallerdimensions than conventional electronics. The materialsscience issues for this goal concern the efficient injectionof polarized carriers into the devices, the investigation ofthe spin dependent scattering, which may result in a lossof the spin information, and the development of activedevices (“spin transistors”). Sensors based on spin dependenttransport are already mass-produced as readingheads for disc drives, and their use is expected to increasestrongly. The development of non-volatile memoriesemploying spin dependent transport, which is presentlytaking place, will lead to an important technology withwidespread applications.For magnetic as well as for many other classes of materials,the understanding and possible modification of mesoscopicphenomena is one of the keys for future technologies.As the magnetic units, which contain one bit, become eversmaller, the size of these elements will eventually fallbelow the superparamagnetic limit. This leads to the goalof reaching a better understanding of the properties,which govern this limit, primarily the magnetic anisotropy,in order to tailor or modify them, e.g. by alloying, and/or via the shape of the elements.Levitation of a cylindrical magnet above a high-temperatureYBa 2 CuO 3 superconductor disk cooled to liquid nitrogen (77 K)temperature.All the studies discussed here depend on high qualitypreparation of ultrathin magnetic films and multilayers,including lateral structuring on the nanometre scale, andcharacterization by complementary techniques as discussedin the other sections of this booklet.

5.8.3. Highly Correlated SystemsElectronic correlations in solid materials lead to a narrowingof electronic bands. If the electronic structure isinfluenced by correlations, bandwidths measured e.g. byphotoemission are smaller than calculated by standardtechniques (e.g. local density functional theory). In materialswith strong electronic correlations the properties ofthe itinerant electrons can often be described in terms ofa Fermi liquid where the excitations of the itinerant electronsystem, termed quasiparticles, have a one-to-onecorrespondence to those of the non-interacting electrongas. These quasiparticles carry a renormalized effectivemass, which is usually significantly larger than the massof the free electron. The residual interactions among thequasiparticles are modelled by additional parameters.oxides offer the possibility to modify the physical propertiesover wide ranges by synthesising materials in whichthe oxygen ions – instead of forming complete planes –assemble in smaller units, e.g. chains, ladders, or morecomplicated parquet patterns.5.8.4. TheoryBecause of the increasing complexity of materials forfuture applications, theoretical research will play a vitalrole in the context of material science. In particular, theinfluence of electronic correlations can only be addressedby joint efforts of theoretical and experimental investigations.MATERIALS PHENOMENA189In materials with localized 4f or 5f moments, the exchangeinteraction between the localized moments and the mostlyd-like conduction electrons leads to an indirectexchange interaction between the localized moments ondifferent sites, in most cases favouring antiferromagneticorder. If the interaction is sufficiently strong, a local singlet(Kondo singlet) may arise. These local singlets behaveas extremely heavy quasiparticles.The competition between the Kondo and RKKY interactionsgoverns the behaviour of these materials. The superconductivity,which appears in a number of these systems,appears to be mediated by antiferromagnetic correlationsrather than by phonons. The magnetic moments associatedwith the AF correlations are extremely small, of the orderof 0.01 µ B .The interplay between superconductivity and magnetismis a key feature of high temperature cuprate superconductors.Whereas the symmetry of the order parameter hasbeen established, a number of questions remain unanswered.An important issue is whether spatial correlationsof charge carriers (so-called stripes) do exist and what rolethey play for superconductivity. Also, the origin of the manyunusual properties in the normal state of the cuprates isnot fully understood. An example is the “smeared” energygap (‘pseudo gap’) appearing in many properties.The manganites are structurally related to the cupratesuperconductors, both belonging to the class of Perovskitestructures. Although known for a long time, these materialsare now being studied intensively because of thehigh potential for applications arising from the so-calledcolossal magnetoresistance (CMR) effect. In these materialsthe interplay between magnetic, charge and orbitalordering governs the physical properties. Transition metalA major contributing factor to the successes of solid statetheory during the last years have been calculations basedon the local density approximation (LDA). It allows totreat a broad range of materials, from semiconductors tosimple and transition metals, to molecular solids etc. Fullyrelativistic calculations are now possible to a precision,which allows understanding e.g. magnetic anisotropiesor the occurrence of different crystalline phases from amicroscopic point of view. Therefore, solid state theoryusing this approach will remain a valuable tool for materialsscience.However, there are some aspects, which are not satisfactorilyaddressed by LDA theory. To reproduce the magnitudeof band gaps in semiconductors requires the introductionof self-energy corrections. The situation is evenmore severe for compounds with highly localized valencestates, such as oxides. Even though introduction of Coulombcorrelation U (abbreviated LDA+U) provides asomewhat better description of such systems, the basicproblem of treating the Coulomb correlations comparableto bandwidths remains unsolved. Present dayapproaches start either from a localized or a band likepicture, and introduce other features as corrections, e.g.by perturbative concepts.As many aspects of electron correlation are very similar inmolecules and solids, the question arises as to whether itis not possible to transfer concepts between the two areasin order to make progress in the treatment of electroniccorrelations. The difficulty encountered is that the waysof treating correlations in small molecules cannot becarried over to solids, in particular for highly localizedelectrons. Future work should be aimed at overcomingthese difficulties, for which ways have been proposed,or to develop novel concepts. Many interesting new ma-

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART190terials show strong electronic correlations. To achievea satisfactory description of such materials, models haveto include the dominant parts of the electron-electroninteractions from the start, whereby any theoreticaldescription loses its single particle form. Other importantaspects concern the influence of reduced dimensionalityon physical properties (mesoscopic phenomena).5.8.5 . Expected Trends during the Next YearsIn U.S., Japan, and Europe there is a broad effort underway to utilize novel phenomena related to electronic structure(in magnetism, superconductivity, etc) for technicalapplications. This concerns giant magnetoresistance(already used for data storage, but other applications arevigorously pursued), tunnelling magnetoresistance,colossal magnetoresistance (manganites), high T c materials,and combination of these with each other as wellas with existing semiconductor technology. The highpotential of new phenomena based on controlled manufacturingof thin films is manifest in the announcement ofa joint effort of two major companies (IBM and Infineon)to develop novel magnetic random access memories(MRAM’s) within the next 4-5 years.In Europe, the area of heavy Fermion systems and weakitinerant ferromagnets is studied by very active groups.With regard to high temperature superconductors (highTc cuprates), giant magnetoresistance (GMR) and colossalmagnetoresistance (CMR) in magnetic multilayersand manganites, respectively, the original discoveries weremade in Europe. However, activities in the U.S. havegrown very strongly in these fields, so that in the futureefforts should be made to maintain a competitive positionof the European groups.The so-called colossal magnetoresistance materials areattractive for applications because of the large change ofthe resistance. Basic materials research in this field aimsto clarify the underlying physical mechanisms, with thegoal of achieving large resistance changes with fieldswhich can be reached in possible device applications.In many fields future efforts will be directed towards developingphenomena which may reproducible and wellunderstood for narrowly defined, idealized experimental(laboratory) conditions, but need to be extended to widerrange of conditions (temperature, pressure, long termstability, etc.) to be useful in applications.5.8.6. Suggested Measures to be taken by EUMaterials research will be one of the keys to new technologiesin the future. To maintain the high level of excellencewhich has been the achieved in Europe in this area, and toensure competitiveness in the future, the EU programmesshould vigorously support materials research dedicated tounderstand, develop (improve, optimize) and manipulate(tailor) novel phenomena. This includes among others:Research on heterostructures: ferro-/non-ferromagnetic,ferromagnetic/semiconductor, oxide-metal interfaces;search for magnetoresistive (GMR, CMR) materials withsharp transitions in small fields at room temperature; spininjection and transport in ferromagnetic/semiconductorstructures; synthesis and study of magnetic semiconductorsshowing ferromagnetic order (GaMnAs and relatedmaterials); semimetallic materials; high T c superconductorsand other highly correlated electron systems; micromagnetism,influence of (nano)structuring on properties,superparamagnetic limit, magnetic anisotropy.Understanding magnetic phenomena on a microscopiclevel requires advanced analytical techniques, e.g. electronspectroscopies (spin resolution at high-energyresolution, spatial resolution, and time resolution toinvestigate switching and other dynamical phenomena).Methods for detailed study of spin structures should bedeveloped further, as well as techniques to tailor these forspecific needs. Advanced microscopic techniques shouldSolidification structure as obtained by computer simulations.

e developed further to incorporate different contrastmechanisms for the analysis of increasingly complexnanostructured materials. The influence of reduceddimensions on the spin structure both in ferro- andantiferromagnetic materials is important for the basicunderstanding as well as for applications, and should bestudied experimentally as well as theoretically.In most applications, materials will be employed in theform of thin films. Therefore, surface and interface propertiesneed to be understood and controlled. This requiresthat studies of bulk properties are complemented by controlledsurface and interface preparation and analysis. Inaddition, special techniques are needed for the analysisof buried interfaces and nanostructured materials.Dynamic studies of electronic properties, e.g. by usingpulsed lasers, are highly desirable. In addition, the timestructure inherent to synchrotron radiation offers attractivepossibilities for time resolved studies. Also, the use of(soft) X-rays allows differentiating between different componentsin multilayers or composite materials. Expectedpulse widths of the order of 100 fs for projected Free ElectronLasers (e.g. at Hasylab, Hamburg) offer the route toextend these studies to regimes not accessible until now.Use of these unique possibilities should be supported.In order clarify the similarities and differences in thedifferent classes of strongly correlated materials, researchshould be extended to more systems showing Fermiliquid instabilities. Microscopic probes such as neutronscattering, probing the short range fluctuations, andmuon spin rotation for determining very small magneticmoments should performed, complemented by macroscopicmeasurements covering extreme conditions, e.g.ultra-low temperatures and high pressures. The studyof the influence of substitutions on magnetic and nonmagneticsites in stoichiometric compounds will providemore insight on the (non-) Fermi liquid behaviour of thesematerials.On the theoretical side, calculations of the electronicstructure of diverse materials will be needed in the futureto understand and direct experimental studies. Localdensity functional theory is adequate for many systems ofinterest, and will remain the prime method to characterisethe electronic structure of materials theoretically,at least as a starting point. At the same time, new conceptsshould be developed to handle highly correlated materials.Many systems of future interest will be non-metallic(oxides, semiconductors), which because of the highdegree of electronic correlation are beyond presentmodels, and therefore require refined or even completelynovel approaches. To obtain better descriptions of suchhighly correlated materials, future work should be aimedat incorporating electronic correlations form the start,rather than adding these effects later. Novel schemes toincorporate the effect of self-energy should be developedfurther.Despite considerable progress over the last years, it is stillnot possible to reliably predict the magnetic transitiontemperatures of ultrathin magnetic films and alloys. Magneticanisotropy of highly localized compounds and theirinterfaces is also an issue of increasing importance. Theseissues should be addressed by theoretical work. The stateof art is even less developed for antiferromagnetic andferrimagnetic systems.Theoretical models usually deal with idealized situations,which are difficult or impossible to realize experimentally,and much more so for technical applications. Therefore itis desirable to extend theoretical studies to incorporatedefects and/or impurities in the bulk and at interfaces, tofacilitate comparison to experimental data obtained fromnon-ideal materials. One of the strengths of Europeanscience is the generally close collaboration of experimentalistsand theorists. This should also be the practice inthe projects funded by the European Commission.MATERIALS PHENOMENA191Materials science requires the preparation of good materials.Therefore a concerted effort should be envisaged tosupport the best possible facilities for preparation andcharacterization of new materials, as well as efforts toprepare ‘known’ materials with better properties. Thisincludes also preparation and characterisation of microandnanostructured systems e.g. by self-organization,e-beam lithography, scanning probe techniques, or othermethods.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGARTConclusionsThe number and variety of phenomena displayed by materialsare vast, ranging from physical and mechanical phenomenato thermal effects, electronic, optical and magnetic phenomena.Far from equilibrium, complex materials are usednowadays in real applications. We are only beginning tounderstand the role of the key parameters. Such understandingmust increase in the future if we are to design materialswith specific properties from the atomic scale upwards. Itcan be concluded that:• Interface modelling cannot be achieved on the basis of geometrical/crystallographicalconcepts alone: transformationconstraints, as invariant plane strain, have to be identifiedand incorporated.• Especially research on interface mobilities has to be promoted.Such work may in particular throw light on the couplingof the thermodynamical driving force to the transformationkinetics.192• Many new phenomena still await to be discovered and to beput on a theoretical basis.• Understanding of dynamical, non-equilibrium aspects ofcomplex systems (from quantum effects to fracture) is a prerequisite.The microstructure of a material (crystalline or amorphous;metallic, inorganic, ceramic, organic or biological (living))controls its properties. There is a strong need to describechanges of the microstructure of materials on the basis ofmodels for the kinetics of material behaviour. Only thus materialproperties can be optimized. The present state ofknowledge does not allow sufficiently accurate modelling of(transformation/reaction) kinetics. In particular:• A distinctly improved understanding of nucleation (of newphases) is imperative.In forthcoming years undoubtedly the technological importanceof thin film systems and nanomaterials will increasestill; one could say: the area of minituarization will end onlywith the emergence of single electron/molecule transistors.Consequently, the interfaces (grain/interphase boundaries)and surfaces may largely dictate the properties of small scalestructures. Within this context it has been recognized thatthere is a lack of basic, fundamental understanding of materialsphenomena, that will obstruct further, successful applicationsof thin films and nanomaterials. In this case certainaspects of both material statics and material dynamicsdeserve special interest:• Data and models for interfacial energies have to be acquiredand developed, respectively, in particular for many systems ofpractical interest.An activity of growing importance will be the understandingof the interface of inorganic/metallic material with biologicalmaterials. Developments in medical and biological technologynecessitate this research.Small size systems can suffer greatly from lack of stabilitydue to the presence or occurrence of internal stresses. Alsoagainst this background, fundamental interest in the consequencesof internal stress for material behaviour has grown:• An emphasis of research must be on the role of internal(residual) stress in material behaviour.Knowledge of materials phenomena on a local (say, atomic)scale by itself does not suffice at all to understand and thuspredict material properties of specimens/workpieces on amacroscopic scale:• Models for bridging length scales (e.g. for crystalline materials:atom –> domain –> grain –> macroscopic aggregate ofgrains) have to be developed.A well known distinction between materials can be made inview of their application: structural materials, i.e. materialswith load bearing capacity, for which the mechanical propertiesare of cardinal importance, and functional materials, i.e.materials with electrical, magnetic or optical properties ofdirect use. Microstructural control is the key to their successfulapplication and research in this direction should beencouraged. Thus, development of nanostructured pearliticsteels, i.e. with a very small lamellar distance, could causesuperior mechanical properties. Or, control of speed of magnetizationreversal in structures of materials of small andsmaller becoming dimensions ((laterally structured) thinfilms and multilayers), used for data storage, requires fundamentalunderstanding of the role of the size parameters.

Understanding of composites and hybrid materials will bedeveloped to exploit new phenomena for a range of applicationsfrom artificial bones to smart materials. Self-repair,environmental sensing and novel electronic, optical and magneticphenomena are some of the possibilities that couldarise from combinations of inorganic/metallic materials andorganic/biological materials.The richness of phenomena exhibited by colloidal systemsand solutions needs to be investigated and exploited for thesynthesis of materials that are both environmentally benignand superior in performance. Colloidal chemistry is a keytechnology for fabricating nanostructured, self-replicatingand self-assembly materials that will revolutionize the waywe manufacture and use materials.improved interaction between the scientists involved in thecentre. Also, the experimental methods in which one institutionexcels then become available to the whole communityin the centre. It would also be advantageous if in such avirtual centre an effort would be made to cross the bordersbetween material classes (e.g. metals and polymers), as thesearch for unifying concepts for material phenomena shouldbe a focal point of the research activity of the centre.Finally, Europe should do everything it can to attract moreyoung people for an academic materials science study, inparticular a PhD study. The current situation is disastrous.For maintaining, let alone improving, the competitiveness ofEurope in basic materials science, this can be as importantas the direct funding of this research.MATERIALS PHENOMENA193The increasing complexity of materials used in practice (see,for instance, immediately above) requires the availability ofmodels to predict their properties, since it is impossible toenlarge the measured data set of material properties infinitely.Yet, even sophisticated models of this kind require theavailability of data sets, for example for boundary, more simplesystems, from which successful “extrapolations” can bemade. Here one can point at the experimental databases ofthermodynamic parameters. The work on these databases isessential for materials science, but its importance is underestimatedand certainly not well appreciated. Hence:• Data base development, maintenance and linkage should bea coordinated effort and have top priority within the materialsscience community.In the field of materials science in recent years research ofapplied character has been growing at the cost of research offundamental character. It is important that basic research onthe underlying physical and chemical causes of materialsbehaviour be invigorated so that we gain sufficient understandingto create the next generation of improved materials.Therefore,• Basic, fundamental research on materials phenomena shouldbe promoted.A possible European centre of excellence on basic materialsscience can be crucial for the advancement of fundamentalunderstanding of materials behaviour. Because top levelexpertise is available at various places in Europe and noexisting centre could claim to offer the highest expertise inall areas, it seems appropriate to strive for a virtual centreby linking the top places in Europe. This type of networkingcan stimulate the progress of understanding enormously by

CHAPTER 66. MATERIALS SYNTHESISAND PROCESSING194195The public at large, confronted with end productsbased on materials, is largely ignorant of the importanceof the necessary processing of the materialson which the product is based. Seldom, also, does it realizethe enormous benefits that can result from advancesin the processing of materials. Indeed, the costs of materialsprocessing are usually very much larger than the costsof the synthesis of the raw material components. Thus,having knowledge of favourable intrinsic properties ofa component (compound) is only the first step in a longdevelopment process leading to a successful, practically(i.e. also commercially) important processing route.Introductionclaim that in the following the processing aspects of allcurrent materials classes of significance have been dealtwith extensively. Instead, the focus is on those aspects ofmaterials processing which, with certainty, can be consideredto be very relevant currently and which at the sametime reveal the general situation and problems associatedwith materials processing in the European research area.On this basis some general conclusions can be formulatedin a reviewing section at the end of this chapter.Metals were and are still the most important class of materials.Therefore, it is appropriate here to refer to the originallyseemingly magical role of the blacksmith in the historyof mankind: by using heat and mechanical deformationfavourable properties were generated for a workpiecemade of a material we (now) call steel. This example servesto illustrate that at least originally the development ofknowledge on which a materials processing technology isbased was acquired in a phenomenological way, i.e. bychance. Whether the situation has improved may bejudged on inspection of the contributions in this chapter.Nowadays many classes of material are manufactured.Although we have striven for a broad coverage, we cannot▲Surface of a molten Si sample (optical micrograph obtained usinginterference contrast, G. Kiessler, MPI für Metallforschung Stuttgart).

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART1966.1. Thin Film ScienceT. Wagner | Max-Planck-Institut für Metallforschung, 70174 Stuttgart, Germany6.1.1. IntroductionIn recent years, thin film science has grown world-wide intoa major research area. The importance of coatings and thesynthesis of new materials for industry have resulted in atremendous increase of innovative thin film processing technologies.Currently, this development goes hand-in-handwith the explosion of scientific and technological breakthroughsin microelectronics, optics and nanotechnology[1]. A second major field comprises process technologies forfilms with thicknesses ranging from one to several microns.These films are essential for a multitude of production areas,such as thermal barrier coatings and wear protections,enhancing service life of tools and to protect materialsagainst thermal and atmospheric influences [2, 3]. Presently,rapidly changing needs for thin film materials anddevices are creating new opportunities for the developmentof new processes, materials and technologies (Fig. 6.1).New PatterningTechniquesElements of Thin Film ScienceIn situCharacterizationNew physicalPropertiesNew MaterialsThin FilmScienceTailoring ofMicrostructureTailoring ofInterface - SurfaceImprovedChemical StabilityNew ProcessingTechniquesFig. 6.1. New processing techniques related to thin film materials anddevices.Therefore, basic research activities will be necessary inthe future, to increase knowledge, understanding, and todevelop predictive capabilities for relating fundamentalphysical and chemical properties to the microstructureand performance of thin films in various applications. Inbasic research, special model systems are needed for quantitativeinvestigations of the relevant and fundamental processesin thin film materials science. In particular, thesemodel systems enable the investigation of i.e. nucleationand growth processes, solid state reactions, the thermaland mechanical stability of thin film systems and phaseboundaries. Results of combined experimental and theoreticalinvestigations are a prerequisite for the developmentof new thin film systems and the tailoring of theirmicrostructure and performance.6.1.2. State of the ArtThe major exploitation of thin film science is still in thefield of microelectronics. However, there are growing applicationsin other areas like thin films for optical and magneticdevices, electrochemistry, protective and decorativecoatings and catalysis. Most features of these thin filmactivities are represented by a relatively new research area,called surface engineering [2]. Surface engineering has beenone of the most expanding scientific areas in the last 10years and includes the design and processing of surfacelayers and coatings, internal interfaces and their characterization.Surface engineering is directed by the demandsof thin film and surface characteristics of materials.(a) Thin film processing techniquesThere exists a huge variety of thin film deposition processesand technologies which originate from purely physicalor purely chemical processes. The more important thinfilm processes are based on liquid phase chemical techniques,gas phase chemical processes, glow discharge processesand evaporation methods [4]. Recently, a considerablenumber of novel processes that utilize a combinationof different processes have been developed. This combinationallows a more defined control and tailoring of themicrostructure and properties of thin films. Typical processesare e.g. ion beam assisted deposition (IBAD) andplasma enhanced CVD (PECVD). Examples for novel thinfilm processing techniques, which are still under development,are pulsed laser ablation (PLD) and chemical solutiondeposition (CSD). Both techniques enable the synthesisof complex thin film materials (complex oxides, carbides,and nitrides).

Presently, experimental efforts are increasingly supportedby computational approaches that address complex growthprocesses, saving time and money. These approachesenable e.g. the description of the evolution of thin filmmicrostructures as a function of processing parameters.(b) In situ characterizationThe thin film process equipment can be categorized intoproduction equipment for device manufacturing, equipmentfor research and development, and prototype apparatusfor fundamental investigations of new or establisheddeposition processes. One reason for the world-wide rapidgrowth of deposition technology is that equipment manufacturershave successfully met the demands for moresophisticated deposition systems including in situ characterization(e.g. reflection high-energy electron diffraction(RHEED), scanning probe microscopy (SPM)) and processmonitoring techniques for measuring process parametersand film properties (e. g. ellipsometry, plasma analysistechniques). Novel experimental tools have enableddiscoveries of a variety of new phenomena at the nanoscalewhich have in turn opened unexpected opportunitiesfor the development of thin film systems, and tremendousprogress regarding a fundamental understanding of therespective technological processes has been made.(c) New materialsThin film systems necessitate direct control of materialson the molecular and atomic scale, including surface modifications,deposition and structuring. Many of these techniqueswere improved during the last decade, resulting inremarkable advances in the fundamental understandingof the physics and chemistry of thin films, their microstructuralevolution and their properties. This progress hasled to the development of new materials, expanded applicationsand new designs of devices and functional thin filmsystems. One of the most outstanding examples is the successfuldevelopment of semiconductor devices with novelmaterials like oxides and nitrides (e.g. GaN). Other typicalexamples are advances in the synthesis of hard coatingsbased on borides, carbides and nitrides [3].and the thermal and environmental stability of thin filmsystems. Future developments are critical to overcomingobstacles to miniaturization as feature sizes in devicesreach the nanoscale. Basic research in this field will referto developments of experimental tools necessary to in situcharacterize and measure thin film structures (e.g. opticaland magnetic characterization), and developments ofnovel techniques for synthesis and design. These techniquesmay be more reliable, less expensive, or capable ofproducing films with new or improved properties. Typicalexamples are chemical solution deposition (CSD), includinghydrothermal approaches, biomimetic pathways forassembling inorganic thin films, or device applications ofliquid crystalline polymer films [5].Experiments alone will be insufficient. Theory and modellingare essential for a complete understanding of the fundamentalgrowth and deposition processes. Multiscalemodelling of thin film and nanostructuring processes willbe an absolute necessity in the next decade in order toutilize the tremendous potential of thin film science andtechnology. It is expected that time consuming and expensiveexperiments will be replaced by theory and modelling.Especially, it is still necessary to develop a fundamentalunderstanding of the decisive growth and deposition processes.It will be important for research institutes to focuson the development of fundamental and novel processesand devices. This will only be realized if a more definedconnection of the activities between single researchgroups and industry can be achieved, based on a fluentexchange of information. Research institutes and companies,which cannot achieve this, will have difficulty competingin future. In this field, Europe must compete directlywith the U.S. and Japan. In comparison to Europe,there appears to exist an advantageous research environmentin the U.S. and Japan, which supports a more fluentconversion of results from basic research into applications.This could be balanced in Europe by improvednetworking between industry and research laboratories inthe field of basic research.MATERIALS SYNTHESIS AND PROCESSING1976.1.3. Expectations 2000 –2010The gap between solving fundamental materials problemsand developing new thin film devices for microelectronicand nanotechnological applications is quickly increasing.For example, in many applications the development of thinfilm systems is accompanied by a variety of materials andprocessing problems, which require extensive futureefforts to be solved. Prominent examples are the adhesion6.1.4. Expected Needs 2000 –2010(a) InitiativesEmphasis should be placed on future developments of filmdeposition processes for application in advanced microelectronicdevice and nanotechnology applications thatrequire the most demanding approaches. Surface engineeringis a second important field where similar demandshave to be fulfilled. Effective development of thin film

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART198systems can only be realized if the fundamental processsteps are well understood. For the future advancement ofthin film research and technology, the following endeavorsare prerequisite:• Development of improved and novel thin film processtechnologies and design methodologies• Development of new materials• More fundamental understanding of the relationshipsbetween microstructure and properties, and how thesecan be tailored• Improvement and automation of in situ characterizationtools with high spatial resolution and chemical sensitivity• Strong networking between research laboratories andindustry in Europe, and materials research centres inEurope, U.S. and Japan• Establishment of special competence centresIn the following, some examples are given where new processesand technologies will challenge established procedures:(b) Thin film model systemsDeposition processes for applications in advanced microelectronicsand surface engineering processes will requirethe most demanding approaches in the near future. Newconcepts and design methodologies are needed to createand synthesize new thin film devices and to integrate theminto architectures for various operations. Examples are thecontrol of surface processes, the development of computermemory chips, and the production of two- and three-dimensionalnanostructures. There will be a rapid increasein the significance of basic research projects due to the needof new materials and devices in these fields. Therefore,purposeful future developments and an understanding ofthe versatility of the basic deposition processes is needed,including microstructural evolution of thin films, e.g. substrateand surface preparation, nucleation and growth. Forthe realization of thin film systems, it is of future interestto understand the critical role of surfaces and interfaces.We need to know the structure and bonding at heterophaseinterfaces and grain boundaries, and we have to understandhow to produce special interfaces experimentallyand how to tailor them for specific properties. Additionally,the thermal, chemical and structural stability of the thinfilm systems and devices need to be investigated thoroughlyto allow for the adaptation of fundamental processes. Toinitiate all these processes, special model systems have tobe synthesized and studied experimentally and theoretically(Fig. 6.2).Typical examples are:• metal and ceramic multilayers• functionally graded thin films• growth of metastable phase layers• super hard thin films• nanocrystalline layers• superlattice thin films• composite coatingsThin Film Model SystemsThin FilmnoChemical reactions• material properties• growth parametersyesAtomically abrupt interfacesInterfacial phases and/orinterdiffusionPhysical propertiesBondingTranslation stateInterfacial defectsKineticsof reactionsThermodynamicsof reactionsDegree of coherency;misfit dislocationsTheoreticalcalculationsFig. 6.2. Research areas for thin film systems.

Significant improvement in both, theory and modellingare necessary to help direct the developments in thin filmscience and technology. This is one of the most promisingattempts for accelerating future developments.(c) The development of new materials: a combinatorialapproachAn accommodation of the equipment to the research anddevelopment of new device structures and materials withnew properties must be performed continuously. For example,research and development equipment has to offera high degree of flexibility in the accommodation of a multitudeof substrates, in deposition parameters, and in realtime monitoring capability. Until recently, these facilitiesdid not facilitate a high product throughput, which madethe development of new thin film materials rather tedious.By using a combinatorial approach, parallel thin film processingcan be realized, and by significantly reducing samplesize, time and money can be saved (Fig. 6.3).This requires the development of new and complex depositionsystems. For example, this can be realized by usingmasks with different patterns in front of the substrate.Then, single or/and multi-beam deposition will result inparallel thin film processing. As a result, the substrate willconsist of thin film patches with varying chemical composition.However, miniaturization complicates the processingprocedures, and thus an improvement in the resolutionof typical thin film characterization tools will be ofgreat importance. Full automation of the deposition andcharacterization routines is required here (e.g. automaticshutter and temperature control, scanning beam RHEEDsystems). A further advantage of the combinatorial approachis the fast characterization of the deposition processand the system itself. Worldwide, the developmentsof these processes are still in the initial stages. Presently inEurope, projects of combinatorial chemistry are supportedin the field of chemical technologies. These researchprogrammes should be extended to all fields of new technologies,which depend on thin film science, and technology,and it is important to realize these projects in Europethrough networks which consist of research centres andindustry.Chemical Solution DepositionPrecursor SynthesisMATERIALS SYNTHESIS AND PROCESSING199Thin Film Deposition: A Combinatorial ApproachGrowthChamberSubstrateSubstrateMaskVaporTarget MaterialsLaser BeamViewport1. deposition step 2. deposition step 3. deposition step Thin Films n. deposition stepFig. 6.3. A combinatorial approach for parallel thin film processing.Spin CoatingPyrolysis at ElevatedTemperaturesFig. 6.4. The chemical solution deposition method for the production ofepitaxial inorganic thin films.(d) Thin film systems via chemical solution deposition(CSD) Conventional CVD and PVD processes are usedroutinely to synthesize thin film systems. Such processtechnologies are rather complex and expensive [4]. Dependingon the applications, these films have to fulfilspecial demands and very often, low defect densities arenecessary. For most applications, one would prefer filmswith which have a special texture, low grain boundary density,and smooth surfaces. Epitaxial films fulfil these requirements.Very promising approaches to synthesis inorganicsingle crystalline thin films are chemical solutiondeposition method (CSD) (Fig. 6.4) and related processes.CSD enables the growth of thin films fom solutions, eitheraqueous or organic [6]. These solutions contain precursormolecules for a variety of elements in the thin film of interest.CSD is inexpensive and enables the synthesis of thinfilm materials with complex chemical compositions. Themain advantage of CSD is the high degree of compositionalcontrol, inherent with other solution synthesis routesfor multi-element, inorganic materials. Recently, singlecrystalline carbide and nitride thin films were synthesizedvia CSD. CSD will become one of the key technologies tosynthesize epitaxial oxide, nitride and carbide films for a

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART200variety of different applications, e.g. opto-electronic deviceapplications, hard coatings and dielectric thin films.A further advantage of CSD will be thepossibility of direct patterning of thin films via stampingtechniques. However, for these purposes, appropriateprecursor solutions have to be synthesized in future. Onebig challenge is the synthesis of precursor materials withwell-defined doping levels for thin film applications inelectronic devices.(e) Manpower, interdisciplinary researchContinued progress in thin film research seems to be increasinglydependent upon collaborative efforts amongseveral different disciplines, as well as closer coordinationamong funding agencies and effective partnerships includingresearch laboratories, universities, and industry. Recently,a variety of different interdisciplinary programmesfor nanotechnology and microelectronics were initiated inthe U.S., Japan and Europe. However, the topic of thinfilm science and technology is automatically included insuch programmes, although it would be of great benefit toestablish individual programmes, which focus on majorthin film activities in Europe. Interdisciplinary programmesof combinatorial materials science and technology of thinfilms and surface engineering are necessary, to promote theformation of fundamental associations for the improvementand development of new techniques, and of novelmaterials and their properties.The university education of researchers working in the thinfilm area would benefit from an interdisciplinary approach.The materials problems in thin films research are very complexand require interdisciplinary training, that is, a combinationof studies including physics, chemistry, engineering,materials science and biology. In comparison to Europeand Japan, the U.S. seems to occupy a leading positionin this field. In the future, efforts should be taken to compensatefor this deficit in Europe by modifying the educationsystem in such a way that new training directions areincluded, helping to create a new generation of researcherswho work across traditional disciplines. This task maybe supported by new centres of excellence in the field ofthin film science and technology.Thin film process techniques and research are stronglyrelated to the basic research activities in nanotechnology.Thus, government expenditures on nanotechnologyresearch are a reliable indicator of the budget for thin filmresearch. The government expenditures for nanotechnologyresearch are presently at similar levels in the U.S.,Japan and Western Europe, suggesting that the respectivequantities of research activity are comparable. Accordingto a WTEC study in 1997 [1], large companies in Japanand the U.S. contribute to research to a greater extend thando their counterparts in Europe. While large multinationalcompanies are developing nanotechnology researchactivities worldwide, the transfer of new processes to themarket is strongest in the U.S. In Western Europe, adiverse combination of university research, networks andnational laboratories with a special emphasis on coatingsis active. The largest funding opportunities for nanotechnologyare provided by the NSF in the U.S., by MITI inJapan and by BMBF in Germany. Categories such as physicaland chemical technologies, materials research, microsystemtechnologies, electronics and nanotechnologiesare supported by BMBF. Common features of these disciplinesare projects which are located in the area of thinfilm research. In the case of nanotechnology, the BMBFhas established several centres of competence with emphasison such topics as opto-electronics, nano-analytics,and ultra-thin films. Ultra-thin films are among the mainelements of thin film science that have varied applicationsin optics, microelectronics and wear protection.References1. WTEC Panel Report on R & D Status and Trends in Nanoparticles, NanostructuredMaterials, and Nanodevices, R. W. Siegel, E. H. Hu, M. C. Roco,Workshop 1997 (http://itri.loyola.edu/nano/us_r_n_d/toc.htm)2. Surface Engineering, Science and Technology I, Editors : A. Kumar, Y.-W.Chung, J. J. Moore, J. E. Smugeresky, The Minerals, Metals &MaterialsSociety, Warrendale, 1999.3. Hard Coatings, Edited by A. Kumar, Y.-W. Chung, R. W. J. Chia, The Minerals,Metals & Materials Society, Warrendale, 1998.4. Handbook of Thin Film Process Technology, Editors: D. A. Glocker and S.I. Shah, Institute of Physics Publishing, Bristol and Philadelphia, 1998.5. Thin Films, Science 273 (1996).6. F. F. Lange, Science 273 (1996) 903.6.1.5. Expenditures

6.2. Synthesis and Processing of Inorganic MaterialsJ. Etourneau | Institut de chimie de matière condensée de Bordeaux, 33608 Pessac Cedex, FranceA. Fuertes | Instituto de Ciencia de Materiales de Barcelona, SpainM. Jansen | Max-Planck-Institut für Festkörperforschung, 70569 Stuttgart, Germany6.2.1. IntroductionFundamental to the success of materials science and technologyis the availability of high-quality materials exhibitingspecific tailor-made properties together with an appropriateshape and microstructure. Let us mention that most of theinorganic materials of current interests have been discoveredby chance and it is obvious that there is a conscious effortat present to rationally design inorganic materials basedon chemical principles. Although there is a steady progressin solid state chemistry there still exists a serious deficit inthe ability to produce materials with desired intrinsic propertiesby both rational design and synthesis. This remark isalso valid for the generation of specific nanostructures, microstructuresand shapes, which, eventually, determine theoverall performance of a workpiece within a device.6.2.2. State of the ArtThe most important synthetic methods that have been recentlydeveloped are molecular templating, synthesisunder extreme conditions of pressure and temperature,self-assembly, soft chemistry, electrochemistry, low temperatureflux and hydrothermal methods, and the robotassistedcombinatorial synthesis. Most of these new syntheticmethods have been essential to allow the isolation ofmetastable phases with relevant properties. On the otherhand, the extraordinary progress in the implementation ofsophisticated characterization techniques for the determinationof the local chemical composition, texture, microstructure,crystal, electronic, phonon and magnetic structures,has allowed the establishment of precise relationshipsbetween crystal chemical parameters, local structureand physical properties. Both, synthesis and compositionstructure-propertyrelationships, constitute the feedbackfor the design of new materials for future needs.However, despite great advances in probing the structuresof solids and measurements of their physical properties,the design and synthesis of inorganic solids possessing desiredstructures and properties remain a challenge todayin both volume and surface dominated materials and incomplex systems (Fig. 6.5).Planning a solid state synthesis rationally includes twobasic steps: the prediction of compounds capable of existence,and the design of viable routes for their synthesis.Ideally, one would like to construct a solid compound accordingto a given requirement profile, and subsequentlyoutline the synthetic route that will produce exactly therequired substance. Both these steps are non-trivialbecause we are not only unable to predict definitely thestructure, stability and properties of solid inorganic compoundsfrom first principles, but also we do not know theright method to synthesize the solid even if we have guessedthe desired composition. However, an approach towardsrational synthesis of inorganic solids could be based on theinvestigation of the energy landscape of the chemicalsystem using quantum mechanical calculations togetherwith a full understanding of underlying principles of chemicalsyntheses. Implementing such an approach is still fartoo difficult, however, and current investigations usuallyemploy a stepping-stone approach by splitting the task intosolvable sub-problems using appropriate approximationsalong the way. First, a global search of the energy landscapeconstructed from simplified energy functions determineslocally ergodic regions, e.g. local minima of thepotential energy, which are surrounded by sufficiently highenergetic and entropic barriers. These regions correspondto kinetically stable structure candidates, which are thenrefined on a quantum mechanical level with local optimizationmethods. In a third step, the properties of these(meta)stable compounds are computed using appropriatealgorithms. Finally, a synthesis route for those materialswith desired properties is constructed. Besides pointingout the way towards new goals in fundamental and appliedchemistry, this study of energy landscapes of chemicalsystems can assist in the calculation, evaluation and improvementof phase diagrams, by e.g. suggesting possiblemodifications that exist in synthetically inaccessibleregions in the thermodynamic parameter space. Thesewould provide important input data for programmesystems like CALPHAD.Combinatorial chemistry takes its name from a techniquein molecular chemistry, where a large number of differentmolecular building units are placed into solution, allowingthe parallel synthesis of essentially all possible combinationsof these units. Analogously, many solid state reac-MATERIALS SYNTHESIS AND PROCESSING201

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGARTAt the BottomTo Nanomaterials(Conference of R. Feynmanat the APS 1959)Synthesis and Processing of Inorganic MaterialsThe Function defines the MaterialFor Materials there is plenty of RoomPresentandFutureMaterials by Design and Rational SynthesisAt the TopTo Complex Systems viaSelf-Assembly(e.g. Hybrid Organic-Inorganic Solids)202Search for new Materials from• Prediction of chemicalCompositions and Structures(First principles Methods)• Combinatorial Chemistry(Identification of new Materials)Dominated Surface MaterialsNanomaterials• Powders• Densed andMicroporous Solids• Thin Films• Glasses• Composites• Gels and Colloids• Single CrystalsSearch for new Adapted Synthesisand Processing leading to Control of• Deffects• Microstructures• Nanostructures• Self Assembly (Building Blocks)Dominated Volume MaterialsMaterials Assembly in DevicesChemical CompatibilityThermomechanical EffectsFig. 6.5. Overview of the synthesis and processing of inorganic materials.tions are allowed to take place in parallel, spread out over aplanar surface, e.g. by thin film deposition combined withmultiple masking techniques, or by the solution-phasemethod employing scanning inkjet techniques. This resultsin a miniaturization, parallelization and automation of thesynthesis. However, since each such a reaction takes placein isolation, for different but fixed compositions, the term« high throughput synthesis » might actually be moreappropriate.The control and the prediction of both textures and microstructuresof inorganic materials are crucial for macroscopicproperties and industrial applications. When dealingwith real systems, non-periodic imperfections play an importantrole, ranging from defects in single crystals overlarger (multi-crystalline) systems containing grain boundariesto macroscopic interfaces and surfaces and finallyamorphous compounds, both as film and bulk. Thesetextures and microstructures may occur by accident ordesign, but the computational resources are usually notsufficient to deal with them from first principles. Thustheir description has required the development of variousapproximations, and semi-empirical and phenomenologicalmodels. Usually, the validity of the individual model orapproximation is based on the applicability of a separationof time scales, which often translates into a separation onspatial scales. The actual simulations range from quantummechanical calculations over classical simulations withempirical potentials to finite element methods in continuummechanics.Concerning the status of experimental work, currently,mostly physical techniques like e.g. thin- and thick filmMBE combined with etching procedures are used whengoing beyond the crystalline state to achieve specific mesoscopictextures.

Currently, the EU countries, in particular France and Germany,possess an especially high degree of competence inthe area of fundamental solid state chemistry. In contrast,the U.S. and Japan appear to be more efficient in the technologytransfer between fundamental science and appliedengineering. Let us point out some research fields in whichwe can compare the competitiveness of Europe vs the U.S.and Japan. In bio-inspired inorganic materials synthesisincluding organic/inorganic hybrids, U.S. and Europe arevery active and Japan has a moderate activity. On the otherhand materials by rational design are relatively well-developedin Japanese industry and academic labs by comparisonwith U.S. which have a moderate and rather decreasingactivity. In Europe this type of activity is clearly moreimportant in academic labs than in industry. Combinatorialchemistry for materials discovery (parallel synthesis andscreening), is shrinking in U.S. whereas Japanese labsshow no or very limited interest for this approach. InEurope this activity is progressing especially in catalyticindustry.In all initiatives taken for developing inorganic materialsin different areas (ceramics, nanomaterials, etc.) synthesisand processing are at the heart of the programmes as shownfor example by the recent actions launched by U.S. as (i)NSF workshop report devoted to Fundamental ResearchNeeds in Ceramic (April 1999 - NSF Grant # DMR-9714807) (ii) National Nanotechnology initiative: leadingto the Next Industrial Revolution (Committee on Technology- National Science and Technology Council - February2000, Washington D.C.) (iii) Creation of a Centrefor Nanoscale Materials at Argonne National Laboratory.It is also noteworthy the big efforts made in Japan on thenanofabrication of materials and nanodevices.We note that computational methods can deal with anyimaginable chemical system, in principle, but the size andcomplexity of the systems is limited in the end by the availablecomputational resources and the quality of the algorithms.It is necessary to extend the global optimizationstage with simplified energy functions beyond simple ionicsystems to larger and more complex compounds. Similarly,on the ab initio level, full local optimizations for allelement combinations and comparatively large systemsmust become routine. Thus, improvements in the efficiencyand generality of the first three steps in the approachsketched above are of great importance over the nextdecade. But the major task for the future is the rationaldesign of synthesis routes, since predicted compoundshave to be synthesized in order to verify the calculationsand, of course, to make them accessible to applications.Designing and modelling synthetic routes is much moredifficult to achieve than structure prediction. Althoughsynthesis of solids via diffusion processes in close to idealsystems and e.g. chemical vapour deposition can be treatedquantitatively, predicting reaction paths on the energylandscape of multicomponent systems still seems to be farout of reach, not to mention steering such reactionsthrough control of external parameters. Thus, even in caseswhere a new compound and its structure have been predicted,one has to develop individual tailor-made synthesesguided by inspiration and experience.While being very fast, combinatorial chemistry has difficultieswhen dealing with a system where no compoundshave yet been synthesized, or when the individual synthesesare very sophisticated, as often happens in materialschemistry. Thus, in the future the design of combinatorialequivalents of traditional preparation methods will becrucial for a more general applicability of this method.MATERIALS SYNTHESIS AND PROCESSING2036.2.3. Future Visions and BreakthroughsAs pointed out above, there still exists a serious deficit inthe ability to produce (new) materials with desired intrinsicproperties and microstructures by rational design. Thissituation is particularly distressing, since significantprogress in science and technology has frequently beentriggered by novel materials with outstanding propertiesas well as by new processing methods. Thus, it is highlydesirable to improve efficiency and predictability of solidstate chemistry and materials research, not only withrespect to generating compounds with new compositionsand structures, but also with regard to tailoring their properties.This also holds true for the generation of specificmicrostructures and shapes, which in the end determinethe overall performance of a workpiece within a device.Furthermore, one should note, that for materials designthe fast automated screening of the reaction products is avery important component of the success of combinatorialchemistry. In order to avoid a bottleneck at this stage, itwill be crucial to develop new fast high-throughput screeningmethods (particular for properties of bulk materials).Finally, we observe that this approach has been restrictedto screening thermodynamic space with respect tocompositions only, but in the future a systematic parallelexploration of temperature and pressure variation shouldbe implemented.While there is an obvious element of competition betweenthe rational design described above and the high-throughputsynthesis, their particular strengths and weaknesseswill most likely result in a rather complementary range of

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART204applications. Thus, high-throughput will be at its best, ifthe goal of the optimization of chemical systems can beachieved by tuning compositions and other thermodynamicparameters, while the theoretical approach will be mostuseful in the exploration of the many « white spots » on thelandscape of chemistry.Interlocking of the various models that are of limited validityon their own will be central for the full theoreticaldescription of mesoscopic textures and microstructures,and the processes that produces them. Experimentally,chemical methods need to be developed that can achievemesoscopic structures perhaps via self-organized growthusing various kinds of templates.The synthesis and formation of individual nanostructureshave many promising opportunities, including dendriticpolymers, block copolymers, sol-gel chemistry and controlledcrystallization, aerosol nucleation, modified condensation,and nanotube growth. Research into selfassembly,net-shape forming, templating and other manufacturingapproaches will allow for a high level of controlover the basic building blocks of all materials. An importantchallenge is to scale up the laboratory processes anddevelop commercially viable production methods to manufacturestable nanostructures.6.2.4. Research Needs1. Synthesis of new materials with promising properties- Combinatorial chemistry: fast automated screening,new high-throughput syntheses, combinatorial explorationof full thermodynamic space- Reactions: controlled thermodynamic conditions, includingextreme pressures and temperatures, kineticcontrol in solid state reactions- Implementation of new synthetic strategies controllingchemical and structural homogeneities at themicroscopic scale level and below.2. Design of microstructure- Self-organized textures and microstructure- Hierarchically structured materials- Local control of size, shape and composition3. Computational methods- Global exploration of the configuration space of chemicalcompounds: applicability to all types of chemicalbonding, large and complex systems, rational planningof synthesis routes- Ab initio methods: design of transferable (pseudo-)potentials and basis sets for all elements, full localoptimization including cell and atomic coordinates- Modelling of microstructure: inter-locking of differenttime and spatial scales, combination of quantummechanical and classical simulations.6.3. Synthesis/Processing of Ceramics and Composite MaterialsT. Chartier | Ecole Nationale Supérieure de Céramique Industrielle, 87065 Limoges, France6.3.1. IntroductionCeramics are materials roughly defined as non-organic andnon-metallic solids, which provide a large range of propertiesand functions. Most forming methods of organic andmetallic parts are generally not suitable for ceramics, dueto the brittleness and to the refractarity of ceramic materials.Another essential difference between processing metalsand ceramics is that, in the first case, the separation ofthe industry that produces the material and the industrywhich fabricates the piece whereas, for ceramics, the samecompany fabricates the material and the piece.European laboratories have high competencies in materials(solid state chemistry for instance) but ceramists haveto produce pieces using these materials and basic researchin ceramic processing appears to be rather poor in Europe.Processing is critical because it generally controls the finalproperties of the part. With exception of glass, ceramicforming techniques are generally based on powder processingwith powder synthesis, forming and sintering. It isthen necessary to understand the fundamental mechanisms,which take place during the different steps of theprocess to obtain reliable and desirable properties of thefinal parts. Moreover, ceramic processing has also to considermethods that are not based on powder processing includingtechniques of deposition (chemical and physical)and crystal growth (single-crystal). Then processing researchincludes thin films and bulk pieces with the developmentof desirable microstructures and architectures.

6.3.2. State of the ArtIn the last 10 years, advances in ceramic processing haveenabled several technological breakthroughs.The development of new shaping techniques such as rapidprototyping or direct casting allows to design complexarchitectures adapted to desired improved and/or specificproperties. Rapid prototyping techniques (stereolithography,fused deposition, three-dimensional printing, directink-jet printing, selective laser sintering...) allow to fabricatenet-shape complex ceramic parts, directly from CADfiles. Direct casting exploits basic knowledge in colloidalchemistry by using interactions between particles in suspensionto transform a well dispersed suspension into acohesive green body.The better knowledge of densification mechanisms, thedevelopment of sintering models to predict the evolutionof microstructure during thermal treatment and the designof microstructure, for instance by using the nucleationand seeding (magnetic ferrite single crystal producedby recrystallization in the solid state, self-reinforced Si 3 N 4and SiC), lead to improved properties.The synthesis of specific powders and the better control ofchemical and of physical characteristics of ceramic powdersallow to obtain improved and/or reproducible propertiessuch as mechanical strength of structural ceramics(up to 1000 MPa for zirconia).In the field of ceramic processing, the efforts have to bedirected towards the following domains: 1) synthesis ofspecific powders, 2) shaping of ceramic components withdesirable microstructure and architecture, 3) sintering andmicrostructure development and 4) surface treatment.(a) Synthesis of specific powdersThe quality of the widely used commercial powders (alumina,zirconia, silicon carbide, silicon nitride, barium titanate)has slowly improved during this last decade. Thechemical and physical characteristics are now better controlledbut efforts have to be maintained. Then, betterproperties may be obtained due to more homogeneousmicrostructures and higher sintered densities. Consecutively,novel processing routes, based on colloidal science,which require constant surface properties, are under development.Moreover, the control of the surface chemistryduring the synthesis will lead to improved properties incomposite materials.As far as the particle size is concerned, nanosized particlesoffer the potential advantage to decrease the sintering temperatureand to lead to new properties. One future challengeis the processing of nanoparticles to produce bulkpieces. Nanoparticles should also be included in a matrix,ceramic or not, to fabricate nanocomposites with originalproperties. This requires the production of nanosized powders,at a commercial level.Future research needs1.Synthesis routes to produce specific powders, or homogeneousmixtures of powders, with well controlledchemical (surface) and physical properties (size, shapeand surface roughness),2. Synthesis routes to produce nanosized powders withwell-controlled characteristics.(b) Shaping of ceramic componentsThe recent efforts, in the domain of ceramic processing,are generally focused on the control of the microstructurebut the importance of the architecture is classically underestimatedand the conventional approach is limited to theimprovement of one specific property. Improved and/ororiginal properties require the design and the achievementof controlled architectures and microstructures. Then, thecontrol of the structure has to be performed over manylength scales, ranging from the particle size to the macroscopicdimension of the component. In this context, thecreation of new ceramics should be based on a new conceptof structure organization at different size-scales bycontrolling the morphology and the distribution of differentbuilding elements (particles, fibres, layers, interfaces,etc.) (Fig. 6.6).Two ways should be considered to direct the research inshaping of ceramics, first a better understanding of fundamentalmechanisms which take place in the different stagesof the forming, secondly the development of innovativetechniques, for instance, able to produce desirable architecturesor miniaturized components. An example concerningthe first point is a substantial improvement of thefundamental understanding in the colloid and interfacialscience that leads to low-cost techniques such as directcoagulation casting. But, there is a lack of models able topredict the behaviour of a concentrated suspension fromknowledge of interparticle forces, particle size distributionand particle shape. Rapid prototyping is an example of thesecond point. These techniques allow, for instance, to producefunctionally graded materials with complex shapesand very small parts with a good dimensional definition(electronic and mechanical components, microelectromechanicalsystems (MEMS)...). They are also promising forprocessing fine-scale piezoelectric ceramic/polymer compositesallowing for instance to improve the spatial resolutionof medical imaging transducers. Nevertheless, theseMATERIALS SYNTHESIS AND PROCESSING205

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART206new techniques remain under development and an industrialtransfer requires an improved knowledge of thedifferent systems used (mixture organic/ceramic) with abetter understanding of the role of ceramic/polymer interfacesin processing.The processing of nanosized powders constitutes one ofthe greatest challenges for the next years. This requires first,an improved understanding of colloidal behaviour at thenanoscale and secondly, the choice of suitable additives.A last point to consider is the development of more environmentalfriendly aqueous systems, even for water sensitivepowders (non-oxides, etc.).ArchitectureLaminar(macro-scale)MicrostructureGrainorientation(m-scale)Nanosizedparticledispersion(nm-scale)Organized structureFig. 6.6. Concept of organized structure (control of different properties).Future research needs1. The development of experimental and models to predictthe behaviour of a concentrated suspension from knowledgeof interparticle forces,2. The development of innovative shaping techniques toproduce desirable architectures and very small parts(mm length scale) with a good dimensional definition,3. The development of experimental and models to predictthe behaviour of nanoparticles concentrated suspensions,4. The development of aqueous formulations with specificpolymers systems.(c) Sintering and microstructure developmentDespite a good qualitative understanding of the microstructuredevelopment during sintering leading to a satisfactorycontrol of the sintered microstructure, the rigorousquantitative prediction of solid state sintering behavior isnot yet possible for ceramics that are generally complexmultiphase systems.The final objective of the use of nanoparticles is to maintaina nanosized microstructure after sintering in orderto obtain improved properties. The understanding of themicrostructure development is then critical in this case.Future research needs1.The development of models for quantitative predictionof microstructure evolution during sintering,2.The use of new methods of characterization for quantitativemicrostructure evolution,3.The achievement of the basic values of atom diffusivityand surface energy necessary for the model,4.The development of predictive models of microstructureevolution during sintering of nanoparticles.(d) Surface treatmentSurface treatment, including deposition of thin ceramicfilms and thick ceramic coatings, becomes more and moreimportant for electronic devices, thermal and tribologicalapplications. The processing methods for thin films andcoatings are specific and largely differ from usual powderprocessing. The deposition of quality thin films requires thefundamental understanding of nucleation and growth mechanismsof ceramics that influence the microstructure, thesurface morphology and stresses. This knowledge could leadto the deposition of microporous thin films which are promising,for instance for dielectric and optical applications.A future orientation should be likely the deposition ofceramic thin films on polymer substrates that imposes alow temperature process.Future research needs1.The fundamental understanding of nucleation andgrowth mechanisms,2.The development of low temperature deposition processes,3.The development of experimental and model of the evolutionof stresses during growth of thin films and thickcoatings.6.3.3. Competitiveness of Europe vs. U.S. and Japan inCeramic ProcessingA great part of the American research is focussed on theceramic processing science for instance for integration ofceramics with other materials (polymers, metals, drugs,etc.). The most important forces in Japan are carried outon new materials with new functions in a wide range ofadvanced fields (communication, energy, environment,life, etc.) and ceramic processing appears in a second plan.

At present, the U.S. is likely the main competitor ofEurope in the field of processing of ceramic materials, butwith research topics more driven by technological applicabilitythan by pure basic scientific curiosity. It is evidentthat there is a drastic need of fundamental research inceramic processing in Europe which is poor in comparisonto U.S.6.4. Synthesis of Polymeric MaterialsReferences1. Fundamental Research Needs in Ceramics, USA NSF Workshop Report,Y.M. Chiang and K. Jakus, April 1999.2. Joint Research Consortium of Synergy Ceramics, Fine Ceramics ResearchAssociation, Japan, 1999.MATERIALS SYNTHESIS AND PROCESSINGP. J. Lutz | Institut Charles Sadron, 67083 Strasbourg, France2076.4.1. Scope of Polymer SynthesisSynthetic polymers are utilized increasingly in our dailylife and manifold industrial applications have contributedto their expansion. Chemical industry devotes a great partof its activity to these polymeric materials. They are employedas substitutes for and /or in combination with metals,glass, ceramics, wood and paper. The worldwide evolutionover recent years of the consumption of polymericmaterials is given in Fig. 6.7 together with the repartitionof the different polymeric materials. The purpose of thepresent report is to discuss the approaches to design severalpolymeric materials over a large range of properties.The major part is concerned with a general discussion onthese polymerization processes with respect to the natureof the polymerization procedure and its implication onthe control of the molar mass and its distribution, the functionality,on the composition for copolymers and on thestructural parameters. Selected examples will be presentedand discussed more in detail: controlled free radicalpolymerization, coordination polymerization and the specialcase of free radical polymerization in emulsion includingthe recent developments on the polymerizationin nano-structured medium. Special attention will be givento the recent breakthroughs in theses polymerizationprocesses. The second part concerns some conclusionsand recommendations concerning the future orientations.North AmericaEuropeJapan738687%12% 1%4319801995 2000Standard Polymers [polyolefins (47%) and others (40%)]Engineering PolymersSpeciality PolymersFig. 6.7. Evolution of plastics consumption (kg/person) in North America, Europe and Japan [1] (a). Worldwide market for plastics in 1996 [1,2] (b).

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART2086.4.2. State of the Art of Polymer Synthesis Research 1(a) Controlled polymerization processesAnionic polymerization carried out under proper conditionswith efficient metal-organic initiators was considereduntil recently to be the most powerful way to design alarge scope of polymers of controlled molar mass, functionality,composition and/or topology. Anionic polymerizationhas several intrinsic limitations: It requires strictexperimental conditions and is only applicable to a limitednumber of monomers. Therefore the number of materialsobtained by anionic polymerization processes is rather restricted.The specific case of the synthesis via anionic stereospecificpolymerization of elastomeric materials basedon polydienes has to be mentioned. Therefore anionic polymerizationremains the method of choice to control thetopology of polymers. Two recent breakthroughs in the domainhave to be outlined. They concern the good controlof the anionic polymerization at high monomer concentrationsand the controlled anionic polymerization ofmeth(acrylic) monomers even at room temperature. Thesetwo results obtained in the frame of collaborations withEuropean industrial companies have opened new perspectivesfor the preparation of well-defined materials. On thecontrary, polymerization processes based on free radicalpolymerization are extensively used for the preparation ofa large scope of materials in industrial productions. Freeradical polymerization is easy to process, can be applied indilute solution, in suspension or emulsion and even in thebulk. Free radical polymerization is well know to be applicableto a much larger number of monomers. In most cases,that polymerization process leads to high molar massesand does not allow to the control of structural parameters.This is attributed to the short live time of growing sitesleading to irreversible termination reactions. Block copolymersynthesis is almost impossible. Many efforts havebeen devoted recently to obtain a better control of structuralparameters in free radical polymerization. New generationsof initiators have been introduced in U.S., Japan andalso in Europe. These systems called controlled radicalpolymerization [3] based on a reversible termination reactionor a reversible chain transfer reaction controlling theactivation deactivation cycles have been subject of increasinginterest in the last five years. An equilibrium takes placebetween the macromolecular radical and a dormant covalentcounter part. Pioneering work has been done byRizzardo [4] and later by Georges [5]. Two systems haveemerged: Nitroxide mediated polymerization and Atom1) A more detailed discussion on the different topics presented in thatreport is given in the following reference:Materials Science and Technology, A Comprehensive Treatment,Volume Synthesis of Polymers, Ed. A.D. Schlüter, Wiley-VCHWeinheim-New-York (1999)Transfer Radical Polymerization (ATRP). They were firstapplied to homogeneous polymerization processes. Theirextension to water represents a major challenge for manypolymer chemists. That point will be discussed in the sectionpolymerization processes in nano structured medium.Nitroxide such as those derived from TEMPO (2,2,6,6-tetramethylpiperidinyl) are used for the reversible trappingof growing radicals. At a temperature below 100°Cthe resulting alkoxyamine is stable whereas at higher temperaturethe C-O bond undergoes homolitic cleavage thusallowing again the propagation. These systems have beenshown to be efficient for controlled polymerization of styreneand substituted styrenes. They are less efficient foracrylic ester monomers. On the contrary phosphonylatednitroxides introduced by Tordo et al (France) in collaborationwith Elf-Atochem are well suited for the controlledfree radical polymerization of both classes of monomers.Similar work has been performed worldwide by severalother groups.For the ATRP polymerization, copper complexes or rutheniumsalts were developed by Matyjaszewski (U.S.) [6]and Sawamoto (Japan) [7] to polymerize vinylic monomersin a controlled way. ATRP is based on the reversible transferof halogen atoms between dormant alkyl halides andtransition metal catalysts by redox chemistry. High molarmass polymers and well-defined block-copolymers couldbe obtained. The major limitation to the extend the processto industrial applications is due to the presence in thematerial of inorganic salts or complex ligands.Reversible Addition Fragmentation Transfer (RAFT) polymerizationrepresents an alternative to the two controlledfree radical polymerization processes just described andoffers interesting perspectives.(b) Polymerization and copolymerization of olefins bycoordination catalystsPolymeric materials based on polyethylene (PE) and polypropylene(PP) and their related polymerization processeshave attracted increasing interest over the last 50 years.They more and more replace other polymers as they combinelow prices with tunable properties and good recyclingbehaviour. They can be designed for numerous applicationssuch as packaging, textile fibres, automotive partsand even as biomaterials after appropriate modification.The first decisive step was the discovery by Ziegler-Nattain the 50 th of the transition metal catalyzed polymerizationof olefins opening new perspectives in the domain of commodityand specialty polymers. Continuous progresseshave been made with the aim of improving their efficiency.In the last 20 years new generations of the heterogene-

ous Ziegler-Natta based catalysts have been introduced inEurope, Japan and in the US. Important cost reductionscould be obtained with the 3 rd and 4 th generation of Ziegler-Nattacatalysts based on titanium trichloride/magnesiumchloride in the presence two Lewis bases. These catalystsare highly stereospecific and very active.In the 80’s the introduction by Kaminsky [2](Germany) ofthe homogeneous catalysis based on metallocenes and activatedby methylaluminoxane was expected to revolution thedomain of organometallic chemistry, polymer synthesis andprocessing. The driving force for the use of these catalystsis the existence of single-site feature enabling the precisecontrol of molecular parameters: narrow molar mass distribution,chemical composition and microstructure [8,9].New tailor-made polymers could be obtained and someproducts based on metallocene catalysts are now on themarked including some types of isotactic polypropylenes.The discovery in industrial companies in Europe and laterin the U.S. of the late transition metal complexes less oxophiliccompounds and therefore less sensitive to polar media.These catalysts have generated considerable interestfor the polymerization and copolymerization of olefins withpolar and especially acrylic monomers [10,11]. In the1995s Brookhart and co-workers have developed a newgeneration of palladium and nickel (late transition metals)catalysts aimed either at the polymerization of olefins or atthe copolymerization of olefins with some acrylates. Theincorporation of functional groups into hydrocarbon polymersconstitutes an interesting approach for modifying thechemical and physical properties of these polymers, suchas permeability, compatibility, dyeability, adhesion, solidstate morphology, and rheology. The same generation ofcatalysts has been shown to provide access to poly(olefins)of controlled topology.(c) Polymerization in nanostructured media 2Free radical polymerization in colloidal dispersions suchas emulsions has been increasingly used over more than50 years to design in industrial processes numerous intermediatesfor paints adhesives polishes and coating materials.That polymerization process has been subject ofconstant interest and even, if some problems are still open,particles of controlled size and functionality are now easilyaccessible. In the 80s the concept of microemulsion polymerizationhas been introduced. That polymerization innano-structured media (micelles, microemulsions) basedon classical free radical polymerization represents a2) A detailed overview of the present situation in the domain ofpolymerization in dispersed medium is given in the followingreference : Macromol. Symp. 150, 2000.important progress in controlled synthesis of functionalpolymers carrying hydrophobic and or ionic sites. The specificfeatures of the processes – small size of the dropletsand large overall and large interfacial aria – result in aunique microenvironment which can be taken advantageof the product to produce novel materials with widely differentproperties designed for a large scope of applications[12]. The polymerization in aqueous emulsion or suspensionto design materials directly in water for various applicationssuch as painting/coating. Increasing interest hasbeen devoted to such (co-polymerization) reactions inwater who constitutes an ideal medium for at least two reasons:environment and safety. Presently such argumentsare very important in most countries. Beside the classicalfree radical polymerization, it has been shown that ATRPis also applicable in emulsion. In addition it has to be mentionedthat amphiphilic block copolymers were designedby ATRP or nitroxide mediated polymerization as stabilizersin the free radical polymerization emulsion of styrene.These reactions are yet limited to polymers where no tacticitycontrol is required. Only recently work has been doneto develop efficient catalytic systems for the polymerizationof olefins in water. Pioneer work on coordination polymerizationin water has been done in the group of Lyon incollaboration with Elf Atochem. Emulsion polymerizationof ethylene polymerization using bimolecular P,O-chelatedligands based on nickel yielded in aqueous dispersedmedium latexes of HDPE. Similar work has been done inGermany to prepare with palladium catalysts branchedpoly(ethylenes).6.4.3. Future Visions and Expected BreakthroughsIn the present report the most important polymerizationprocesses have been presented and their contribution tothe preparation of materials covering a large range of propertiesdiscussed.The preparation of well-defined linear homo or block copolymersincluding functional polymers via controlled freeradical polymerization is now well possible for an extendednumber of monomers and therefore provides access to variousmaterials. The stereospecific controlled free radicalpolymerization remains a major challenge and work shouldbe done along that line. The combination of controlled freeradical polymerization procedures with a polymerization inemulsion (or in nano-structured medium) has been shownto access materials of controlled structural parametersdirectly in water. That domain should be examinedthoroughly in the near future.MATERIALS SYNTHESIS AND PROCESSING209

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART210The possibility to design polyolefins with controlledbranching or containing controlled amounts of polarmonomers by low pressure polymerization processes representsalso attractive perspectives for the low cost industrialpreparation of materials. The search for new familiesof non metallocene catalysts with enlarged possibilitiesshould be supported.The possibility to polymerize olefins in water has beendemonstrated. Further work in that direction should bestrongly supported in Europe. The heterogeneization ofmetallocenes catalysts represents also an important challenge.Many other possibilities or polymerization conditions /reactionsexist or are under investigation for the preparationof polymeric materials. Among these, the chemistry in themolten state has to be mentioned, this concerns the chemicalmodification of polymers and their synthesis startingfrom monomers. Along the same line the polymerizationin supercritical carbon dioxide constitutes a great deal.The increasing contribution of various polymerizationprocesses to the synthesis of polymeric biomaterials ofcontrolled characteristics has to be highlighted.1.2.3.4.5.6.7.8.9.10.11.12.ReferencesP. Barghoorn; U. Stebani; M. Balsam, Acta Polymer, 49 (1998) 266.W. Kaminsky, J. Chem. Soc., Dalton Trans., 1413 (1998)K. Matyjaszewski; “Controlled Radical Polymerization”, ACS Symp. Ser.Washington, D.C, 685, (1998).E. Rizzardo, Chem. Aust. 54 (1987) 32.M.K. Georges, R.P.N. Veregin, P.M. Kazmaier, G.K. Hamer, Macromolecules26 (1993) 2987.J. Qiu, K.Matyjaszewski, Acta Polym. 48 (1997) 169.M. Sawamoto, M. Kamigaito, Trips 4 (1996) 371.K. Soga, T. Shiono, Prog. Polym. Sci., 22 (1997) 1503.A.E. Hamielec, J.B.P. Soares, Prog. Polym. Sci., 21 (1996) 651.G.J.P. Britovsek, V.C. Gibson, D.F. Wass, Angew. Chem. Int. Ed, 38, (1999428.S.D.Ittel, L.K. Johnson, M. Brookhart, Chem. Rev., 100 (2000) 1169.F. Candau, Polymerization in Microemulsions, Handbook of MicroemulsionScience and Technology, Marcel Dekker Inc, New-York (1999).6.5. Metal-Matrix Composites: Challenges and OpportunitiesA. Mortensen | Swiss Federal Institute of Technology, 1015 Lausanne, SwitzerlandT.W. Clyne | University of Cambridge CB2 3QZ, United Kingdom6.5.1. Scope and DefinitionsA metal matrix composite (MMC) combines into a singlematerial a metallic base with a reinforcing constituent,which is usually non-metallic and is commonly a ceramic.By definition, MMCs are produced by means of processesother than conventional metal alloying. Like their polymermatrix counterparts, these composites are often producedby combining two pre-existing constituents (e.g.a metal and a ceramic fibre). Processes commonly usedinclude powder metallurgy, diffusion bonding, liquid phasesintering, squeeze-infiltration and stir-casting. Alternatively,the typically high reactivity of metals at processingtemperatures can be exploited to form the reinforcementand/or the matrix in situ, i.e. by chemical reaction within aprecursor of the composite.There are several reasons why MMCs have generated considerableinterest within the materials community for nearly30 years:1. The “composite” approach to metallurgical processingis the only pathway for the production of entire classesof metallic materials. Only in this way can aluminium,copper, or magnesium be combined with significantvolume fractions of carbide, oxide or nitride phasesbecause, unlike iron, the solubility of carbon, nitrogenor oxygen in the molten metal is (with the exception ofO in Cu) far too low.2. The approach facilitates significant alterations in thephysical properties of metallic materials. Compositesoffer scope for exceeding the specific elastic modulusvalue of about 26 J kg -1 , which is exhibited by all the mainengineering metals. Composites also offer the only pathwayfor producing materials with tailored physical propertycombinations: an example is that of low thermalexpansivity combined with high thermal conductivity,a combination of importance for electronic packaging.

3. MMCs offer significant improvements over their polymermatrix counterparts with regard to several properties,including tolerance of high temperature, transversestrength, chemical inertness, hardness and wearresistance, while significantly outperforming ceramicmatrix composites in terms of toughness and ductility.4. Exceptional properties can be obtained in some cases.An example is that of 3M’s Nextel-reinforced aluminiumcomposites, which exhibit along the fibre directiona tensile strength of 1.5 GPa, a compressive strength of3 GPa and a transverse strength above 200 MPa, in amaterial of density only slightly above 3 g cm -3 .Short Fibre- and Whisker-Reinforced metals. These containreinforcements with an aspect ratio of greater than 5, butare not continuous. These composites are commonly producedby squeeze infiltration. They often form part of alocally reinforced component, generally produced to netor near-net shape. Their use in automotive engines is nowwell established.Continuous Fibre-Reinforced Metals contain continuousfibres (of alumina, SiC, carbon, etc.) with a diameterbelow about 20 µm. The fibres can either be parallel, orpre-woven before production of the composite; this is generallyachieved by squeeze infiltration.Monofilament-Reinforced metals contain fibres that are relativelylarge in diameter (typically around 100 µm), availableas individual elements. Due to their thickness, thebending flexibility of monofilaments is low, which limitsthe range of shapes that can be produced. Monofilamentreinforcedmetals can be produced by solid state processesrequiring diffusion bonding: they are commonly basedon titanium alloy matrices, which are well-suited to suchtechniques.MATERIALS SYNTHESIS AND PROCESSING211Interpenetrating phase composites are ones in which themetal is reinforced with a three-dimensionally percolatingphase, for example ceramic foam.Fig. 6.8. Duplex particle size distribution in a commercially available70vol% (PRIMEX) SiC particle reinforced aluminium MMC for electronicsubstrate application.Liquid phase sintered metallic materials, include the cementedcarbides, in which carbide particles are bondedtogether by a metal such as cobalt, and the tungsten heavyalloys.MMCs come in several distinct classes, generally definedwith reference to the shape of their reinforcement:Particle-Reinforced metals (PRMs) contain approximatelyequiaxed reinforcements, with an aspect less than about 5.These are generally ceramic (SiC, Al 2 O 3 , etc.). PRMscommonly contain below 25vol.% ceramic reinforcementwhen used for structural applications, but can have asmuch as 80vol% ceramic when used for electronic packaging(Fig. 6.8). In general, PRMs are at least approximatelyisotropic. They are produced using both solid state (powdermetallurgy) and liquid metal techniques (stir casting,infiltration). Their mechanical properties, while often inferiorto those of fibre-reinforced metals, are more or lessisotropic and often represent, at moderate cost, significantimprovements over those of corresponding unreinforcedmetals.6.5.2. State of the ArtMMCs have been extensively studied. SiC monofilamentreinforcedtitanium has been the subject of many investigations,as have aluminium alloys containing up to 25vol% SiC and Al 2 O 3 particles. These materials have beenproduced by industry (including Alcan, Textron, Alcoa,AMC, BP, and 3M) in relatively large quantities, such thatthey have been made available for testing at researchlaboratories and universities. Their novelty, and their interestingmechanical behaviour (at both micro- and macroscopiclevels), have led to many publications, exploringmany features of their microstructure, deformation, andfracture behaviour. Many mechanisms responsible fortheir mechanical characteristics are now well understood,including the roles of damage development, internal stresses,reinforcement clustering, interfacial bond strength andthe effects of the presence of the reinforcement on agingof the matrix. However, much work remains to be donebefore required property combinations can be systematicallyachieved via microstructural design.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART212The processing of MMCs has also generated much interest.Many publications have appeared over the pastdecades on this subject. Commonly, such studies have presentednovel composite materials or processes, withoutadvancing the underlying science concerning the transportphenomena involved or their relationship with microstructuralfeatures of the product. For example the rate ofsolid state consolidation of a mixture of two different powdersis not yet predictable, nor is the rate of liquid phasesintering of metal bonded carbides.With regard to industrial applications, MMCs now have aproven track record as successful “high-tech” materials ina range of applications, bringing significant benefits (interms of energy savings, or component lifetime) and havingdocumented engineering viability. These often relateto niche applications, where achievable property combinations(e.g. high specific stiffness and weldability; highthermal conductivity and low thermal expansion, or highwear resistance and low weight and high thermal conductivity)are attractive for the component concerned. Manysuch niches, ranging from diesel engine pistons to automotiveengine cylinder liners, are of considerable industrialsignificance. Barriers to their wider exploitation includeprice (which is, of course, inter-related with global andspecific usage levels), shortage of property data and designguidelines and (perceived) limitations to their ductility andtoughness.6.5.3. Challenges and Opportunities: Priorities in EuropeanResearchSeveral challenges must be overcome in order to enhancethe engineering usage of MMCs. Research efforts requiredto overcome these challenges span the spectrum frombasic, fundamentals-oriented research, to more appliedengineering projects.1. There is a need to advance our understanding of processingfundamentals, particularly concerning establishedprocesses such as squeeze infiltration, liquidphase sintering, and powder metallurgy. Progress in thisarea is required, both to drive innovation and to enablequantitative process simulation, optimization, andcontrol. In particular, progress in this area is critical forcontrolling internal defects – an important goal withthese materials, given that they are more brittle thanunreinforced metals.2. Property improvements must be sought, particularly inductility and toughness. Systematic investigations arerequired of the fundamental links between microstructureand properties. Much work to date has focused ononly a few commercial or near-commercial materials,which have been characterized in detail, but do not providefull insight into basic microstructure-property relations,such as the link between particle size or spatialdistribution and mechanical properties.3. There is clearly scope for improvements in the propertiesof reinforcements. Substantial advances in fibresfor MMCs have been achieved at the 3M company: interms of strength, for example, the performance of aluminafibre-reinforced aluminium has doubled over thepast decade. Recent work has also shown that significantdifferences exist between ceramic particles thatcan be used as reinforcements for aluminium (Fig. 6.9).Research on the economical production of highstrength, low-cost, ceramics for the reinforcement ofmetals would be very timely.Fig. 6.9. Optical micrograph of a pressure-infiltrated composite combiningpure aluminium with high-performance alumina particles: thismaterial, despite its high ceramic content, displays a tensile elongationof 4.5% and a toughness on the order of 25 MPa√m.4. An important issue concerns secondary processing.Operations such as welding and machining, and alsothe definition of recycling strategies, are challengingwhen applied to MMCs. Research in this area is criticalfor certain applications and for the life-cycle engineeringof these materials.5. Much work to date has focused on aluminium matrixcomposites, but copper, magnesium, and iron-basedmatrix composites do offer promise in specific applications.These include electronic applications for copper-

matrix composites, and chemical processing environmentsfor steel matrix composites. These systems deserveexploration, again with emphasis on fundamentals,rather than the development of this or that specificcomposite.These windows of opportunity in research are ones which,in large part, call for partnerships between different laboratoriesand researchers. For instance, a capability forcontrolled processing of these materials is needed for thegeneration of samples and microstructures that can beused in the exploration of microstructure-property relations.Unlike unreinforced alloys, in which the microstructurecan be varied using conventional and well-establisheddeformation and heat-treatment processes, the processingof MMCs requires specialized equipment and know-how.The establishment of a European centre of excellence inMMC research, able to cover the entire spectrum fromprocessing to performance, and providing a hub for such acoordinated effort, would be highly opportune.References1. T.W. Clyne, and P.J. Withers, An Introduction to Metal Matrix Composites.Cambridge University Press, Cambridge, 1993.2. Fundamentals of Metal Matrix Composites, S. Suresh, A. Mortensenand A. Needleman Eds., Butterworths, Boston, 1993.3. Comprehensive Composite Materials, Volume 3: Metal Matrix Composites,Volume editor: T.W. Clyne, Series editors: A.Kelly and C. Zweben,Pergamon, Oxford UK, 2000.4. Brite Euram project: Assessment of Metal Matrix Composites for Innovations:http://mmc-assess.tuwien.ac.at/MATERIALS SYNTHESIS AND PROCESSING2136.6. Ceramic Matrix CompositesR. Naslain | Université Bordeaux 1, 33600 Pessac, France6.6.1. IntroductionCeramic matrix composites (CMCs) have been developedto overcome the intrinsic brittleness and lack of reliabilityof monolithic ceramics, with a view to introduce ceramicsin structural parts used in severe environments, such asrocket and jet engines, gas turbines for power plants, heatshields for space vehicles, fusion reactor first wall, aircraftbrakes, heat treatment furnaces, etc. It is generally admittedthat the use of CMCs in advanced engines will allowan increase of the temperature at which the engine can beoperated and eventually the elimination of the coolingfluids, both resulting in an increase of yield. Further, theuse of light CMCs in place of heavy superalloys is expectedto yield significant weight saving. Although CMCs arepromising thermostructural materials, their applicationsare still limited by the lack of suitable reinforcements, processingdifficulties, sound material data bases, lifetimeand cost.6.6.2. Ceramic Matrix Composite SpectrumA given ceramic matrix can be reinforced with either discontinuousreinforcements, such as particles, whiskers orchopped fibres, or with continuous fibres. In the first case,the enhancement of the mechanical properties, in termsof failure strength and toughness, is relatively limited butit can be significant enough for specific applications, a wellknown example being the use of ceramics reinforced withshort fibres in the field of the cutting tools (SiC w /Si 3 N 4composites). Among the discontinuous reinforcements,whiskers are by far the most attractive in terms of mechanicalproperties. Unfortunately, their use raises importanthealth problems both during processing and in service.Conversely, continuous reinforcements, such as fibreyarns, are much more efficient, from a mechanical standpoint,but they are more expensive and more difficult touse in a ceramic matrix in terms of material design and processing.There is a wide spectrum of CMCs depending on thechemical composition of the matrix and reinforcement.Non-oxide CMCs are by far those which have been themost studied. Such a choice could appear surprising sincethe atmosphere in service is often oxidizing. That choicecould be explained as follows. The most performant fibres,in terms of stiffness, failure strength, refractoriness anddensity are non-oxide fibres, i.e. carbon and silicon carbidefibres. Further, carbon fibres are extensively used involume production of polymer-matrix composites. As a result,they are much cheaper than all the other fibres (glassfibres excepted). Second, in order to avoid compatibility

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART214problems, which are crucial at high temperatures, non-oxidefibres are preferably embedded in non-oxide matrices.Hence, the first non-oxide CMCs have been carbon/carbon(C/C) composites. They have been initially designedand produced for use in rocket engines and re-entry heatshields, i.e. under extremely severe service conditions butshort lifetimes. In a second step, C/SiC and SiC/SiC compositeswere developed in order to increase the oxidationresistance of the materials and hence their lifetimes inoxidizing atmospheres. Silicon nitride was also used asmatrix although it is less stable at high temperatures thansilicon carbide.Oxide-CMCs would obviously be the best choice, from athermodynamic standpoint, for long term applications inoxidizing atmospheres. Unfortunately, oxide fibres, althoughthey are refractory, tend to undergo grain growthat high temperatures, (which results in a fibre strengthdegradation) and exhibit a poor creep resistance. Further,they display much higher densities than say carbon fibres(4 g/cm 3 for alumina versus 2 for carbon). Attempts havebeen made to improve the high temperature properties ofoxide fibres with limited success. Despite these disadvantages,Al 2 O 3 /Al 2 O 3 and derived CMCs have been, andare still, extensively studied.6.6.3. State of the Art in CMC ProcessingCMCs can be produced according to either gas phaseroutes or liquid phase routes, each of them having advantagesand drawbacks.In gas phase routes, i.e. the so-called chemical vapor infiltration(CVI) processes, the reinforcements (usually as amultidirectional preform) is densified by the matrix depositedfrom a gaseous precursor, e.g. an hydrocarbon forcarbon or a mixture of methyltrichlorosilane and hydrogenfor silicon carbide. It is now well established that a fibrecoating, referred to as the interphase, has to be depositedon the fibre prior to the infiltration of the matrix in order tocontrol the fibre-matrix (FM) bonding and the mechanicalbehavior of the composite. Pyrocarbon (PyC), boronnitride or (PyC-SiC)n and (BN-PyC)n multilayers, withan overall thickness ranging from about 0.1 µm to about1 µm, displaying a layered crystal structure (PyC, BN) or alayered microstructure (multilayers), are the most commoninterphase materials in non-oxide CMCs. The mainrole of the interphase is to deflect the microcracks whichform in the matrix under loading and hence to protect thefibre form notch effect (mechanical fuse function).There are several versions of the CVI-process. The mostcommonly studied and used version is isothermal/isobaricCVI (or I-CVI). It is a relatively slow process since masstransfer in the preform is mainly by diffusion and it yieldssome residual porosity and density gradient. Conversely,I-CVI is a clean and flexible process (it can be used to densifysimultaneously a large number of preforms, eventuallyof different shapes). For these reasons, it is the preferredprocess at the plant level. It is well suited to the fabricationof relatively thin parts.In order to increase the densification rate and hence toreduce the processing times, temperature or/and pressuregradients can be applied to the preform. In temperaturegradient CVI (TG-CVI), or forced CVI (F-CVI), theprocessing time can be reduced by one order of magnitudewith respect to I-CVI. A similar processing time loweringhas also been reported for the film-boiling (or calefaction)process, in which the heated fibre preform is directlyimmersed in a liquid matrix precursor.Finally, pressure pulsed-CVI (P-CVI) has been recentlypresented as a way to engineer, at the micrometre (or evennanometre) scale, either the interphase or the matrix.Based on this technique, multilayered self-healing interphasesand matrices (combining crack arrester layers andglass former layers) have been designed and produced,through a proper selection of chemical composition of thelayers. An example of such highly tailored composites isshown in Fig. 6.10.Fig. 6.10. Example of multilayered self-healing matrix ceramic matrixcomposite produced by P-CVI. The matrix comprises crack arresterlayers and glass-forming layers.

In the liquid phase routes, the fibres first coated with aninterphase (e.g. by I-CVI) are embedded in a liquid precursorof the matrix. In the reactive melt infiltration (RMI)processes, a fibre preform is impregnated by capillary forceswith a liquid which reacts either with a solid phase usedto consolidate the fibre preform (SiC-Si matrices formedthrough liquid silicon infiltration of a carbon-consolidatedpreform) or with the atmosphere (Al 2 O 3 -Al matricesformed through liquid aluminium infiltration and chemicalreaction with an oxidizing atmosphere). Among otheradvantages, the RMI-processes are fast and can be appliedto thick preforms. They also yield materials of low residualporosities and high thermal conductivities.In the polymer impregnation and pyrolysis (PIP) processes,the fibres are embedded in a polymeric precursor of thematrix, such as a thermosetting resin or a pitch for carbonor a polycarbosilane for SiC, and the green composite isthen pyrolyzed. Such processes are relatively flexible sincethe composition of the precursor can be tailored. Conversely,a shrinking of the matrix occurs during the pyrolysisstep owing to the evolution of gaseous species. As aresult, several PIP-sequences have to be applied in orderto achieve a low enough residual porosity, which is timeand labour consuming. Shrinkage can be limited by loadingthe liquid precursor with suitable fine powder, i.e. byusing a slurry. Finally, the residual porosity can also significantlybe reduced through a hot pressing step, an alternativethat supposes that the matrix displays enough plasticitynot to damage the fibres. This liquid impregnation/hotpressing technique is well suited to the fabrication of glassceramicmatrix composites.6.6.4. Expected Breakthroughs and Future VisionsThe future of CMCs is directly depending on progress thatwould be achieved in the availability of higher performanceconstituents (fibres, interphases and tailored matrices) aswell as in processing cost reduction.As far as the reinforcements are concerned, two main breakthroughsare expected : (i) the availability of a low cost nonoxidefibre that could be used up to about 1500°C and (ii)the development of a refractory oxide fibre resistant tograin growth and creep. Oxygen-free quasi-stoichiometricSiC fibres display much better high temperature propertiesthan their Si-C-O counterparts fabricated from polycarbosilaneaccording to the Yajima’s route. However, theyare too costly (with respect to carbon fibres and CMC volumeproduction) and their failure strain is too low. AmorphousSi-B-C-N fibres, presented as creep resistant at hightemperature, are still at a development stage. Althoughalumina-based binary oxide fibres, e.g. mullite/alumina oralumina/YAG fibres, represent a significant progress interms of creep resistance with respect to pure -aluminafibres, further improvement is still necessary to match thehigh temperature properties of non-oxide fibres. Finally,nanotubes, with their outstanding mechanical properties,may raise problems similar to those previously encounteredwith whiskers.The spectrum of suitable interphase materials that couldbe used in a realistic manner in CMCs remains extremelynarrow. In non-oxide CMCs, there is presently no alternativeto the carbon-based interphases. Boron nitride is obviouslythe only potential candidate. However, its sensitivityto moisture when poorly crystallized and its low bondingto SiC-based fibres are subjects of concern. Solving thesetwo problems will be an interesting breakthrough. Thesearch for new interphase materials, displaying a betteroxidation resistance than carbon and boron nitride andwhich could be easily deposited in situ in multidirecitonalfibre preforms, should be strongly encouraged.The recent discovery of the self-healing multilayered matrices(Fig. 6.10) has been an important breakthrough sinceit permits the use of non-oxide CMCs in oxidizing atmospheres.The concept should obviously be further developedin terms of material selection.Finally, the processing cost of CMCs should be reduced(although the main contribution to the total cost of a givenpart is presently, e.g. in a SiC/SiC composite, that of thereinforcement, as previously mentioned). Gas phase routeprocesses with a significant reduction of the overall densificationtime, liquid phase route processes with a limitednumber of PIP-sequences (through the use of appropriateprecursors), both being compatible with CMC volumeproduction, would obviously be significant breakthroughs.6.6.5. Future Directions of ResearchThe interest of CMCs as thermostructural ceramics is nowwell established but their volume production at the plantlevel is still a challenge, which requires an important effortof research at the level of the European Union. Possibledirections of research are :• Development of low cost ceramic fibres (both non-oxideand oxide fibers) that could be used up to about 1500°C(the EU has presently no long term action that could becompared to what is done in Japan and U.S.).MATERIALS SYNTHESIS AND PROCESSING215

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART216• Development of one or two CMC(s), e.g. a SiC-basedand an alumina-based composites, including that of aninterphase material and a low cost processing technique,guided by one or two potential application(s).• Development of sound data bases on CMCs and theirconstituents (including that of suitable standard testsand modelling).6.7. Polymeric Composite MaterialsM. Giordano, S. Iannace and L. Nicolais | Universitá Federico II, 80125 Napoli, Italy• Development of the durability of CMCs, including thatof suitable internal and external oxidation protection(for non-oxide CMCs), lifetime prediction, residualmechanical and thermal properties characterization andmodelling.6.7.1. IntroductionPrincipal advantage of composite materials resides in thepossibility of combining physical properties of the constituentsto obtain new structural or functional properties.Composite materials appeared very early in human technology,the “structural” properties of straw were combinedwith a clay matrix to produce the first construction materialand, more recently, steel reinforcement opened the wayto the ferroconcrete that is the last century dominant materialin civil engineering. As a matter of fact, the moderndevelopment of polymeric materials and high modulusfibres (carbon, aramidic) introduced a new generation ofcomposites. The most relevant benefit has been the possibilityof energetically convenient manufacturing associatedwith the low weight features. Due to the possibilityof designing properties, composite materials have beenwidely used, in the recent past, when stiffness/weight,strength/weight, ability to tailor structural performancesand thermal expansion, corrosion resistance and fatigueresistance are required. Polymeric composites were mainlydeveloped for aerospace applications where the reductionof the weight was the principal objective, irrespectiveof the cost. The scientific efforts in this field were thereforefocused to the comprehension and optimization of thestructural performances of these materials. Structuralcomposite materials have been also used in other fieldssuch as automotive, naval transportation and civil engineeringbut the high cost still limits their applications. Acontinuous task has been making composite componentseconomically attractive. The effort to produce economicattractive composite components has resulted in severalinnovative manufacturing techniques currently being usedin the composite industry.6.7.2. State of the ArtNowadays, technology is devoted to the development ofnew materials able to satisfy specific requirements in termsof both structural and functional performances. The needof exploring new markets in the field of polymeric compositeshas recently driven the research in Europe towardsthe development of new products and technologies. In particular,activities on thermoplastic based composites andon composites based on natural occurring materials (environmentallyfriendly, biodegradable systems) have been ofrelevant interest in many European countries.Since the beginning of the 90’s years, U.S. and Japan haverecognized the need of expanding composite applications.In the field of materials, Japan put more emphasis thanU.S. on thermoplastic and high temperature resins. Moreover,due to the large extent of the textile industry in Japan,textile preforming is significantly more advanced thanin U.S, and this could lead to the development of cost-efficientautomated computer-controlled looms for complextextile shapes. In contrast to the U.S. approach of developingcomputational models to better understand manufacturingprocesses, Japanese manufacturing science appearsto reside in experienced workers who develop understandingof the process over long period of time. However,Japanese process and product development methods arebased on concurrent engineering methodology, which isbased on the integration of product and process design.Biomedical is another important field where compositesare applied. Materials, able to simulate the complex structuralproperties of the natural tissues, which are compositein nature, have been developed but there are still few

applications. This is due to the delay in the technologytransfer from different areas (composite industry and biomedical)and to the lack of cross-disciplinary strategies.In this field, U.S. maintain a leadership role but majorcentres exist in EU and Japan. Japan recognized the necessityof establishing a “National Institute for AdvancedInterdisciplinary Research” which is devoted to researchon subjects combining elements from various fields thatcannot be adequately treated within the bounds of traditionaldivisions of science. Among other topics, soft andhard tissue engineering are considered of relevant interests.Tissue engineering activities are growing, as well andstrong R&D programmes are present in EU and Japan,even though U.S. have a leadership role in the field.6.7.3. TrendsThe main trends in the structural composite field arerelated to the reduction of the cost which cannot only berelated to the improvement in the manufacturing technology,but needs an integration between design, material,process, tooling, quality assurance, manufacturing. Moreover,the high-tech industry, such as telecommunication,where specific functional properties are the principalrequirements, will take advantages by the compositeapproach in the next future. The control of the filler size,shape and surface chemical nature has a fundamental rolein the development of materials that can be utilized to developdevices, sensors and actuators based on the tailoringof functional properties such as optical, chemical and physical,magneto-elastic etc. Finally, a future technologicalchallenge will be the development of a new class of smartcomposite materials whose elasto-dynamic response canbe adapted in real time in order to significantly enhancethe performance of structural and mechanical systemsunder a diverse range of operating conditions.Over the long period term, U.S. and Japan believe thatadvances in the materials area would prompt new breakthroughsin the area of composites. In fact, the currentemphasis is on “fourth-generation” materials, i.e. thosethat are designed by controlling the behaviour of atomsand electrons, and which provide carefully tailoredfunctional gradients.6.7.4. Expectation and Needs for the Next 10 YearsThe composite materials market is expected to expand inareas where costs are today a strong limitation. The improvementof the mature manufacturing technologies willbenefit from integrated approach where product and processrequirements are set at design level. The expected reductionof manufacturing costs of the structural compositeswill expand applications of such materials to largescalemarkets such as civil and goods. Among theparamount needs are large-scale sponsored demonstrationproject; large scale and long-duration tests programmes;development and support of product certification andspecification protocols. In particular, it is demanding toexpand basic and applied research in the fields of materialssystems for homes, more durable materials to replaceaging pipelines and transmission systems, enhanced safetysystems for lighter automobiles made from composites,as well as research into even more rapid manufacturingprocesses, improvements in material handling and storage,and better, more durable and ever more benign resins.Significant breakthroughs are expected in new compositematerials especially in those applications, such as electronic,optic and biomedical, where functionality is themost relevant technical need. Relevant development willbe expected in the area of nanophase material synthesisand nanocomposite manufacturing technology. However,further optimization studies are required to implementlarge-scale production.Advanced SensorsApplication DrivenControl System Modelling New MaterialsImprove MatureTechnologiesManufacturing• Low Cost• Environmentally friendlyInnovative TechnologiesFig. 6.11. Main trends and expected breakthroughs (yellow) in themanufacturing of composite materials.Particular emphasis should be devoted to the R&D of compositematerials able to respond to dynamic variation ofthe operative conditions. Smart materials will provide thenervous systems, the brains and the muscles for the existingadvanced materials and structure that, at the moment,are a mere skeleton compared with the anatomy forecastedin a near future. Applications are expected in fields ofsensors, actuators, and biomedical.MATERIALS SYNTHESIS AND PROCESSING217

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART218NanophasesAdvancedTextilesAdvanced MatricesMaterialsEco-SustainableMaterialsMultifunctional StructuresSmart MaterialsActive MaterialsFig. 6.12. Main trends and expected breakthroughs (yellow) incomposite materials.BiomimeticThe quality of human life would be greatly improved bythe availability of artificial prostheses (bone, muscles, cartilage,and soft tissues) and organs able to restore, repairor replace structural and functional performances of thenatural tissues. The composite structure of the naturalsystems with its intrinsic complexity needs to be reproduced.Tissue Engineering is one of the major focuses ofbiotechnological research today, with the expectation thatthis type of biohybrid technology will ultimately transformthe practice of restorative clinics. The approach combinesthe principles of biology, material science and engineeringto culture cells, also heterogeneous groups ofcells, using polymeric biodegradable scaffolds as deliveryvehicles for cell transplantation to obtain complex threedimensionalcellular constructs. Composite materialsshould be properly designed to provide anisotropic and/or active scaffolds able to control the cell growth in thereconstruction of complex natural structures.The expected development of the aforementioned fieldsneeds a serious interdisciplinary approach. As already recognizedby U.S. and Japan, significant advancement inthe next 10 years in the field of a) functional and structuralcomposites through nanotechnologies, b) smart materialsand c) composite for biomedical applications requirescross-disciplinary strategies that should be addressed bycombining various scientific disciplines. The availablehuge amount of human and economic resources, spreadall over Europe, should be better coordinated by the creationof new interdisciplinary European research centresthat could face the world scientific and technological challengein these strategic fields.6.7.5. ConclusionsResearch activities, aimed to expand the applications incomposite industry, must be addressed to improve manufacturingcomposite technology, through a better integrationof product and process design; to develop newconstituent materials with better performances and/or forthe tailoring of structural and functional properties forspecial applications and for the development of new processesand new manufacturing technologies.Expected breakthroughs are related to the developmentof multi-component materials with anisotropic and nonlinearproperties, able to impart unique structural andfunctional properties. Applications include smart systems,able to recognize and to adapt to external stimuli, as wellas anisotropic and active composite systems to be usedas scaffold for tissue engineering and other biomedicalapplications.1.2.3.4.5.6.7.8.9.ReferencesCommunity Research & Development Information Service:www.cordis.luNational Science Foundation (USA): www.eng.nsf.gov/dmmiD.J. Wilkins, M.Ashizawa, J.B. De Vault, D.R. Gill, V.M. Karbhari,J.S.McDermott, JTEC PanelReport on “Advanced Manufacturing Technologyfor Polymer Composite Structure in Japan, (1994),http://itri.loyola.edu/polymers/toc.htmAdvanced Technology Programs, NIST, 1999 Funded Projects,www.atp.nist.govWTEC Workshop on R&D Status and Trends in Nanoparticles, NanostructuredMaterials, and Nanodevices, R.W. Siegel, E. Hu, M.C. Roco(eds.), 1998.http://www.ostp.gov/NSTC/html/iwgn/IWGN.Worldwide.Study/toc.htmWTEC Workshop on Tissue Engineering Research, Gaithersburg 2000.Japanese Ministry of International Trade and Industry:http://www.jwindow.net/GOV/CABINET/MITI/home.htmlProceedings of the 21st International SAMPE Europe Conference “InnovativeProcess and Material Solutions for Creative Design Effectiveness”,Paris, April 2000.T. Goldberg, SAMPE Journal, p.24, Vol.36, No.6, 2000.

6.8. Electronic SystemsP.S. Peercy | University of Wisconsin, Madison 53706-1691, United States6.8.1. IntroductionElectronic, photonic, and magnetic materials and systemsare at the heart of today’s technology revolution and areextremely fertile fields of research. Despite major advancesin our understanding and applications in these systems,many basic scientific questions remain unanswered, andwe continue to experience remarkable breakthroughs on aregular basis. With increased scientific understanding, wehave been able to exploit electronic, photonic, and magneticmaterials and systems for amazing technological advances.These technological advances lead in turn to powerfulresearch tools that enable us to advance our scientificunderstanding of these complex systems, as well as otherareas of materials, physics, and chemistry and diverse fieldssuch as medicine, and to enable new fields such biotechnology.Perhaps more than in any other field advances in our basicunderstanding and control of semiconductor, optical, andmagnetic materials and phenomena enable the technologythat underpins today’s so-called Information Age. Withthe continuing decrease in feature size of since the inventionof the integrated circuit (IC) more than forty yearsago, and the associated increase in transistor density andIC performance, the silicon IC has enabled the computingand communications revolution. “Moore’s Law,” theprojection that the number of transistors per square centimetreof Si would double about every 18 months [1], hasguided advances in this technology. Massive research anddevelopment efforts have enabled increases in the productivityof the Si IC at a historical rate of 25-30% per year,making low-cost computing widely available.In addition to the Si IC, major advances in communicationbandwidth and associated reduction in cost were alsorequired to enable the Information Age. Advances in fibreoptics, introduced into communications about 20 yearsago, greatly enhanced communication capability. Communicationbandwidth is increasing at an accelerated ratewith our increased understanding of optical materials andphenomena. Equally impressive is the advance in the rateof development of other optical components to permit theuse of photons to perform an increasing number of functionsthat were performed by electrons.In addition to silicon semiconductors, compound semiconductorsplay a major role in information technology.Compound semiconductor diode lasers provide the photonsfor optical communication as well as for optical storageand compact disc technology. High performance compoundsemiconductor diode lasers modulated at gigahertz(GHz) frequencies send information over the fibre opticalnetworks. Very high speed, low power consumption compoundsemiconductor electronics are key to wirelesscommunication, especially for portable units and satellitesystems. Compound semiconductors also offer an extremelyfertile field for advancing our understanding offundamental physical phenomena.Another key enabler of the information revolution is lowcost, low power, high-density information storage thatkeeps pace with the exponential growth of computing andcommunication bandwidth. Low cost, high-density storageis provided by magnetic, and to a lesser extent optical,media. Today’s highest performance magnetic storagedevices rely on giant magnetoresistance in atomicallyengineered materials.6.8.2. State of the Art in Electronic Materials and Systems(a) Silicon-based systemsTransistors with gate-lengths less than 100 nm are underdevelopment for high volume manufacturing by leadingedgesemiconductor companies. In addition, functioningtransistors with gate lengths below 20 nm have been demonstrated.The steady decrease feature size and associateddecrease in cost per function has created literally hundredsof applications for silicon ICs. Based on the InternationalTechnology Roadmap for Semiconductors [2], industryexpects to manufacture integrated circuits with gatelengths of 20 nm by 2014 (Fig. 6.13), which will requiresignificantly greater scientific understanding and controlof semiconductor materials and manufacturing processesthan are available today.Silicon-germanium (SiGe) and silicon-on-insulator (SOI)have demonstrated performance superior to transistorsand circuits based on bulk silicon and are in volumemanufacturing; however, a transition to either SiGe of SOIwill only provide a one-time gain.MATERIALS SYNTHESIS AND PROCESSING219

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART220Minimum Feature size (nm)(b) Nanostructured materialsNanoscopic and mesoscopic systems are larger thanatoms but small enough that their properties differ fromthose of bulk materials. When electron wavelengths insuch mesoscopic systems are comparable to the structuraldimensions and the mean free path for phase breaking,statistical averaging does not eliminate quantum mechanicalphenomena. This behavior has been demonstrated bysuch phenomena as universal conductance fluctuations.Results can be dramatic when electrons are confined in allthree dimensions in structures that enhance the electronelectroncorrelations to exhibit quantization of both chargeand energy. The voltage required to add an extra electroncan be used to measure the energy levels of these “artificialatoms.” These artificial atoms are large enough to displaybehavior not observed in natural atoms; for example,the superconducting energy gap in mesoscopic Al structuresis quantized.ITRS Roadmap AccelerationFig. 6.13. Comparison of the timing of the technology nodes in the 1999Technology Roadmap for Semiconductors with those in the 1994 and1997 Roadmaps. The first year for volume manufacturing is listed fortwo features: isolated gate length and DRAM half-pitch, to accommodatethe replacement of memory by microprocessors as the primarytechnology driver.In a quantum dot structure, adding an electron to the quantumdot creates a Coulomb field, which repels the additionof another electron. A single electron transistor (SET)can be realized by placing the quantum dot between theinput and output channels and adding a control gate. SETsturn on and off again each time an electron is added. Theoperating temperature of mesoscopic structures increaseswith decreasing size, and near room temperature operationhas been demonstrated in nm-size SETs and SingleElectron Memories (SEMs) (Fig. 6.14).Such devices not only function as transistors, but they alsoprovide insight into the physics of mesoscopic structures.Using the sharp peaks associated with the addition of anelectron, the equilibrium ground state energy of the dropletof electrons, as well as some low-lying excited states,can be measured. Other phenomena, such as Kondo behavior,have also been observed in these systems.In addition to the Coulomb blockade behavior discussedabove, resonant tunneling and quantum confinement canbe used to create new devices and illustrate new phenomena.In resonant tunneling, the probability for charge carriersto tunnel through barriers is greatly enhanced whenthe energy levels on the two sides of the barrier are identical.Large changes in tunneling current are realized withsmall changes in the bias voltage. Quantum confinementstructures can be created which serve as electron waveguides,conceptually similar to the waveguides encounteredin optical structures. In structures that confine electronsto regions with dimensions comparable to the electronwavelength, quantum interference effects can be usedto switch electronic currents.(c) Compound semiconductorsCompound semiconductors such as GaAs, AlGaAs, In-GaAs, SiGe, GaN, GaAlN, etc., offer intrinsically higherspeed and lower noise than silicon and have been used todevelop very high frequency electronic devices and circuitsfor microwave and wireless communication applications.Advancing the limits of semiconductor materialstechnology is essential for increasing the speed of transistorsand advancing our ability to modulate light emittingdiodes (LEDs) and semiconductor lasers at high frequenciesfor high-speed optical communication. With morethan one element, compound semiconductors offer a widerange of materials and structures with electronic and opticalproperties that are tailored through band structureengineering.Band structure engineering through the use of complexheterostructures formed from combinations of semiconductorsincreases the properties, performance, and potentialapplications. Heterostructure devices such as heterojunctionbipolar transistors, field-effect transistors, semiconductorlasers, and light-emitting diodes are formedfrom atomic layer control of epitaxial layers with differentcompositions and thicknesses. The growth of one materialon another produces materials not found in nature to createstructures with feature sizes comparable to the electronde Broglie wavelength.

Source: University of WisconsinSingle Charge Trap – Narrow channel blockedSilicon channelblocked(25 nm x 35 nm)Polysilicon GateBuried oxideSilicon substratePolysiliconquantum dotstores singleelectronInsulationlayerFig. 6.14. Single electron memory structure based on a polycrystallinesilicon quantum dot.The ability to span the broad spectral region from ultravioletto long-wavelength infrared was enhanced by the introductionof strained-layer systems. Very high crystal qualitylayers can be grown for systems with different equilibriumatomic spacing if the thickness of the layer is less than thecritical layer thickness at which dislocations nucleate andgrow. Such strained (pseudomorphic) thin layers offer anadditional degree of control over the electronic band structureof the artificially structured material.Very high performance High Mobility Electron Transistors(HEMT) were developed by creating nearly ideal twodimensionalelectron gases (2DEG) through the growth ofmodulation doped structures. Today’s highest performancetransistors, in terms of speed-power product and noise,are pseudomorphic HEMTs.6.8.3. Future Trends and Research Opportunities in ElectronicSystems(a) Si semiconductor technologyExtensive research will be required to develop new approachesto metal interconnects and new interlayer dielectricsto provide the required IC speed. Cu has replacedAl for the interconnect metallization, and low dielectricconstant insulators are being developed to replace SiO 2 .While potential candidate materials have been identifiedfor the interlayer dielectric, normal metals can only carrythe technology for a few more generations.Continued scaling of Si technology will encounter fundamentallimits as the feature sizes of the transistors becometoo small to confine the electrons in the channels. In addition,when the information is contained in only a fewcharge carriers, statistical fluctuations will limit deviceperformance uniformity. Then today’s approach to IC technologywill no longer be extendable to smaller feature sizesand higher densities, which is stimulating the search formaterials and device structures of the future.Perhaps additional performance improvements for CMOScan be obtained with SiGe on insulator. Ultimately thesame fundamental limits will be reached in these materialswith continued scaling as with Si.Major materials-related technical questions for silicon ICtechnology include: What interconnect technology will beused beyond Cu and low – i.e., beyond normal metalsand dielectrics – for Si ICs, and how do we manufacturesingle electron transistors and memories at reasonableoperating temperature and cost?(b) Nanostructured materialsQuantum dot structures are just beginning to be investigatedin depth. Circuits are being formed by collections ofartificial atoms or molecular electronic structures usingsuch approaches as quantum dot cellular automata (QCA).In today’s digital integrated circuit architectures, transistorsserve as current switches to charge and dischargecapacitors. In QCA, logic states are encoded by the positionsof individual electrons rather than by voltages. Suchstructures should be scaleable to molecular levels with deviceperformance improving with decreasing size. Questionsfor research include: What are the best approachesto understand and exploit quantum state logic?In addition to quantum dot-based single electron transistorsand memories, nanowires, in which electrons are confinedin 2-D, are being investigated for microelectronicapplications. Si nanowires can be doped either n- or p-typeto transport electrons or holes. Such doped Si nanowireshave been used as building blocks to demonstrate diodestructures consisting of crossed nanowires and bipolartransistors consisting of heavily and lightly n-doped nanowirescrossing a common p-type nanowire. Simple circuitsare beginning to be explored using these nanowires. Dopedn- and p-type InP nanowires that can function as fieldeffect transistors are being grown.Carbon nanotubes, which can be formed in either a semiconductingor metallic state, are being investigated fornanoscale microelectronics [3]. Nanowires and carbonnanotubes are ideal building blocks for nanoscale elec-MATERIALS SYNTHESIS AND PROCESSING221

DimensionDensity of StatesMAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART222Energytronics. These structures carry charge and excitons efficiently,and field-effect and single-electron transistors havebeen demonstrated in carbon nanotubes, which can beformed in either semiconducting or metallic states. Suchresearch represents the early stages of exploration of approachesto replace conventional lithographic approachesto patterning semiconducting devices and circuits with anatomic and molecular nanotechnology approach to fabricatingdevices and circuits.(c) Compound semiconductorsControlling the dimensionality of a material on the scaleof a few nanometres by growth or processing can greatlyalter the density of electronic states (Fig. 6.15) and theelectrical and optical properties.ThreeTwo20 NanometersOneEnergy Energy EnergyZeroFig. 6.15. Illustration of the effect of quantum confinement on thedensity of electronic states (From Scientific American, 8 (1) 26, 1997).A three dimensional (3-D) distribution of electrons in ametal or semiconductor has a density of available electronicstates that increases as the square root of the energy.Enclosing a thin layer of lower band gap material withthickness comparable to the electron de Broglie wavelengthbetween higher band gap materials yields a 2-Dquantum well with sharp steps in the electronic density ofstates. Confining electrons into a 1-D quantum wire producesa series of sharp peaks at the onset of each new quantummode in the wire, and confining electrons into a 0-D“quantum dot”, or a box of size comparable to the wavelengthof the electron in all directions, produces a series ofeven sharper spikes which correspond to a series of confinedquantum levels for the electrons in the box. Confiningelectrons (or holes) in three dimensions leads to giant‘pseudomolecules” with large optical nonlinearities. Suchstructures can become the basic building blocks for noveldevices. One example of a concept that is beginning to receiveattention is that of quantum state logic [4], in whicha device can be switched between multiple states, in contrastto a field-effect transistor which is either “on” or “off”.Excitons, (band-edge bound states between conductionband electrons and valence band holes) have wave functionssimilar to those of Rydberg atoms. Binding an electronor a hole, or both, in 1-, 2-, or 3-dimensions comparableto exciton diameters greatly affects the excitonic levelsand optical properties near the band gap. In theory, 3-Dconfinement (quantum dots) can produce zero thresholdcurrent lasers. Significant research is underway to understandthe phase diagram of the excitonic matter in semiconductorsand its interaction with photons.As discussed elsewhere, increased understanding of thephysics of quantum microcavities and advances in compoundsemiconductor growth and processing techniquesis also leading to major advances in optical microcavity lasers,LEDs, and detectors.(d) Organic semiconductorsAn emerging and rapidly growing area of research is thesynthesis of semiconducting organic materials. Much ofthis work has concentrated on optoelectronic devicesbased on electronically active organics, including lightemittingdiodes, thin-film transistors, photovoltaics, andnonlinear optical elements. Excitement in this area isgenerated by the ability to process organics using low-costmethods such as spin casting, micro-contact printing(stamping), and screen printing with the potential to producelarge area devices and patterns easily compatible withplastic substrates [5].The maturest electronics-related application of organicmaterials is light-emitting diodes. Understanding injectionand transport properties that determine current andvoltage characteristics are critical areas of research thatare advancing rapidly. Organic thin-film transistors withperformance comparable to amorphous silicon transistorshave been fabricated for switching pixels in active-matrixliquid crystal displays. Improved charge injection andtransport are critical to these electronic applications oforganic semiconductors.Another promising area of active organics in electronicsrelies on the conductivity of doped conjugated polymers.Doped trans-polyacetylene, while unstable in ambient conditions,has exhibited conductivity’s higher than metals.More stable systems, such as doped polypyrrole, showpromise for application as transparent contacts for displays.

6.8.4. ConclusionElectronic materials provide an active and growing researcharea, which continues to yield exciting scientificknowledge and technological advances. Although Si devicetechnology is pervasive, many research questions remain.For example, recognizing that one cannot continueto scale silicon integrated circuits to smaller feature sizesindefinitely raises the question: What is beyond Si? Someof the potential questions to be addressed to answer suchquestions include: How can self-assembled materials becontrolled to create the desired 1- 2-, and 3-D structures?How does one create hybrid structures that exploit the bestproperties of, e.g., organic or polymeric materials and semiconductors,magnetic materials and semiconductors, orsuperconductors and semiconductors?To date much of the semiconductor technology has reliedon atomic-level control of crystal growth and lithographicpatterning of devices and microstructures. One probablesuccessor to optical and electron-beam patterning forfabricating nanostructures could be atom-by-atom ormolecule-by-molecule assembly. Scanning tunnelingmicroscopes have been used to arrange atoms on surfacesand to measure changes in the energies of the surface electrons.Scanning probes have been used to construct singleatom switches, in which the movement of an atom fromone position to another opens or closes a circuit created byassembling rows of atoms on a surface.We anticipate a variety of scientific opportunities to emergefrom electronic polymers. Potential areas range from molecularelectronics, self-assembled nanostructures withgiant optical nonlinearities, hybrid structures with organicmaterials and inorganic quantum dots, and functional polymersthat can interface to biological systems. Organic materialswill be discussed in more detail in the section onPhotonic Systems, since their earliest major impact willprobably occur in optical and optoelectronic applicationsrather than in ultra-high density IC applications.Significant advances are beginning to be realized in highresolutionink-jet printing of all polymer thin film transistorsand circuits. This approach is attractive both for thelow cost of the manufacturing process but also compatibilitywith a variety of substrates because of the lowprocessing temperatures. Discovering and controlling newself-assembly approaches for low-cost fabrication on structureswith atomic-level control are important areas ofresearch that are receiving increasing attention.1.2.3.4.5.ReferencesG. E. Moore, Electronics 38 (1965) 114-116.International Technology Roadmap for Semiconductorshttp://www.itrs.net/ntrs/publntrs.nsfSee, e.g., P. G. Collins, M. S. Arnold, and P. Avouris, Science 292 (2001)706-709.C. H. Bennett and D. P. DeVincenzo, Nature 404 (2000) 247-255.J.A. Rogers, Z. Bao, K. Baldwin, A. Dodabalapur, V.R. Raju, J. Ewing andK. Amundson, Proceedings of the National Academy of Science 98(9),(2001) 4835-4840.MATERIALS SYNTHESIS AND PROCESSING2236.9. Photonic SystemsP.S. Peercy | University of Wisconsin, Madison, 53706-1691, United States6.9.1. IntroductionSince the invention of the laser in 1960, a revolution in opticalmaterials and phenomena has stimulated advanceson many fronts. This section will focus on two areas tohighlight selected advances and opportunities in opticalmaterials and phenomena: semiconductor-based and fibreoptic-based materials systems.The ability to grow devices and structures with atomic layercontrol in selected materials systems allows the manufactureof high performance, high reliability, compound semiconductordiode lasers, high speed semiconductor-baseddetectors, billions of light emitting diodes (LEDs) annuallyfor displays, free-space and short-range high speed communication,and numerous other applications. Compoundsemiconductor diode lasers provide the photons that transportinformation on optical fibres for telecommunication.Semiconductor diode lasers are also at the heart of opticalstorage and compact disc technology.Fibre optics, a relatively recent entrant into the high technologyarena, is the preferred technology for transmissionof digital information over long distances. In addition torapid growth in the amount of installed fibre, data transmissionrates in a single fibre is increasing exponentiallyby a factor of 100 every decade.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART224Luminous Efficiency (lumens/watt)6.9.2. State of the Art in Semiconductor- and Fibre Optic-Based Optoelectronic Systems(a) Lasers and LEDsWe continue to see major advances in optical microcavitylasers, LEDs, and detectors, enabled by increased understandingof the physics of quantum microcavities and advancesin III-V and II-VI compound semiconductor growthand processing techniques.Vertical cavity surface emitting lasers (VCSELS), formedby enclosing an active gain medium between two highlyreflective dielectric mirror stacks grown vertically on a substrate,offer major advances in diode laser fabrication andperformance. Full wafer fabrication and on-wafer testingoffer manufacturing improvements analogous to the manufacturingadvances integrated circuits brought to transistors.In addition, the mode pattern and high speed switchingperformance is well matched to many optical communicationsapplications.Light emitting diodes (LED) are a closely related area thatcontinues to experience major advances. Improvementsin our ability to control the quality and composition of compoundsemiconductor materials and structures combinedwith increased understanding of the science and technologyhave led to dramatic improvements in the efficienciesof red LEDs since the invention of the visible LED in 1960(Fig. 6.16). The recent development GaN and InGaN lightemitting diodes complemented wavelengths of theGaAs/AlGaAs and AlInGaP/GaAs materials systems toprovide high efficiency LEDs throughout the visible spectrum[1].Evolution of LED TechnologyFig. 6.16. Increase in efficiency and wavelengths available for lightemitting diodes in the visible spectral region since 1960 (Courtesy ofM. G. Craford, LumILeds).(b) Organic optoelectronic materialsElectronically active organic materials are an emerging areaof LED technology. A variety of organic- and polymericbasedoptoelectronic devices, including light-emittingdiodes, thin-film transistors, photovoltaics, and nonlinearoptical elements are being demonstrated. Organic materialsdesigned at a molecular level will incorporate functionalentities with the desired optical, electrical, and mechanicalproperties that are suitable for cost-effective processingschemes. The vision for semiconducting organic andpolymeric materials is large area low-cost devices resultingfrom inexpensive manufacturing methods like spray painting,ink-jet printing, dip coating, and reel-to-reel processing.Another vision driving organic optoelectronics is thepotential for low cost, flexible displays.Material stability, device performance, and low operatingvoltage remain important areas of research and engineering,along with understanding injection and transport,which determine current-voltage characteristics. Wideapplication of organic emitters in display technology requiresresolving systems issues associated with electricaldrive, patterning, and color fidelity.(c) Optical data storageOptical information is stored by forming spots or pits on areflective surface. The stored information is read by measuringthe intensity of the reflected light from a laser beamfocused onto the surface. Today’s optical recording technologyrelies on compound semiconductor laser diodes.Diode lasers with shorter wavelengths will increase storagedensity. Increased optical storage density can also beobtained with stacked semitransparent optical disk layersto produce a 3-D sandwich with laser beams focused onthe desired storage layer. The third dimension increasesdata storage areal density by an order of magnitude.(d) Quantum dot lasersConfining electrons in 1-, 2-, and 3-D produces qualitativechanges in the density of electronic states and the resultingelectronic and optical properties. Research in thisnanotechnology area has produced novel structures, includingthe quantum dot lasers in structures with 3-D confinementand novel electronic and optoelectronic devicesin structures with 2-D confinement [2].Quantum dots, with behavior similar to that of large atoms,are expected to be the basis for future devices. Quantumdots can be formed by a variety of techniques, rangingfrom patterning an appropriate substrate to self-assembly.Quantum dot lasers with good performance, formed bythe island growth that occurs in Stranski-Krastanow epitaxialgrowth of highly lattice-mismatched systems, were

first demonstrated in materials systems such as InAs onGaAs. In theory, quantum dot structures can produce laserswith zero-threshold current: all photons generatedcontribute to the laser action. Defects and distribution inthe size of quantum dots limit the performance of laserswith multiple quantum dots in the active region.(e) Quantum cascade lasersIn conventional semiconductor lasers, light is generatedby the recombination of an electron in the conduction bandwith a hole in the valence band. To first order, the wavelengthemitted by the laser is determined by the energydifference between the conduction and valence bands. Ina QC semiconductor laser, light is generated by only electrons(or holes) in transitions between two excited statesof an ultra thin quantum well. The discrete energy levelsarise from size quantization that occurs for quantum wellthicknesses comparable to or less than the electron de Brogliewavelength. The active regions of a QC laser are separatedby electron injectors that enable electrons to tunnelinto the upper excited state of the system. Electrons cascadedown an energy staircase, emitting a photon in eachactive region. N photons are thus created by a single electrontraversing an N stage device (N is typically ~ 25), yieldingmuch higher optical power than available in a conventionaldiode laser at the same wavelength.The photon energy can be tuned over a very wide range ina given material system by changing the thickness of thelayers. Initial QC lasers based on quantum wells in the AlInAs/InGaAsmaterial system demonstrated wavelengthsspanning a large portion of the mid-infrared spectrum.These devices exhibit superior operating temperature andoptical power performance compared to other semiconductorlasers emitting at these wavelengths. Single modeoperation with wide wavelength tuning, as well as activeself-mode-locking to produce picosecond pulses, have alsobeen demonstrated. Recently, QC laser wavelengthshave been extended to wavelengths beyond 20 micrometres[3].(f) Photonic band gap structuresExtending the concept of optical microcavities into threedimensions leads to photonic band gap materials [4].Structures with periodic variations of dielectric constanton a length scale comparable to the wavelength of light alterthe propagation of photons analogous to the way semiconductingcrystals alter the propagation of electrons, resultingin energy bands for which photon propagation isforbidden. However, a defect in the periodicity introduceslocalized states in the photonic band gap analogous to theway defects produce localized states for electrons withinthe band gap of a semiconductor. The nature and shape ofthe localized states depend on the dimensionality of thedefect: confinement in 1-D, 2-D, and 3-D will create mirrors,waveguides, and a microcavities, respectively. Designand manipulation of photonic lattices with such defectspromise exquisite control of photons.(g) Fibre-optic based systemsOptical fibres ushered in a new age of communication.Reduction of transmission losses were accompanied bymajor advances in electrically modulated single wavelengthsemiconductor diode lasers operating in the 1.3 and1.5 micrometre wavelength regions, fast avalanche photodiodedetectors, erbium-doped fibre amplifiers and otherfibre-based devices, and high power semiconductor diodelasers used to pump the fibre devices.Invention of Er-doped fibre optic amplifiers enabled muchsimpler systems. These amplifiers provide modulation formatand bit-rate-independent gain over a relatively widespectral region. They also provide sufficient optical powerfor high data transmission rates and wave division multiplexing.Fibre gratings formed by exposure to UV light tochange the index of refraction in the core of silica fibredoped with germania became building blocks for a plethoraof active and passive fibre devices such as filters, amplifiers,fibre lasers, dispersion compensators, pump laserreflectors, demultiplexers, and equalizers.6.9.3. Future Trends and Research Opportunities in Semiconductor-and Fibre Optic-Based Optoelectronic Systems(a) Lasers and LEDs future visionNovel approaches have demonstrated extremely high Qmicrocavities, including semiconductor-based whisperinggallery mode resonators (Fig. 6.17) or droplets of dye solutionor polymer in which the index change between thematerial and air produces a high Q waveguide around theoutside of the structure. Such ultra-high Q cavities enormouslyenhance internal fields to offer new approaches forthe study and control of non-linear optical phenomena.LEDs have long been used in displays, and high efficiencyLEDs permit numerous new applications, ranging fromvehicle brake lights to highway status and traffic controlsigns. The higher efficiency and longer life of LEDs resultin much lower operating costs compared to incandescentlights. As efficiencies continue to improve, we can expectenormous growth in the areas for application of LEDs; onecould envision large area high brightness LED arrays thatserve alternatively as a digital television screen, computerdisplay, and room lighting.MATERIALS SYNTHESIS AND PROCESSING225

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART226(b) Organic optoelectronic materialsImproved current injection and transport are needed forelectrically pumped organic lasers. Hybrid approachesusing passive organic gain media optically pumped byelectrically pumped inorganic semiconductor lasers arealso being explored.Future research will concentrate on the nanoscience andtechnology of organic materials, including current flowthrough single molecules, photochemical modification ofa single domain or small arrays of domains, synthesis ofmaterials with giant optical nonlinearities, and integrationof organic materials and inorganic quantum dot structures.Such systems hold the promise of materials which self-organizeinto complex supramolecular arrays. Self-organized3-D structures may be useful in fabricating photonic bandgap structures or color displays [5].Whispering Gallery Mode Laser(d) Quantum dot lasersBoth InAs/GaAs and molecular organic quantum dots arecapable of generating single photons on demand, importantfor quantum encryption. Study of the entanglementof coupled quantum states in closely spaced quantum dotmolecules and the creation of structures that combinequantum dot lasers and photonic lattices can be expectedto yield new exciting physics and devices. Such coupledquantum dots and structures may become important forquantum computing and information processing [6].(e) Quantum cascade lasersAlthough the first applications based on intersubband transitionswas long wavelength infrared detectors, the demonstrationof laser action based on such transitions offersthe possibility of other optical devices based on intersubbandtransitions. Intersubband quantum box (IQB) laserswith conventional mirror feedback structures have beenshown theoretically to have lower threshold current densitiesand operating voltages, which should permit higheroutput power and wall plug efficiencies, than QC lasers.We can expect other applications of intersubband transitions.Because QC and IQB lasers do not rely on recombinationof electrons and holes across the semiconductingband gap, the technology appears to have the potential tobe extended to indirect band gap materials, such as SiGe.If such extension is possible, the integration of QC or IQBlasers with Si and SiGe integrated circuits could have amajor technological impact.Fig.6.17. Scanning electron micrograph of a very high Q microcavity(Courtesy of Bell Laboratories).(c) Optical data storageApproaches to increase the storage density include nearfieldoptical recording and holographic storage. Thousandsof holograms can be recorded in a spot of a storage mediumwith resolution on the order of the wavelength of light.Three-dimensional storage of overlapping hologramspromises a projected storage density two to three orders ofmagnitude larger than conventional optical storage. Withthe simultaneous transfer of the entire image, holographicstorage also promises extremely high data rates.Approaches to the fabrication of nanowires include growthon stepped substrates formed by cutting a crystal at a smallangle to a principal lattice direction and catalyzed growthon selected regions of the substrate. Early work exploredthe GaAs/AlGaAs system for potential quantum-wirelasers. N- and p-type InP nanowires that can function asfield effect transistors can be assembled into p-n junctionsthat exhibit rectifying behavior and strong light emissionto form nanoscale LEDs, and wavelengths smaller thanthe diameter of the nanowire have been demonstrated.Since the energy states in the nanowires are affected byquantum confinement, the emission wavelength can betuned by changing the thickness of the nanowires. Suchsystems may result in one-dimensional lasers.(f) Photonic band gap structuresPhotonic lattices in the near IR and visible spectral regionswill offer a radically improved means for controlling light.Essentially zero-loss propagation is predicted, even for awaveguide bend with a radius comparable to the wave-

length of light. Low cost fabrication of photonic band gapwaveguides in the near IR and visible spectral region wouldenable manufacture and packaging of integrated opticalstructures to revolutionize integrated optical systems.(g) Fibre-optic based systemsEnormous strides toward an all-optical network are beingmade, and the emergence of low-loss graded index multimodeplastic optical fibres could lead to a low cost mediumto deliver high bandwidth communications over short linksfrom a single mode glass fibre backbone to the desktop.6.9.4. ConclusionMajor research opportunities abound in optoelectronicmaterials and devices with today’s increased scientificunderstanding and powerful scientific tools. Researchfrontiers in the optical area include artificially structuredmaterials with tailored optical properties made by epitaxialgrowth, lithography, self-assembly, and other techniques.quantum dot structures with photonic band gap materialsin the visible and near IR wavelength region. Low costassembly and manufacturing techniques such as selfassembly,stamping, and printing would have a major technologicalimpact.References1. M. G. Craford, MRS Bulletin October 2000 (2000) 27-31.2. P. M. Petroff, A. Lorke, and A. Imamoglu, Physics Today 54, (2001) 4652.3. R. Colombelli, F. Capasso, C. Gmachi, A. L. Hutchinson, D. L. Silvco, A.Tredicucci, M. C. Wanke, A. M. Sergent, and A. Y. Cho, Appl. Phys. Let.78 (2001) 2620-2622.4. E. Chow, S. Y. Lin, S. G. Johnson, P. R. Villeneuve, J. D. Jonnopoulos, J.R. Wendt, G. A. Zubrzycki, H. Hou, and A. Alleman, Nature 407 (2000)983-985.5. Y. Lu, Y. Yang, A Sellinger, M Lu, J. Huang, H. Fan, R. Haddad, G. Lopez,A. R. Burns, D. Y. Sasaki, J. Shelnutt, and C. J. Brinker, Nature 410 (2001)913-917.6. M. Bayer, Pl Hawrylak, K. Hinzer, S. Fafard, M. Korkusinski, Z. R. Wasilewski,O. Stern, and A. Forchet, Science 291 (2001) 451-453.MATERIALS SYNTHESIS AND PROCESSING227While the basic physics of charge and energy transfer inorganic and polymeric materials is well established, thepractical limits to charge photogeneration, injection, andtransport are still poorly understood at the microscopiclevel. Understanding and controlling interfaces betweenmorphologically disordered materials become increasinglyimportant as device dimensions shrink. Developing efficientlight-emitting diodes, transistors, and electricallypumped lasers will require good electrical contact toorganic materials. Improving material stability is also necessaryto make systems based on organic materials commerciallyviable. Nanostructures based on inorganic andorganic semiconductors, polymers, and other complexmaterials will form the building blocks for future devicesand systems.Research is needed to understand the coupling of excitonpolariton-phononsin nanostructures and quantum cavities,the physics of electro-optical processes in organicmaterials, and ultra fast non-equilibrium processes in semiconductors,metals, and biological molecules.Advances in such understanding, along with advances insemiconductor lasers and optical components throughoutthe visible and near ultraviolet spectral region, willresult in numerous technological applications. Otherexciting frontiers include integration of quantum wire and

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART2286.10. Ecomaterials6.10.1. IntroductionK. Yagi and K. Halada | National Research Institute for Materials Science and Technology Agency,1-2-1 Sengen, Tsukuba-Shi, JapanThe final decade of the 20 th Century has been the most importantperiod so far in preparing to create a sustainablesociety for the century ahead. The United Nations Conferenceon the Environment and Development named “EarthSummit” was held in Rio de Janeiro in 1992, and the “RioDeclaration on the Environment and Development” andits action plan “Agenda21” were declared to promote practicalsteps in preparing a sustainable society. In the sameyear, international standardization on environmental performance,such as environmental management systemsand life cycle assessments, were begun to support activitiesaiming for sustainable development. Just one year beforethe first Earth Summit, the concept of Ecomaterials(ecologically-benign materials) was proposed to encouragethe development of materials that are non-damaging to theglobal environment and place less of a burden on the planetduring production – for example, by being highly recyclable,or by making more efficient use of raw materials.1. Expansion of mankind’s frontiers by enabling new technologies.This is consistent with the traditional way of developingmaterials, in which physical, chemical, thermaland/or functional properties are improved and put touse.2. Harmonious co-existence with the ecosphere by minimizingdamage done to the natural environment.From the viewpoint of sustainable development, consumptionof materials and energy, emission of toxic gasesand waste associated with materials processingshould be reduced to ease our impact on the resourcecirculationsystem.3. Optimizing technology and infrastructure to create ahealthy life in harmony with Nature.Materials should be friendly not only to Nature but alsoto humans.In this report the challenges facing Ecomaterials are reviewedand classified in order to clarify the next steps intheir development.Co-existability with eco-sphereECOMATERIALS6.10.2. State of the ArtThe concept of Ecomaterials was born through discussionsabout the future state of materials in the service ofhumankind and their relation to the environment. Consideringthe finiteness of the Earth and the biosphere, weshould be conscious of the environmental load that ourproducts and materials place on them. Humans producematerials from raw materials taken from the environmentto expand their frontiers and make their lives more comfortable.These activities form part of the “human-system”,which interacts with the “geo-system” and “bio-system”,the latter two systems closely interacting to form the “ecosphere”.While the main interest of materials developmentwas traditionally only in the human-system, harmoniousco-existence with the other systems has become importantin recent years. Ecomaterials development takes a holisticview of the ecosphere and has three strands as shownin Fig. 6.18.naturalmaterialsOptimizabilityFig. 6.18. Concept of Ecomaterialscurrent materialsExpandability of human’s frontiersAll materials and their properties should be reconsideredfrom the viewpoint of Ecomaterials; e.g., How can a requiredproperty be obtained with less environmental load?How can materials be given improved recyclability? Howcan maximum performance be acquired with least consumptionof materials?

Type A- pollution prevention- greenhouse effectpreventionSocio-ecologicalfunctional & chemical- biodegradableplastics- greenEnergygeneration- hazardous substance free- well-bred environmental profile- higher material efficiency- higher recyclabilityType Cmechanical & physicalType B- materials fornew energy systems- materials forwaste treatment facility- materialsfor higherefficientenergy systemFig. 6.19. Three groups of environmentalapproaches to materials technology.Type AFunctionalmaterials forenvironmentalprotectionMaterials of strategicsubstitution for environmentbenign systemType CType BMaterialswhich supportlow emissionsystemsMATERIALS SYNTHESIS AND PROCESSING229Since the concept of Ecomaterials was proposed, manyresearch projects on materials associated with environmentalissues have started in Japan, such as the nationalresearch project entitled “Materials design and assessmenttechnology for development of Ecomaterials”. Manyresearch groups and courses have been set up around theworld, with the result that various Ecomaterials have beendeveloped, and four international conferences on Ecomaterialshave been held since 1992.6.10.3. Expected BreakthroughsSince environmental issues are world-wide and concernevery human activity (the major ones being pollution frommining, acidification by factory and vehicle emissions, thegreenhouse effect resulting from combustion of fossilfuels, water pollution, and toxic substances present inwaste) fundamental improvements in the materials we useare needed to safeguard the natural environment. Theapproaches of materials technology to improve the environmentcannot be generalized from one viewpoint. Theycan be divided into three categories based on the relationbetween a material’s properties and its role in improvingthe environment:A. Functional materials for environmental protection;Materials properties are optimized to improve eachenvironmental problem.B. Materials supporting low-emission systems;Materials properties are needed to support environmentallybenign systems.C. Materials of strategic substitution for an environmentfriendly social system;Materials are used for a given property but societydemands that they have lower environmental burden.These categories are shown in Fig. 6.19.Catalysts for cleaning up toxic waste, alternative materialsto replace toxic substances, CO 2 -absorbing substances,and so on belong to the first group (Type A: EnvironmentalFunction Type). The second group (Type B: System-ElementType) consists of materials for energy-saving or newenergy systems, such as high-temperature turbine blades,

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART230thermoelectric materials, low-temperature steel pipes forhydrogen transportation, and superconductors. The thirdgroup (Type C: Strategic Substitution Type) consists ofmaterials strategically substituted for materials that placemore of a burden on the environment. This group is theEcomaterials in a restricted sense. Ecomaterials havecreated a new field for materials-designers with the strategicapproach of substituting currently-used materials withmaterials placing less burden on the environment throughouttheir lifecycles.The coming paradigm of post-mass production is oftencalled Dematerialization. According to Dematerialization,what one wants is to become aware not of the productitself but of the service mediated by products. In this case,materials can be circulated mainly among producers andservice providers. In the coming era, materials technologywill become more important, because we have to circulatematerials and products with higher quality in an adequatefashion. Materials should be characterized by 1) lowerenvironmental loading, 2) flexibility in production, 3) longlife and the possibility of progressive maintenance. Theseaspects should be maintained throughout the life cycle ofthe material via a proper life-cycle design.The requirements of environmentally benign life-cycle designof materials are 1) connection with other industriesfrom the viewpoint of industrial ecology, 2) selection ofmaterials of less environmental load, 3) flexibility for DfE(Design for Environment), 4) no harmful substances afterdisposal that would make the material a liability after itsuseful life is over, 5) easy to recycle. These materials willbe used as a kind of “material leasing system” which leadsus toward a recycling-based dematerialized society.6.10.4. Roadmap for Future Research(a) MLCA (Materials Life Cycle Analysis)Ecomaterials of Type I and Type II have relatively cleartargets for development and assessment. A means of measuringthe degree of benignity of a material is required.MLCA has to be developed to feed the environmental lifecycleconsiderations back to materials design. MLCA isdeveloped from LCA to evaluate how well a material qualifiesas an Ecomaterial by considering the following differencesbetween a material and its products;1) The life cycle of a material is different from that of itsproducts. Materials can be used many times by recycling,prolonging the total life cycle.2) A material has broad generic utilization. The usage stageof a material has wide variations, while that of a productis more specific.3) Materials properties are sensitive to composition andmicrostructure.While materials are classified roughly in LCA of products,differences of composition and of microstructure shouldbe considered in detail to feed back and improve materialsdesign, which is the technology to estimate microstructural/compositionalparameters correlated with materialsproperties.A database for MLCA also has to be constructed containingrepresentative inventory data of processing of each elementalmetal and ferrous alloy. The environmental history,namely accumulated emissions of associated processesfrom mining to processing, of each alloy and a recyclabilityparameter will be obtained by accessing this database.(b) Recyclable materials designAlmost all traditional alloys contain many additive elementsto improve their properties. The additives frequentlyhinder recycling. Traditional materials technology,which has been developed starting from natural resources,cannot treat man-made impurities well. This disadvantageis one of the main reasons for the low cost-competitivenessof recycled material. A new approach toimprove recyclability is to control the properties not byelement but by structure.Forming a dual phase steel of martensite and ferriteresulted in improvements in both strength and toughnesswithout adding any other elements. Thermomechanically-treatedAl-Si has a dual spherical structure. This structureenables easy forming of recycled Al-Si alloys.(c) Development of various types of ecomaterialsThe development of Ecomaterials can take three approachescorresponding to the way each type of material is to beused. They are classified into four categories from a tech-Field of diffusive materialsMaterials of mass-consumption with useful functions• materials without harmful substances in theusage and disposal stages– Pb-free solder, Alternative materials to asbestos,Alternatives to PVC, Plastics with harmless fireretardants, Olefin laminated steel sheet substitutefor PVC, etc.

nological viewpoint; 1) harmful substance-free type, 2)low environmental profile type including materials fromrecycled resources and from natural resources, 3) recyclablematerials and 4) materials for efficient energy flow.These approaches have been expanding the area of environmentallybenign materials from the stage of “end ofpipe” or “mouth of” to the total stages of the life cycle,namely “smart” pipe.In the field of diffusive materials, where a great amount ofmaterials are consumed daily for the useful function of thematerial itself, substitution of harmful substances to reducethe environmental burden during and after usage ismainly focused; such as materials for batteries, wrapping,soldering, paints, etc.As the amount of materials used for construction projectsand large-scale infrastructure is enormous, the environmentalload “from cradle to grave” of these materials isgreat. Another side to these materials is their recyclability.Since these materials are relatively easy to manage, thepossibility of recycling these materials appears high. Theapproaches for Ecomaterials in this area are listed in thefollowing table.Field of high volume materialsMaterials for structural usematerials with lower environmental profiles “fromcradle to grave”• materials with less rare materials and with less energyconsumingmaterials• materials from nature– wood-based materials– wood-ceramic– soil ceramics• materials from waste– cement from municipal waste (eco-cement)– cement from ash– various new materials from waste• circulated materials– steel with artificial impurities (tramp elements)– reconfiguration of used wood• materials processed with less emissions andenergy consumptionmaterials with high recyclability• recyclable designed alloys– steels with less number of elements– common aluminium alloy– alloys robust for impurities• recyclable designed plastics• recyclable designed composites– ecomposable composites• composites of same family materialRecyclable designed steel, eco-cement and wood-ceramicsare typical results in this field. Recyclable designedsteel, which was mentioned before, is not only recyclablebut also contains less metallic elements, which are rareand energy consuming to process. Eco-cement is cementmade from municipal waste. Eco-cement not only reducesthe mining of limestone and other resources but alsoreduces the waste to be released to the environment aftertreatment. Wood-ceramic is a new porous carbon materialobtained by carbonizing wood or woody materialimpregnated with phenol resin using ultrasonic vibrationin a vacuum furnace. Wood-ceramic has a cellular structureof glassy carbon, which provides good heat resistance,thermal-shock toughness, small thermal expansion,chemical stability, many infrared effects, and so on, withoutusing many man-made materials such as advancedceramics or plastics.Field of energy transmission materialsMaterials for power generation and transmission(the major environmental burden is generated at theusage stage in the life cycle)• materials with higher performance in the usage stage– high-strength steels for automobiles– heat resistant alloys for high temperature turbines• light weight alloys for vehicles– Al alloys for automobiles– Mg alloys• other materials designed for LCA oriented usageThe third field is that of materials related to energy transmission,transportation and so on, namely those related toenergy consumption at the usage stage. Effective propertydesign of materials is used in the development of materialsfor power transmission media. For example, high-tensilesteel sheet reduces the weight of automobiles by 4%resulting in 1.2t less CO 2 being produced during the lifecycleof a car in Japan.6.10.5. Positions in Japan, the U.S. and EuropeInternational conferences on Ecomaterials have alreadybeen held four times. Last year an Ecomaterials symposiumwas held in Ottawa, Canada. The 5 th conference willbe held on 2-5 October this year. In the U.S., the NSF produceda report on research into “Environmentally benignmanufacturing”. The Industrial Ecology group has heldtwo meetings, and the next meeting is planned for theNetherlands this November. As a practical internationalMATERIALS SYNTHESIS AND PROCESSING231

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGARTcollaboration, the “Handbook of Ecomaterials” is in preparationwith the cooperation of many researchers fromEurope, Japan, Canada, U.S., China and others.In 1999, VAMAS (The Versailles Project on Advanced Materialsand Standards) approved an initiative on environmentalstandardization activities for materials technologyentitled “Definition of a Role for VAMAS Participation inEnvironmental Standardization Activities for MaterialsTechnologies”. International collaboration in Ecomaterialsresearch is expected to be promoted more and more inorder to find ways of solving materials problems and establisha sustainable society.6.10.6. ConclusionsIn this paper, the state of the art, expected breakthroughsand a roadmap for Ecomaterials research were described.More fundamental research and new ideas are needed inorder for these materials to receive widespread use in thenear future.232ConclusionsFirstly it should be recognized that having knowledgeof potentially advantageous intrinsic properties of acompound/alloy is one thing, but that converting thisknowledge into a viable, i.e. practically useful processingroute is another thing, which often proves to be extremelydifficult, if possible at all. This leads to the following firstmain conclusion:• Whereas significant attention can be paid to the design/prediction of new materials, the major effort should bedevoted to the development of successful processing routes.Considering, as an example, metal-alloy production, it isclear that the treatment starting with the casting of theraw material and continuing with a combination of heattreatment and deformation, is all-decisive for realizing theproperties sought for. This treatment defines and optimizesthe internal structure, the so-called microstructure,in terms of atomic arrangement and morphology of theconstituents. In other words:• Control of the microstructure is the key to successfulmaterials processing.In this sense, reviewing the state of knowledge in allmaterial classes of some significance, it is concluded that• More basic, fundamental knowledge on processes controllingthe microstructure (grain morphology and size, phaseconstitution, texture, stress) is imperative. Lack of suchknowledge is the limiting factor on progress in virtuallyevery area of modern materials engineering.This holds for the production of thin films and the area ofsurface engineering in general, as well for the productionof all kinds of composites and bulk materials, both inorganicand organic. To summarize the current impression:it is felt, in contrast with what one may naively presume,that:• The gap between fundamental knowledge and technologicalapplication has increased in recent years. Hence,basic science on model systems for practical materialsshould be promoted.Control of the mechanisms prevailing on the atomic andmolecular scale is necessary, but also on a larger lengthscale the course of a transformation/reaction should bedescribed quantitatively. For example, quantum mechanicalcalculations on the molecular scale can be useful, buton a mesoscopic length scale (i.e. at lengths of the orderof the size of a crystal grain) for example continuummechanical calculations (on the basis of finite elementapproaches) have to be performed.

Special emphasis today is placed on small-scale structures:thin films and nanoparticles. The synthesis of nanoscalematerials is more an art than a science; “nanoresearch”is often conducted on ill-processed materials. Thisis a recurrent theme in the contributions on thin films, inorganicmaterials, ceramic materials and composites containedin this chapter. Again, the role of the microstructuremust be emphasized in this context: one of the unsolvedproblems encountered in the sintering of nanosizedparticles is the preservation of the extremely small grainsize in order to maintain favourable (mechanical) properties.The key to progress in these areas is better materialsprocessing.Expected breakthroughs in the field of materials processingcan of course be formulated as the breaking of thebarriers which obstruct what is not possible at present.Examples can be found in the contributions of this chapter.Yet, it should be recognized that real breakthroughs inboth science and technology very often occur unplannedand are frequently not the aimed-for outcome of a correspondinglydedicated research strategy. Therefore:It may be advantageous to aim for a European centre ofexcellence on materials processing. The background ofthis remark is the recognition that it can hardly be expectedin the near future that single institutions will possessthe full range of, for example, thin film technologies andcomposite materials processing techniques. Also, concentrationof expertise on materials processing can accelerateprogress in research in this area. However, it shouldbe noted that in order to achieve genuine understandingof the mechanisms underlying the processing of materials,basic understanding of the reactions and phase transformationsinvolved is required. This, then, would be thefocus of the research in other centres of materials science.Therefore a centre on materials processing may best be avirtual one, composed of a number of research groups inEurope which have intimate contact. This form of organizationbrings about the necessary cooperation and availabilityof techniques for all researchers in the groupswho take part in the centre and it encourages cooperationwith materials scientists not participating directly in thiscentre, who investigate the basic aspects of the reactionsand phase transformations of the materials of interest.As a final remark it is observed that environmental aspectsare important as well. This is partly more a politicalmatter than a scientific one. Once society has expressedcertain demands, science can contribute. This leads toadditional constraints on the conditions for a successfulmaterials processing route, without altering any of theconclusions above.MATERIALS SYNTHESIS AND PROCESSING233• Although materials processing is naturally strongly relatedto applications of materials in practice, a substantialpart of the research in this area should be curiosity drivenand not application driven.As specific focal points of interest one may indicate:• A (perhaps the) major development in materials processingwill be defect elimination and cost reduction(this holds particularly for composites).• The trend will be to niche markets for materials withtailored properties (e.g. development of multicomponent,possibly functional gradient materials often with anisotropicand non-linear properties).

CHAPTER 77. ADVANCED ANALYSISOF MATERIALS234235Advanced materials science is striving for the designof dedicated materials and dedicated materialssystems with tailored and often optimized properties.As a prerequisite this task requires detailed informationon the microstructure* of a given material (or materialssystem) on all length scales ranging from atomistic sub-Ångstrøm to macroscopic dimensions. On the other handthe characterization of properties (mechanical, electrical,magnetic, and chemical) must be possible with high accuracyand reliability. One important aspect of materialsscience is to correlate the microstructure to the propertiesof a given material (or materials system). One essentialtask of Basic Research in Materials Science is, in fact, tounravel such laws and relationships in condensed materialsand reveal theoretical model for the rationalization ofthe structure-property relationship. With such rigorous orsometimes empirical structure-property relationshipsavailable new materials (or materials systems) can beconceived in applied materials science for advanced noveldevices.▲*The term "microstructure" is used in the sense that it encompassesdescriptions of the structure of all phases in the material itself and ofall lattice defects present in the material, e.g. interstitials, vacanciesin non-thermodynamic equilibrium, dislocations, domain boundaries,grain boundaries and interfaces.Microstructure of a SiC ceramic (transmission optical micrographobtained with polarized illumination, U. Täffner, MPI für MetallforschungStuttgart).IntroductionProgress in basic research in materials science is, thus,strongly dependent on the development of powerfulanalytical techniques which provide us with all necessarystructural and microstructural information. From a fundamentalpoint of view a material is characterized by itsatomic and electronic structure, with this in hand, advancedtheories would, in principle, be able to predict asan example, its mechanical or dielectric response. In thischapter we primarily focus on the fundamental analyticaltechniques which are often based on large-scale facilitiesand thus depend on a sustained European science policy.Traditionally, three different analytical approaches are distinguishedfor the characterization of the microstructure:diffraction, microscopy (imaging) and spectroscopy. Analysisby X-ray and neutron diffraction provides an averagestructural information. The diffraction techniques aremost sensitive to long-range correlations within the materialwhere the dimension of the correlation length shouldexceed the dimensions of the X-ray (neutrons) beam. Complementary,microscopy imaging yields local informationwith high spatial resolution which reaches sub-Ångstrømresolution. The electron microscopy techniques are, therefore,most suitable for the determination of the (local)structure of lattice defects such as dislocations and grainboundaries. By spectroscopy elementary excitations canbe investigated in the materials, such as the electronicband structure, phonons or magnons. Again spectroscopywithin a transmission electron microscope (analytical electronmicroscopy) provides those entities with high spatialresolution.In the last two decades unexpected breakthroughs in X-ray-diffraction and -spectroscopy have been achieved withthe availability of highly brilliant synchrotron radiationsources which provide the user with an X-ray beam which

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART236can be tailored in size, energy, coherence, polarization andtime structure. The prominent European source is the EuropeanSynchrotron Radiation Facility (ESRF) in Grenoblewhich has started operation in 1994. ComparableX-ray sources are the Advanced Photon Source (APS) inChicago and SPring-8 in Japan.Neutron-diffraction and -spectroscopy has developed intoa most powerful technique which is complementary toX-rays and particularly useful for magnetic and soft materialsas polymers and H-based structures and for the studyof the dynamical behaviour of materials. Between the 50sand 70s powerful neutron research reactors have beeninstalled worldwide. The European neutron source, theHigh-Flux-Reactor (HFR) of the Institut Laue Langevinin Grenoble, has started operation in 1972. Because of thelack of public acceptance and political support of reactorbasedneutron sources, one is facing today a neutrondraught: Many neutron research facilities have been closedworldwide, today, the new neutron source “ForschungsreaktorMünchen II” (FRMII) in Garching (Germany) isthe only new research reactor under construction. Oneway out of this problem are Neutron Spallation Sourceswhich do not produce nuclear waste and do not suffer fromthe damaged image of neutron reactors. The Europeanproposal for such a new neutron source is the EuropeanSpallation Source (ESS) project which would provide apulsed neutron beam with a peak power which is factor100 higher than the HFR allowing access to new dynamicdomains in soft and magnetic materials.In several areas the advantages of X-ray and neutron scattering/spectroscopyare complementary, in some areas theydirectly compete. Each probe has its strength in the applicationto different classes of materials. Neutron scatteringis well established in the field of polymer science, organicsystems and the study of stress/strain states in industrialmachine components, whereas synchrotron X-ray scatteringstill has to find widespread use in the applied communitybesides its already strong acceptance in proteinscience and drug design.It is characteristic for structural as well as for functionalmaterials that their properties are governed by structuralfeature on various length scales, ranging from the micrometerscale to the sub-Ångstrøm scale. In addition, the timescales which control the dynamic processes and responsesof the systems range from several 10 5 seconds to the subpicosecondregime. The analytic control of these lengthand time scales poses serious challenges to basic researchin materials science.The main drawback of diffraction techniques in materialsscience has been so far the rather moderate lateral resolution.Information can only be reached with a spatial resolutionof several micrometres at best. If, however, the microstructureis non periodic and alters with much smallerlength scale (e.g. at grain boundaries, etc.) this spatial resolutionis not sufficient for the analysis of lattice defects.Advanced transmission electron microscopy techniquescan provide extremely valuable information for the latterproblem, for example on the structure, composition andbonding of regions adjacent to lattice defects.Imaging of materials is a traditional field in materialsscience. Optical microscopy has been pushed to the limit.By near-field optical microscopy sub-diffraction resolutioncan be achieved. However, much better spatial resolutioncan be achieved by electron microscopy. Electronmicroscopy is an extremely important technique since realmaterials are mostly polycrystalline and grain boundariesoften control the properties (mechanical, electrical) of ma-

ADVANCED ANALYSIS OF MATERIALS237terials. The fractions of “grain boundary volume” to the“bulk volume” is highest for nanocrystalline materials. Theproperties of grain boundaries control the properties of thebulk. Furthermore, materials are often heterogeneousexhibiting a variation of local structure which may determinethe materials properties. This is especially true forthree-dimensional nanomaterials where the diameter ofthe characteristic crystalline feature is only a few nanometresin size.Imaging of materials on all interesting length scales is possibleby advanced instrumentation ranging from advancedoptical microscopes to scanning electron microscopes, andother surface science instruments, and, especially, transmissionelectron microscopes. The detailed analysis oflocalized structures is the domain of high-resolution transmissionelectron microscopy (HRTEM) which providesstructural information of materials at the atomic level.Recent revolutionary instrumental developments inHRTEM resulted in the availability of corrector elementswhich allows to overcome fundamental aberration of electronoptical imaging systems. It is expected that the structuralanalysis of lattice defects and even non-periodic materialscan be done with extreme precision of the (average)position of individual atoms or – in crystalline materials –of columns of atoms. Local spectroscopic information fromregions about 1 Å in diameter can be retrieved from electronenergy loss spectroscopy (EELS) investigations.These measurements result in a better understanding ofthe variation of local properties within a material. It shouldbe achievable to probe and locate the weak links of materials.It is essential for the further development in Europethat such instruments are available in specific centres anddifferent laboratories. Owing to the complexity of theinstruments the specimen preparation technique and theinterpretation of structural as well as spectroscopy informationrequires a real and/or virtual network withinEurope, and, especially a number of Centres of Excellence.NMR is particularly powerful for the analysis of the localstructure of noncrystalline materials, as amorphous materials,liquids and biological materials. For the atomic-resolutionimaging of surfaces scanning tunneling microscopy(STM) and atomic force microscopy (AFM) are used nowadaysin a somewhat routine way, though, the reliable quantitativeinterpretation of STM and AFM images is still anart which needs experience and training.Over the last 40 years the control of coherent radiation asprovided by lasers has rendered visible and infrared lightinto a most powerful tool for scientists and technologists.Today coherent light is available with terawatt peak powerand femtosecond pulse structure revolutionizing scienceas a whole, but also advancing into many technological andmedical areas. Femtosecond laser spectroscopy allows onetoday to obtain a realtime insight into the dynamic behaviourof the electrons in materials which opens up a newfield of electron spectroscopy. The investigations of structureand function of new materials by ultrafast techniques,nanooptics and a combination of both will be a centraltopic of future basic research. In addition to the analysis ofultrafast phenomena, optical control of ultrafast processesmay become an important issue for realizing specificfunctions. Simultaneously, technological applications inoptoelectronics and information technology are driven bythe need for higher data transmission rates and fasterinformation processing, requiring all-optical techniquesfor modulation and switching. Material processing withultrashort pulses represents another promising field ofapplication.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART2387.1. X-Rays (Synchrotron Radiation)J. Schneider | DESY-HASYLAB, 22603 Hamburg, GermanyG. Kaindl | Institut für Experimentalphysik, FU Berlin, 14195 Berlin, GermanyC. Kunz | European Synchrotron Radiation Facility, 38043 Grenoble, FranceH. Dosch | Max-Planck-Institut für Metallforschung, 70569 Stuttgart, GermanyD. Louër, | Université de Rennes, 35042 Rennes, FranceE.J. Mittemeijer | Max-Planck-Institut für Metallforschung, 70174 Stuttgart, Germany7.1.1. State of the ArtPhoton beams play an increasingly dominant role in thecharacterization of materials from the atomic to the macroscopicscale, with the photon spectrum ranging from thefar-infrared to the very hard X-ray region. This is particularlyso, since the construction of many dedicated synchrotron-radiationfacilities in most of the technologicallyadvanced countries in the eighties, and especially theappearance of third-generation synchrotron-radiationfacilities in recent years, has enormously expanded theclassical means of characterizing materials. Since we arenow at the threshold of introducing even fourth-generationsources, namely the free-electron X-ray lasers, thisprogress will continue, and eventually lead to a merging oflaser-based and synchrotron-radiation-based methods inmaterials research.progress makes it particularly difficult for industrial companiesto keep pace with the fast development of the analyticpotential of this field. In contrast to the wide spreadopinion of industrial managers, it is not complicated togain access to synchrotron facilities. At these facilities oneis aware of the great industrial potential one wishes to integrate.Applications and remuneration usually come intoconsideration only when commercially relevant data areprovided. Fig. 7.1 shows the European Synchroton Facility(and the High-Flux Neutron Reactor) in Grenoble.The present situation in the field of synchrotron-radiationresearch in Europe in comparison to the U.S. and Asia canbe described as follows: Europe has played a leading rolein the development of the field, starting from the pioneeringwork at DESY in the early seventies, the constructionof early dedicated XUV-sources, like BESSY and ACO inthe eighties, up to the creation of more modern third-generationsynchrotron-radiation sources in the nineties, likeESRF, ELETTRA, MAX II, BESSY II, and the Swiss LightSource. Europe is again leading in the construction of freeelectronX-ray lasers, like the TESLA Test Facility at DESY,Hamburg, and there are further new facilities in variousEuropean countries in planning and under discussion, inparticular those in England and France. In Europe morethan 10 000 scientists and engineers make use of synchrotronradiation at different locations shown in Table 7.1.Synchrotron-radiation based research is very often basicscienceoriented, and even though there is a great potentialfor applied research, this section has often beenneglected. The reasons for this are manifold, at least partlybased by the rapid methodological progress of the field,which again is a consequence of the rapid progress in theperformance of synchrotron-radiation facilities. The rapidFig. 7.1. ESRF (European Synchrotron Radiation Facility) and High-FluxNeutron Reactor of the ILL (Institute Laue-Langevin) in Grenoble,France (courtesy ESRF, Grenoble).7.1.2. MethodsFor space reasons, we can mention only a selection of thevarious synchrotron-radiation-based methods for characterizationof materials that have been established to highlevels of perfection at different laboratories. They provideinformation on the spatial structure of the materials, onthe chemical and electronic structure, on microstructure,on magnetism and on the properties of surfaces, interfaces,thin films and multilayers. The investigations allowextreme variations of the sample environment, from low tohigh temperatures and from ultra-high vacuum pressurein the range of 400 GPa.

Location Ring (Institute) Electron Energy [GeV] NotesGrenoble ESRF 6 DedicatedOrsay DCI (LURE) 1.8 DedicatedSuperACO (LURE) 0.8 DedicatedSOLEIL (LURE) 2.5 - 2.75 Planned/DedicatedBerlin BESSY 1.7 - 1.9 DedicatedBonn ELSA (Bonn University) 1.5 - 3.5 Partly dedicatedDortmund DELTA (Dortmund Univ.) 1.5 Dedicated / FEL useHamburg DORIS III (HASYLAB/DESY) 4.5 DedicatedPETRA II (HASYLAB/DESY) 7 - 14 Partly dedicatedKarlsruhe ANKA (Res. Centre Karlsruhe FZK) 2.5 DedicatedFrascati DAFNE 0.51 ParasiticTrieste ELETTRA (Synch. Trieste) 2 - 2.4 DedicatedDaresbury SRS (Daresbury 2 DedicatedDidcot DIAMOND (RAL) 3 Planned/DedicatedBarcelona LLS (Univ. Autònoma Barcelona) 2.5 Planned/DedicatedAarhus ASTRID (ISA) 0.6 Partly dedicatedASTRID II (ISA) 1.4 Planned/DedicatedLund MAX I (Univ. of Lund) 0.55 DedicatedMAX II (Univ. of Lund) 1.5 DedicatedVillingen SLS (Paul Scherrer Institut) 2.4 DedicatedADVANCED ANALYSIS OF MATERIALS239Table 7.1. European Synchrotron Radiation SourcesIn structure research, classical powder diffraction can nowbe performed with an angular resolution that providesenough highly resolved reflections for ab initio structuresolutions in excess of 30 independent atom positions perunit cell. Crystal sizes can be determined up to 1 µm. Stressand strain analysis with high spatial resolution can be performedon iron-based samples of up to 15 mm thickness.Current efforts in synchrotron-based powder diffractionfocus onto the 3D-imaging of strain in single grains exploitingthe recent achievements in X-ray microbeams andX-ray focusing.Element-specific chemical information is obtained fromcore-level photoelectron spectroscopy and X-ray absorptionof near-edge fine-structure (XANES) spectroscopy,since highly monochromatic X-ray and XUV beams can betuned to the various photon energies of interest. Powderdiffraction and XANES spectroscopy allow followingchemical reactions in real time with a rate of a fraction ofa second. The electronic structure can be determined ink-space using angle-resolved photoemission and X-rayemission spectroscopy with a similar time resolution.Different aspects of magnetism can be investigated andanalyzed in great detail with various magnetic dichroismtechniques in X-ray absorption, X-ray reflection, photoemission,and X-ray emission as well as with magneticX-ray diffraction. Resonances at the X-ray thresholds allowdisentangling the individual contributions of the elementalconstituents to the total magnetization. Resonant magneticX-ray diffraction has been pushed to provide magnetic-structureinformation on ultrathin films with a thicknessas low as 10 monolayers. Other powerful methods forthe study of magnetic materials include spin-resolved photoemissionand nuclear resonant scattering, two methodsthat benefit a lot from the new intense X-ray beams.Microscopic techniques such as soft and hard X-raymicroscopy, photoemission microscopy (PEEM), X-raymicroprobeanalysis, and phase-contrast imaging aredeveloped continuously to better spatial resolution andto a higher accuracy. Resolution limits between 1 µm and20 nm have been achieved, depending on the technique.Some of these techniques provide also chemical and magneticcontrast. Tomographic reconstruction of compositematerials, foams, and inhomogeneous samples can beobtained with 1 µm resolution.7.1.3. Special Focus: X-Ray Powder DiffractionX-ray powder diffraction is widely applied for the characterizationof crystalline materials. The method has beentraditionally used for phase identification, quantitativeanalysis and the determination of structure imperfections.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART240In recent years, applications have been extended to new areas,such as the determination of crystal structures and theextraction of three-dimensional microstructural properties.The method is normally applied to data collected underambient conditions, but in situ diffraction as a function ofexternal constraints (temperature, pressure, stress, electricfield, atmosphere, etc.) is important for the interpretationof solid state transformations and materials behaviour. Variouskinds of micro- and nano-crystalline materials can becharacterized from X-ray and neutron powder diffraction,including inorganics, organics, drugs, minerals, zeolites,catalysts, metals and ceramics. The physical states of thematerials can be loose powders, thin films, polycrystallineand bulk materials.Phase identification is traditionally based on a comparisonof observed data with interplanar spacings, d, and relativeintensities, I, compiled for crystalline materials. The PowderDiffraction File, edited by the International Centre forDiffraction Data (U.S.), contains powder data for morethan 130 000 substances. New search/match proceduresare based on digitized patterns instead of a list of differentvalues of d and I, respectively.aFig. 7.2. (a) Microfocus beamline ID13 at the ESRF;(b) Picture of 3D topography of a metal foam.Quantitative phase analysis involves the determination ofthe amounts of different phases present in a multi-componentmixture. The powder method is widely used to determinethe abundance of distinct crystalline phases, e.g.in rocks and in mixtures of polymorphs, such as zirconiaceramics. Modern approaches are based on the Rietveldmethod. Because of the potential health hazard of respirablecrystalline silica, X-ray powder diffraction is also usedfor identifying and quantifying silica of all types of samplesfrom airborne dusts to bulk commercial products.bAmong the most noteworthy advances of the powder methodis the determination ab initio of crystal structures from powderdiffraction data (to date more than 400 successful exampleshave been reported). Here the resolution of the patternis of prime importance. In addition to X-ray sources, neutronsalso play an important role in powder diffraction structureanalysis, e.g. in case of too low atomic contrasts for X-raysand for precise refinement of atomic coordinates. Neutronpowder diffraction was used to determine the oxygen contentand position in high T c superconducting cuprates.Powerful methods are available for pattern indexing,extraction of integrated intensities, structure solutionand refinement of the structure model with the Rietveldmethod. New direct space methods for crystal structuredetermination have been introduced, e.g. Monte Carlosimulated annealing, genetic algorithm, crystal structureprediction by energy minimisation and molecular modelling,etc. These techniques are promising approaches,even in case of molecules with several torsion angles.A promising approach is based on combining NMR, electrondiffraction and powder diffraction by X-rays.Microstructural imperfections, such as lattice distortions,stacking and twin faults, dislocations and crystallite sizedistributions, are usually extracted from the shape of individualdiffraction lines. Recently, profile modelling (synthesis)techniques have extended the frontiers of microstructuralinvestigations. They include the effect of crystallitesize distributions, the effect of lattice distortion parametersand the effect of strain fields in crystalline materials.Time- and temperature-dependent X-ray diffraction involvesthe in situ measurement of series of diffraction patternsas a function of time and temperature. It is possibleto establish the reaction path during solid state transformationsand to determine transformation kinetics: e.g. theinvestigation of fast and self-propagating solid combustionreactions on a subsecond time-scale, using synchrotronradiation for high intensity. The time required for collectingdata decreases considerably with the availability of fastdetectors, such as position sensitive detectors, and highbrightness of modern (Synchrotron) X-ray and neutronsources. Equipment has been developed for in situ applicationof heating, pressure and tensile testing. In situ powderdiffraction can also be combined with complementarytechniques applied simultaneously, such as EXAFS(Extended X-ray Absorption Fine Structure).Breakthroughs are expected in the following areas:(i) Microstructure analysis. The precise characterizationof the microstructural properties of “real” materials willbecome possible.

Synchrotron Radiation Techniques (Selection)Application; TrendsMicro-beam diffractionRoutine operation down to 2 µm, sub-µm in testingMagnetic X-ray diffractionElement specific; film thickness less than 10 monolayersPowder diffraction Real time; ultra-high-resolution (see Sect. 7.1.3.)Anomalous small angle X-ray scatteringElement specific, high-resolutionX-ray absorption fine structure (XAFS)Element specific coordination shellsHigh-energy X-ray diffraction Stress and strain of bulk samples; texture –high spatial resolution, 3D tomography of large samplesInelastic X-ray scattering Electronic excitations, elastic response –element specific, small samples, high pressureNuclear resonant scatteringLocal magnetism at high pressure; small samplesX-ray micro-tomographyPhase contrast imaging; submicron spatial resolutionTime-resolved spectroscopy and diffractionS dynamics of catalytic reactions; fs with XFELX-ray microscopy (hard and soft)30 nm resolution possible; 10 nm envisagedMagnetic dichroismHigh potential for magnetic multilayersUHV Surface diffractionOxidation at catalytic surfacesXANES spectroscopyChemical reactions – element specific in real timeADVANCED ANALYSIS OF MATERIALS241Table 7.2. Recent Developments in Synchrotron Radiation Applications.(ii) Stress analysis. The analysis of macro-stresses by powderdiffraction analysis gives new impulses to understandthe elastic and plastic interactions of grains in massivespecimens.(iii) Crystal structure analysis. More complex structureswill be solved using more powerful software and methodsto be developed in the future.(iv) In situ diffraction. Studies of materials under ‘working’conditions and experiencing dynamic microstructuralchanges will become of paramount importance to understandmaterials performanceThere are many laboratories using powder diffraction on aprimitive level. A European network should be developed,with the help of the existing EPDIC (European PowderDiffraction Committee) to train researchers and technicalstaff in order to perform high-quality experiments and evaluations.EPDIC is organizing a conference series in modernpowder diffraction. The International Centre of DiffractionData (ICDD) is an U.S. organization. Only relativelyrecently in Europe the European Committee forStandardization (CEN/TC 138) started an extensive projecton the use of diffraction methods.7.1.4. Needs and TrendsX-ray and neutron diffraction at large scale facilities techniques,see table 7.2, are now established through pioneeringexperiments. Only a few of these novel and powerfultechniques find a community, which makes regular use ofthem as a standard tool in materials research. Even thoughmany of the researchers working on materials becomeincreasingly aware of these methods, many of them needa specific support to access the synchrotron-radiationfacilities and to make optimal use of the opportunitiesprovided there.There are several reasons for the time gap between the developmentof powerful new synchrotron-radiation-basedanalytical methods and their actual use in materials research.Besides the rapid progress in the field mentionedabove in Sect. 7.1.1, one of the reasons has to do with thefact that many of these new and advanced methods are developedby physicists, while those involved in materials researchare mostly chemists or engineers. Therefore, oneshould bring the two communities together.Experimental techniques have been pushed to new frontiersalready with the introduction of 3 rd generation of synchrotronsources. These trends will be enhanced evenmore strongly with the coming XFEL 1 . Spatial resolutionachievable nowadays by microdiffraction and imaging isapproximately 30nm with a future limit below 10nm. Acombination of spectroscopy and diffraction is going to beapplied to all categories of diffraction experiments by movingto the absorption edges of specific elements andenhancing greatly the sensitivity for selected elementseven for the smallest sample dimensions. The trend for1) XFEL: X-ray free electron laser

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART242time-resolved measurements is now in the picosecondrange, but the real need in material science lies in the femtoseconddomain, which will be achievable with the XFEL.The exploitation of the coherence of the new sources willset new trends in allowing a simultaneous combination ofmicroscopic length scales with macroscopic ones.7.1.5. MeasuresThe measures supported by the European Community tocounteract and improve the described situation shouldhave in mind to (i) enhance and spread the knowledgeabout these powerful novel techniques in materials researchin the community and (ii) to ease the access to thefacilities. However, the involvement of university groupswith their young and dedicated researchers is of crucialimportance, because they guarantee progress and will helpto counteract stagnation and frustration.To enhance and spread the knowledge about synchrotronradiation-basedanalytical techniques in materials researchthe following measures are proposed:• Support of interdisciplinary networks “Application Labfor Analytics with Synchrotron Radiation in Materials Research”,which should be administered by a leading researchgroup not directly connected with a synchrotronradiationfacility. Such Application Labs would provideeasy access to the most advanced techniques, bringingboth application-oriented users and basic-science-orientedresearchers together.• Creation of fellowships for doctoral students and postdoctoralscientists, particularly for students from thoseEuropean nations that do not possess national synchrotron-radiationfacilities by themselves. These fellowshipsshould allow dedicated and gifted graduate/postgraduatestudents in materials research or solid state science to joinleading groups at other European universities and researchcentres that are heavily involved in synchrotron-radiationresearch with easy access to beam time.• Support of special European workshops and conferenceswith the aim to bring the materials-research and basicscienceoriented communities together to exchange thepotentials of synchrotron-radiation-based research inmaterials science and development.The access to the facilities has to be eased, particularly fornon-specialized scientists, who do not want to get too muchinvolved into the techniques, but just want to use them fortheir development purposes. Special measures have to betaken at the synchrotron-radiation centres themselves.Most centres are presently organized in a way to supportonly relatively experienced users of synchrotron radiation,a situation that is not very helpful for the use of standardizedmethods of characterization with high throughput. Atspecific beamlines of SRC-Daresbury, DESY-HASYLABand the ESRF industrial users pay for shifts of beamtimeand experienced personnel to support them. In orderto achieve a similar opportunity for the non-industrialmaterials science community, the following measures areproposed:• Support of specific “Local contact for materials characterization”of this community at relevant synchrotron-radiationfacilities, staffed with personnel (scientists, engineers)that are experienced both in the use of synchrotronradiation and in materials science. Those staff people ofthe synchrotron source should be the primary contacts formaterials researchers from the different institutions in theEuropean community.• European measures should be taken in the field of the applicationof powder diffraction methods to “real” materials.• A network of tabletop X-ray lasers with XFELs as technologydrivers should be developed. This could help toavoid a long timelag between innovation and applicationas is the case for the established synchrotron sources. Theneeds of the materials science community should bebrought to the attention of the synchrotron scientist at anearly stage as input into the development process of newbeam stations. The largest impact of LINAC driven X-rayFEL facilities to materials science may well come from thevery high peak brilliance in flashes of only 100 femtosecondsduration, which allows to study the time developmentof non-equilibrium states of matter. Also very specificways of processing novel materials may come up. Unfortunatelyit will need probably another 10 years beforemulti-user facilities up to the needs of the materialsscience community will be available. In addition, difficultnew experimental techniques have to be developed, e.g.pump & probe experiments in the femtosecond time scale,including synchronising the appropriate detectors. Suchtechnical developments can only be successful if laboratorybased sources with the proper time structure and sufficientpeak flux or brilliance is available for the individualresearch group. Such equipment will also be most importantfor preparation of novel experiments finally plannedto be performed at the XFEL facility. In recent yearstremendous progress has been made in laser technology,especially in higher harmonics generation and with plas-

ma X-ray lasers, the peak intensities produced are gettingclose to the needs for materials science as described above.Therefore an EC network focussed on the developmentof novel approaches to study materials in their non-equilibriumstates with X-ray lasers, both tabletop and LINACdriven FELs, should become of very high benefit for materialsscience as a whole.7.2. NeutronsReferences1. TESLA, The Superconducting Electron-Positron Linear Collider with anIntegrated X-Ray Laser Laboratory, Technical Design Report Part V TheX-Ray Free Electron Laser (2001), ISBN 3-935702-04-3.2. R.L. Snyder, J. Fiala and H.J. Bunge (Eds.), Defect and MicrostructureAnalysis by Diffraction, Oxford University Press, 1999.ADVANCED ANALYSIS OF MATERIALSD. Richter | IFF Forschungszentrum Jülich, 52425 Jülich, GermanyK.N. Clausen | Risø National Laboratory, 4000 Roskilde, DenmarkH. Dosch | Max-Planck-Institut für Metallforschung, 70569 Stuttgart, Germany2437.2.1. State of the ArtEurope operates at present the two premier neutron scatteringfacilities in the World, namely the High Flux ReactorILL (Institute Laue Langevin) in Grenoble and thePulsed Spallation Source ISIS in the UK. Europe also operates13 smaller local sources shown in Table 7.3. Thesize of the neutron scattering community in Europe is ofthe order of 4500 scientists.Initially neutron scattering was entirely a method exploitedand used by physicists. Today instrumentation is availablefor a much broader usage as it can be seen in Fig. 7.3.A recent survey revealed that about 20% of the users areworking in materials science.Chemistry26,9%Materials Science19,4%Life Sciences3,6%Engineering Science2,9%Earth Science0,9%Physics46,3%Fig. 7.3. The exploitation of European neutron scattering scienceacross the major scientific and technological disciplines (From theENSA Survey of the Neutron Scattering Community and Facilities inEurope - an ESF/ENSA publication ISBN 2-912049-00-8, 1998).7.2.2. MethodNeutrons have a considerable advantage for texture andmicrostructure studies because they give an accurate bulkaverage, whereas techniques with small sampling volumesmay only sample a few grains.The production process for certain materials (for exampledensification in powder metallurgy, precipitate growthdrawing of fibres, grain kinetics during annealing) may bestudied in real time and in situ by scattering methods,in order to understand and control materials processing.The behaviour of materials under operational conditionsare another important issue, where problems like the dischargeof batteries, ion conduction in fuel cells, the actionof catalysts, or aging processes may be investigated. Finally,interfacial properties are gaining increasingly moreattention, with broad implications for protective coatingsand corrosion, lubrication and adhesion, functional layers,biocompatibility, and other topics.During the last twenty years, the understanding of soft materialshas been significantly advanced by small angle neutronscattering (SANS), combined with labeling throughthe H-D replacement method, and by neutron spin echo(NSE) spectroscopy, thus facilitating the determination ofthe properties of substances on mesoscopic length andtime scales. Today, SANS is the pre-eminent techniquefor determining polymer conformations, with importantimplications for, among others, chain deformation and rubberelasticity, polymer brushes stabilizing colloids, or forchains at interfaces relevant for gluing, etc. Fig. 7.4a showsthe experimental setup of a small angle scattering beamline.An experimental result obtained with SANS can be

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART244Location Source (Institute) Power (MW) NotesPrague LVR-15 (NPI, Czech Republic) 10Europe ESS 5 Pulsed source; proposal submittedGrenoble HFR (ILL, France) 58 Continuous sourceSaclay Orphee (LLB,France) 14 Continuous sourceBerlin BER-2 (HMI, Germany) 10 Continuous sourceJülich FRJ-2 (KFA Jülich, Germany) 23 Continuous sourceGeesthacht FRG (GKSS, Germany) 5 Continuous sourceMunich FRM-II (TU Munich, Germany) 30 Continuous sourceBudapest BNC (KFKI, Hungary) 10 Continuous sourceKjeller JEEP2 (IFE, Norway) 2 Continuous sourceSwierk IAE (Poland) 20 Continuous sourceMoscow IR8 (Russia) 8 Continuous sourceEkaterinburg IWW-2M (Russia) 15 Continuous sourceGatchina WWR-M (PNPI, Russia) 18 Continuous sourceDubna IBR2 (JINR, Russia) 2 Pulsed source (fission)Studsvik R-2 (NFL, Sweden) 50 Continuous sourceVilligen SINQ (PSI, Switzerland) 1 Pulsed sourceDelft HOR (IRL, TU Delft, The Netherlands) 2 Continuous sourceAbingdon ISIS (RAL, U.K.) 0.16 Pulsed source (plans for upgrade)Table 7.3. Neutron Sources in Europe.seen in Fig 7.4b. Multicomponent systems may be studiedby contrast-matching techniques and tasks like the explorationof micro-heterogeneity in multiblock copolymers orinterfacial reactions may come into focus. Dynamic experimentswith NSE provide insight into molecular rheology.uniaxially strainedpolymer networkbe investigated. The response of soft materials to externalfields like shear, temperature or pressure, is another areaof interest, with clear technological implications, such asan understanding of processing methods such as drawing,spinning, etc. of various materials including rubbers. Complexfluids in confined geometry may be accessed, allowing,e.g., an exploration of techniques for tertiary oil recovery.Neutron reflectometry is the technique of choice forstudying the morphology of artificial membranes, interfaces,films, or for studying, among others, lubrication,interdiffusion phenomena and adhesion.Recently, the application of scattering techniques to engineeringproblems has drawn much attention with a continousgrowth. At present the main areas of interest are stressdetermination in the interior of bulk materials and thediagnostics of material treatment and processing.aFig. 7.4. (a) Small-angle neutron scattering beamline KWS2 at the FRJ-2, Jülich, (b)Two-dimensional wavevector dependence of the structurefactor of SANS yields detailed structural information on global andlocal topologies on different length scales, ranging from the radius ofgyration to the tube diameter or smaller.Another challenging research field is the self-organizationof multi-component systems, like amphiphilics in oil orwater, where structural, kinetic and dynamic aspects canbFrom space-resolved diffraction measurements one obtainsthe stress in the interior of a sample. The knowledge of thestress in machine components (for example, in the vicinityof welds) is important in determining how far the materialis from yielding. Another application is the in situ investigationof the redistribution of atoms by thermal diffusion,e.g., in a turbine blade. This method can help determinethe lifetime of critical mechanical components. The correspondingdiagnostic methods are diffraction or small anglescattering. An exciting potential new application would beto use diffraction to follow heat treatment, to optimize the

thermal treatment process. Stress, as well as the grain orientation,would have to be measured as a function of timein different regions of a machine component. The processof forging could be investigated in a similar way.The main methods are diffraction, specialized for texture andstrain analysis, and small angle scattering. A recent and veryattractive development is neutron tomography, for example,for imaging hydrogenous fluids in the interior of machinecomponents, and structural reinforcement of concrete.Neutron Scattering Techniques (Selection)Small angle neutron scattering (SANS)Neutron TomographyMagnetic neutron diffractionPolarized neutron diffractionInelastic magnetic scatteringPolarized neutron reflectometryDiffractionPowder diffractionStress-strain scanningInelastic neutron scattering(Time-of-flight, Triple-axis, Spin-echo)Neutron scattering is and will always be an intensity limitedtechnique, and it is the intensity, which in general limitsthe exploitation of neutron scattering. New instrumentationat existing sources will advance the capabilities inthe same way as demonstrated with the third and fourthring in Fig.7.5. A true leap forward will be the result of thethird generation neutron sources. i.e. there will be roomfor development in all areas of materials science mentionedabove. Experiments, which are marginally possible today,will be routine and new areas or more complex systemswill be open to neutron scattering with stronger sources.Application & TrendsRoutinely used in Material ScienceRoutinely used in Material ScienceStandard method for magnetic structure analysisComplex magnetic structures; ferromagnetismExchange coupling, magnetic anisotropyMagnetic multilayers, magnetic roughness;magneto-electronics, spin valvesHighly sensitive to oxygen, carbon, hydrogenMagnetic samples; light elementsRoutinely used in Material ScienceFast ionic conductors; hydrogen storage and sensing;dynamics of polymers and glassesADVANCED ANALYSIS OF MATERIALS245Table 7.4. Recent Development in the Application of Neutron Scattering.A compact overview of the very diverse range of sciencestudied with neutrons from the early days in the sixties untiltoday is summarized in the fan of Fig. 7.5.7.2.3. Trends and NeedsEurope faces the imminent closure of several aging researchreactors. The only new facility being built in Europeat present is FRMII reactor in Munich. This reactor will bean optimized second generation neutron source which to alarge extend will replace other facilities being phased out.On the other hand the U.S. and Japan are at this momentpreparing to alleviate their local “neutron droughts” throughmajor investments in third generation advanced neutronsources, and are thereby posing a very serious challenge toEuropean supremacy in the field. The American SNSsource is a 2 MW spallation source, which will be in operationby 2006. The Japanese spallation source is not finallyapproved yet. In Europe a group of 13 laboratories from11 countries is preparing a proposal for a 5 MW spallationneutron source ESS (European Spallation Source).The FRMII reactor in Munich, is urgently needed by thematerials science community. A possible long delay ofits startup would be very costly both in terms of moneyand loss of highly qualified personal and user base. Strongsupport from the EC is needed to overcome the presentpolitical hurdles.In the long-term, a powerful new, pulsed neutron source isneeded to keep the strong European neutron scienceefforts competitive with the U.S. and Japanese efforts.7.2.4. MeasuresIt takes 7 to 10 years to build a new neutron source. Thecost of a new facility is of the order of 1 Billion €. It is thereforeimminent that Europe agrees on building the ESS –a third generation neutron source. With a decision to buildthe ESS by 2001-2002 - funding for engineering designand prototyping will be needed from 2002-2003 andconstruction could begin at the earliest in 2003, with anoperating source in 2010.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART246Fig. 7.5. The neutron fan –The first ring are from thesixties and the following fromthe 70s, 80s and 90s respectively.The outer ring is a summary offields where neutron scatteringis used as an important diagnosticstool.Other measures supported by the European Communityto counteract and improve the described situation shouldhave in mind to (i) enhance and spread the knowledgeabout the powerful novel techniques in materials scienceand in the community and (ii) to ease the access to thefacilities. However, the university groups with their youngand dedicated researchers should be centrally involved,because they guarantee progress and will help to counteractstagnation and frustration.To enhance and spread the knowledge about neutronbasedanalytical techniques in materials research thefollowing measures are proposed:• Support of interdisciplinary networks “ApplicationLaboratories for Analysis with Neutron Scattering inMaterials Research”. The laboratory should be administeredby a leading research group not directly connectedwith a neutron scattering facility. Such ApplicationLabs would provide easy access to the most advancedtechniques, bringing both application-oriented usersand basic-science-oriented researchers together.• Creation of special fellowships for doctoral and postdoctoralstudents, particularly for students from thoseEuropean nations that do not possess national neutronscattering facilities by themselves. These fellowshipsshould allow dedicated and gifted graduate and postgraduatestudents in materials science or solid statescience to join leading groups at other European universitiesthat are heavily involved in neutron scatteringresearch with easy access to beam time.• Support of special European workshops and conferenceswith the aim to bring different communities inmaterials science and basic science together toexchange the potentials of neutron scattering-basedresearch in materials science and development.To make access to the facilities easier, particularly fornon-specialized materials researchers, who do not wantto get too much involved into the techniques, but justwant to use them for their development purposes, specialmeasures have to be taken at the neutron scattering centresthemselves. Most centres are presently organizedin a way to support only relatively experienced users,a situation that is not very helpful for the use of standardizedmethods of characterization with high throughput.In order to improve the situation for the non-industrialmaterials science community, the following measures areproposed:

• Support of specific “Local contacts for materialscharacterization” of this community at relevant neutronscattering facilities, staffed with personnel (scientists,engineers) that are experienced both in the use ofneutrons and in materials research. They should be theprimary contacts for materials researchers from thedifferent institutions in the European community.7.3. High-Resolution MicroscopyReferences1. A twenty years forward look at neutron scattering facilities in the OECDcountries and Russia, Technical report by T. Springer and D. Richter, ESFand OECD (1998) ISBN 2-912049-03-2.2. Scientific Prospects for Neutron Scattering with Present and FutureSources, ESF report (1996), ISBN 2-903 148-90-2.3. ESS, A Next Generation Neutron Source for Europe Vol. II The Scientificcase (1997), ISBN 090 237 6 500, 090 237 6 608.ADVANCED ANALYSIS OF MATERIALSM. Rühle | Max-Planck-Institut für Metallforschung, 70174 Stuttgart, GermanyK. Urban | Institut für Festkörperforschung, Forschungszentrum Jülich, 52425 Jülich, Germany247Contributor:C. Colliex (Lab. de Aimé Cotton, Université Paris Sud,91405 Orsay Cedex, France).Direct imaging of materials has always been an importantaspect of microstructural characterization. There are varioustechniques for different wavelengths and instruments,namely, optical microscopy (wavelength in the range ofthat of visible light) scanning electron microscopy (SEM)and transmission electron microscopy (TEM) (wavelengthin the Ångstrøm or sub-Ångstrøm range) [1]. While opticalmicroscopy is a rather mature technique, SEM andTEM have undergone major developments and advancementsover the past decade. These advances have beenmade possible by revolutionary progress in instrumentation.It is now feasible to correct fundamental aberrationsof electron optical instruments. In addition, it is now possibleto generate coherent electron sources. Improveddetection systems exist which allow the detection of eachelectron. Furthermore, advancements in the understandingof elastic and inelastic scattering of high-energy electronsby crystalline and non-crystalline materials lead toa quantitative understanding of the collected data.In this chapter only transmission electron microscopy willbe considered. Other new and advancing imaging techniqueswill be covered in Chapters 7.4 and 7.5.A major goal in materials science is the imaging of materialsat the atomic level. This requires instrumentationallowing the theoretical and practical achievement ofatomic resolution [2]. Resolution in the Ångstrøm rangecan be reached by systems which use coherent waves of ashort wavelength and are equipped with imaging lenseswith sufficiently small aberrations. Atomic resolution ofthe bulk material is so far mainly achieved by TEM. So faratomic resolution can either be reached by increasing theelectron acceleration voltage (at constant aberration) or byspecific techniques which allow to eliminate indirectlylens aberrations by complex procedures (Table 7.5 [3]).However, recent developments in instrumentation allowthe correction of aberrations [4]. With the latter revolutionarydevelopment aberration-free imaging should bepossible in the sub-Ångstrøm range.Elastic and inelastic scattering of electrons occurs in aspecimen irradiated with electrons. Both types of scatteredelectrons can be utilized for the structural and chemicalanalysis of the materials and can be obtained with highspatial resolution.It is expected that a major breakthrough is within immediatereach regarding quantitative high-resolution transmissionelectron microscopy (QHRTEM) for the investigationof both the structure and composition of materialswith very high spatial resolution.7.3.1. State of the ArtTransmission electron microscopy has made outstandingcontributions to materials science with respect to the characterizationof the microstructure of materials [2]. Thiscovers not only structural aspects but also aspects of thecomposition of materials. The study of the microstructureof crystal lattice defects and interfaces is essential for

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART248Methods Advantages Problems Complexity CostHVEM Available now Radiation damage (?) Maintenance $10M + building +Interpretability Detectors Building service contract +Large space in lens gaptechnician salariesLocalization ofelectron beamFocus Variation Convertibility Increased Dose C s must be known Full microscope packageTechnique Processing time to less than 1% ~$1.5MOff axis Holography Convertibility Limited specimen area Biprism fabrication Full microscope package(near thin edge) & operation ~$1.5MC s must be knownto less than 1%STEM UHV environment Contrast/dose rate 300 kV - $2MMicroanalysis 100 kV - $1MDirect interpretationHigh field Stability Not available yet Lens fabrication (Developmental Costs)Needs new materialsCryogenicsRestrictive geometriesOperationMicro Lenses Size Not available yet Interpretation (Developmental Costs)CostRestrictive geometriesReflection ModePenetrationC s -Correctors Flexibility Imminent, but not yet available Needs FEG High developmental costs (>$3M)Absence of low frequenciesotherwise incremental ($100k)Point projection Lensless Interpretation Tips Moderate ($100k)Field sensitivityTable 7.5. Different approaches for extending atomic resolution microscopy [3].understanding the physics of structural as well as functionalmaterials. Contributions by TEM have been madein semiconductor technology of electronic device materials,in high-temperature superconductivity as an examplefor functional materials, and the mechanical properties of(a) coherent imagingElectron Beam(b) incoherent imaging(Z-contrast)Electron BeamScangrain boundary fracture and failure for structural materials(for either single phase materials or composite materials).There exist different paths for high-resolution imaging(Fig. 7.6). Coherent illumination (Fig. 7.6a) of the specimenwith a fixed beam results in coherent scattering of allatoms of the illuminated area of the transmitted specimen.The exit wave at the exit surface forms by interference ofthe coherently scattered electrons. The most critical lensfor this system is the objective lens, which generates thefirst image of the imaging lens system of the microscope.InterfaceObjectInterfaceAnnularDetectorSpectrometerObjectZ-contrastImageI~Z 2CCD-EELSDetectorFor incoherent illumination (Fig. 7.6b) a small probe (assmall as possible) is formed by the illuminating systems.Fig. 7.6. Image formation in a high-resolution transmission electronmicroscope: (a) Coherent imaging (left column): The specimen isirradiated with a coherent electron beam (beam diameter larger thaninteratomic distance). At the lower foil surface the amplitudes andphase fields of the different scattered waves are formed. The aberrationof the lenses modifies the wave field. The quality of the imagedepends strongly on the contrast transfer function [2]. (b) Incoherentimaging (right column). The specimen is transmitted with a stronglyfocussed electron beam (beam diameter smaller – if possible – thanthe interatomic distances). The beam is scanned over the specimenand the signals detected arriving at a large angle annular detector.The chemical analysis is performed by a spectrometer. Compared tocoherent imaging the contrast transfer function is rather simple. Theimage interpretation for both imaging techniques is not trivial [2].

The elastically scattered electrons are detected on a largeangleaperture. The probe is scanned over the specimenand the intensity of the scattered electrons is determinedsimultaneously. The most critical lens represents the probeforming system.A very active demand for high-resolution electron microscopy(HRTEM) comes presently from the rapidly developingfield of electro-ceramic materials where e.g. defectrelateddielectric losses and the atomic perfection of internalinterfaces are critical issues. The structure of grainboundaries in SrTiO 3 has been analysed by HRTEM, oneexample is shown in Fig. 7.7.For structural and compositional investigations by TEMthe quality of electron optics is limited so far by intrinsicaberrations of electro-magnetic fields forming the lensesfor electrons. Although aberration corrected systems arestandard in light optics since the beginning of 20th century,it is only recently that the feasibility of corrected electronoptics could be demonstrated. In 1998 it was shownby a German research group [4] that the primary resolutionof an ordinary commercial 200 kV TEM equippedwith a field emission electron source can be almost doubledfrom 0.24 nm to 0.13 nm. The quality of the electronmicroscope images is significantly improved by compensationof the spherical aberration of the objective lensby means of an electro-magnetic hexapole lens system.Similarly, electron optical elements which correct sphericalaberrations for the probe forming lenses in a scanningtransmission electron microscope (STEM), reduce thediameter of the incoming beam of about 2 Å at the presentto less than 1 Å in the very near future [5].With respect to HRTEM imaging, impressive results couldbe obtained on the structure of (internal) grain boundariesand interfaces between dissimilar materials. The positionof columns of atoms can be revealed with an accuracy of≤ 0.3 Å depending on the nature of the composition of thecorresponding columns. One example of the interfacebetween Cu and -Al 2 O 3 is shown in Fig. 7.8.Analytical electron microscopy (AEM) uses inelasticallyscattered electrons for the determination of the compositionof small cylinders within the material. The diameter ofthe cylinders (beam diameter) ranges from about 0.5 nmto 1.0 nm in a dedicated STEM. The inelastically scatteredelectrons contain information on composition, coordinationand bonding of atoms. The structure and chemicalcomposition in such a cylinder (including the account ofbroadening of the electron beam due to scattering processeswithin the specimen) can be determined with high precisionby electron energy loss spectroscopy (EELS). Energyloss near-edge structures (ELNES) reveal local featuresin the band structure of unoccupied states with high spatialresolution [2]. In principle, this can be also be obtainedfrom regions at interfaces, dislocation cores and otherstructural defects. Information on bonding at those defectscan be gained. So far, however, the beam diameter exceedsthe interatomic distance at grain boundaries or interfaces.Therefore, contributions of the bulk material are includedin the spectrum, making it very tedious to get informationon bonding just from the area of the defect in the material.ADVANCED ANALYSIS OF MATERIALS249 Fig. 7.7. HRTEM image of a highly symmetrical twin grain boundary inSrTiO 3 [3 (111)]. Coherent image recorded in projection. The insetat the top shows an enlargement of the framed region at the bottom.By quantitative evaluation of HRTEM images the positions of the atom(ion) columns near the grain boundary plane were determined with anaverage precision of 0.015 nm. (From Kienzle et al. phys. stat. sol. (a)166 (1998) 57).It is expected that the bonding across defects can be extracted.However, sufficient spatial resolution and energy resolutionis not yet attainable. This is also due to the low transmissivityand dispersion of the spectrometer. The presentcommercially available energy resolution of the dispersivecomponent is in the order of 0.7 eV. Such a description doesnot allow the distinction of details of the spectrum since essentialfeatures are convoluted by the low energy resolution.Advanced instrumentation with an energy resolution in theorder of 0.2 eV is required and will be obtained soon.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGARTsince the scattering process and image forming processwithin a specimen is highly non-linear, which often meansthat the position of strong contrast features does not coincidewith the (projected) positions of atoms or columns ofatoms. The determination of the reliability (error bars) isobtained by shifting the atoms in the model configurationand calculating the image again. Significant deviationsbetween experimental intensity distributions and the newlyformed model configuration result in the error bars.7.3.2. Future Visions for Transmission Electron Microscopy250Fig. 7.8. HRTEM image of the atomically abrupt Cu/(1120)Al 2 O 3 interfacetaken along the [112]Cu zone axis. The HRTEM studies were performedon a JEOL JEM ARM 1250 microscope operated at 1250 kV with a pointresolution of 0.12 nm. Image simulations assuming Cu-Al bonds atthe interface as found by EELS studies exhibit a projected bondingdistance of (0.15 +/- 0.02) nm to the first O-layer in the Al 2 O 3 substrate.(From Scheu et al. phys. stat. sol. (b) 222 (2000) 199).An important analysis technique is electron spectroscopicimaging (ESI) [6] where inelastically scattered electronswith a certain value of energy loss are used for imaging thespecimen. This technique allows the element-specificdetermination of the distribution of different elementswithin a specimen. An energy loss is selected which is justbeyond a characteristic absorption edge of the elementin the energy loss spectrum. So far mainly qualitativelyinteresting results, especially for nanomaterials, could besuccessfully obtained.A quantitative evaluation of HRTEM micrographs and analyticalstudies (especially by ELNES) requires the comparisonof experimental observations with the results ofsimulations (Fig. 7.9). This is very important for HRTEMExperimental StudiesHREM MicrographComparison(Image Processing)Atomistic Model(Projection)ModellingFig. 7.9. Quantitative evaluation of HREM micrographs.?Simulated ImageDue to the availability of corrector elements for sphericalaberrations there will be a revolutionary step for the furtherdevelopment of TEM with respect to atomic, structuraland spectroscopic resolution. Advanced instruments presentlyunder development will allow a spatial resolutionin the 0.7 Å regime. Enormous efforts are being made toensure the stability of an instrument so that no externaldisturbances (variations in high voltage and lens currents)and environmental effects (electromagnetic stray fieldsand mechanical vibrations) impair the theoretically achievableresolution of the instrument. In addition, high demandsare imposed on ideal specimens since contamination anddeviations of the atomic flatness of surfaces may result influctuations which disturb the wavelength. The deliveryof such instruments for high-resolution imaging (200 kVwith field emission gun) is scheduled for 2003 (SATEMproject of the German Science Foundation).In addition, the combination of TEM with EELS for localanalysis of elements in compounds and ESI will be availablewith instruments having a spectroscopic energy resolutionin the range of 0.2 eV and with a spot size in theorder of ~2 Å. The prototype of the (so-called) SESAM(Sub-eVolt-Sub-Ångstrøm Microscope) instrument [7]will become operational in 2002. The combination of highlocal structural resolution in space with high spectroscopicresolution in energy will provide science and technologywith direct access to the local electronic properties inatomic dimensions. The spectroscopic energy resolutionin the range of 0.2 eV permits to distinguish betweendifferent electronic valence states and provides access toimpurity states and bonding at interfaces which is relevantfor both structural and functional materials. Preliminaryresults of spectroscopy at the nearly atomic level is shownin Fig. 7.10 which depicts the column-by-column spectroscopyof a grain boundary in SrTiO 3 doped with Mn [8].However, for this experiment the approximate diameterof the electron probe was larger than the diameter of theprojected columns of the materials.

The advanced instruments have in-column energy filterswith a high transmissivity allowing imaging modes in whichsolely electrons which have experienced a specific energyloss are used to form an image. Hence, element selectiveimaging is available. This provides the researcher withchemical maps of the investigated sample material whichalso possess high lateral resolution.aIntensity (arb.units)141210864Owing to the huge development costs the electron opticsindustry requires the backing provided by a sufficient numberof orders to reduce the commercial risk to a manageablelevel. This requires supraregional procurement programmes.The stimulus for industry to develop the newtechnology for the benefit of all future potential users goesparallel with the early availability of the new instrumentsfor those whose orders were placed early. The core componentsof aberration corrected microscopes and spectrometresare produced in rather small companies whosecapacity is limited. Only a relatively small number of instrumentscan be manufactured at a time. Delivery timesof the order of three years or more are realistic, simply dueto limited manpower in development and fabrication.Therefore, an element of the international competition ofusers will be their respective position in the pipeline oforders. The first procurement programme funded by theGerman Science Foundation (Deutsche Forschungsgemeinschaft)together with the State of Baden-Württemberg,the Max-Planck-Society and the Helmholtz ResearchCentre at Jülich will lead to a first generation of commercialaberration corrected and high-precision spectroscopyinstruments. The experience with these instruments willprovide a solid basis for the funding and efficient operationof an improved second generation of instruments, to bepurchased and disseminated in a European-wide framework.ADVANCED ANALYSIS OF MATERIALS2510.2 nmFig. 7.10. (a) Z-contrast image of a Mn doped 36.7° tilt grainboundary in SrTiO 3 .The structural units, which are similar to dislocationcores, and locations of the probe where spectra were taken, areindicated. (b) The EELS spectra from the indicated locations afterbackground subtraction show differences in the chemical content andthe near edge structure from different atomic columns at the grainboundary. (From Duscher et al. phys. stat. sol. (a) 166 (1998) 327).The art of in situ experimentation was widespread duringthe period of high-voltage electron microscopy in theseventies and eighties. In fact the pole-piece dimensionsof a 1000 kV transmission electron microscope are intrinsicallylarger compared to those of a classical 200 kVinstrument. By now in situ experimenting in high-voltagemicroscopes has essentially disappeared mainly due to theuncertain effects of the radiation damage introduced intothe materials by high-energy electrons. It is to be expectedthat a new generation of dedicated, aberration corrected200 kV instruments, which are much less expensive andfit into a normal laboratory room, will bring about a renaissanceof in situ experimenting. Not only that a fairly highresolutionis available for the in situ observations duringspecimen treatment, e.g. deformation, heating, cooling orwhile the specimen is in a controlled gas atmosphere orin an electronic function, the instrument’s spectroscopicaccessories will permit immediate analysis of the statestraversed or of the products. In addition, the recent progressin micromachining and micromechanics, in particular onthe basis of silicon, permits entirely novel micromanipulationdevices. Hence, a new generation of dedicatedaberration-corrected transmission electron microscopesoptimized for in situ experiments will provide materialsscience and technology with fascinating new and uniquepossibilities for dynamic investigations in the nanometreandsub-nanometre regimes.20550600 650Energy Loss (eV)7.3.3. Needs and Trends in Electron Microscopy TechniquesRecently, breakthroughs have been achieved in themicroscopy techniques described in this chapter: The correctionof lens aberration with advanced instruments leadsto a marked improvement in resolution of all types of electronmicroscopy techniques. Furthermore, the possibilityof generating small probes in the sub-Ångstrøm regionallows the chemical analysis with atomic resolution.It is expected that the improved instrumentation (Fig. 7.11)will lead to impressive new results in materials science.However, there is still the need for continued education inthe area of electron optics and imaging techniques, anarea that is slowly disappearing in Europe. Furthermore,the interpretation of the results obtained requires theoreticalstudies of the investigated systems. This will lead to anunderstanding of structure, composition and bonding onthe atomic level.New frontiers will be reached with the introduction of thenext generation of TEMs. Expected results are summarizedin Table 7.6.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART252Materials Applications• atomistic and electronic structureof grain boundaries in electronicmaterials• bonding at hetero interfaces• segregation• mapping of valence states..?Sample Preparation• uniform thickness• material stability• sample quality• functional properties(bonding, stress, application,…)Instrumental Improvementsoverall stability (current, high voltage, mechanics)energy resolutionFEG(∆E ≤ 0,2 eV)Monochromatorprobe size(ø < 0,1 nm)imaging resolution(∆d ≤ 0,09 nm)transmissivitydetection quantumefficiencyCondenser LensC s -CorrectorObjective LensSample StageObjective LensC s -CorrectorProjector Lens 1EnergyFilterProjector Lens 2HAADFCCD, image plateMaterials Properties• energy resolution:defect statesimpurity statesband gapsphonons• spatial resolution:single atom columnsstructure of defects• transmissivity:structure of amorphous materials• in situ sample stages:functional properties( …)Theory• image contrast for highly coherentillumination• fine details of crystallographic andelectronic structure• qantitative interpretation of imageintensitiesFig. 7.11. Properties and Implications of the Future Transmission Electron Microscope.Problems to be solved by Advanced TEMBond charge distribution in crystalline materialsInterface scienceDefects by deformation and irradiationPhase transformation and alloy designNanostructured materialsSurfaces and thin filmsMicroelectronic materials and devicesStructure of amorphous materialsStructure of confined amorphous materialsTable 7.6.There are urgent measures to be taken by the EC within the6th Framework Programme in order to support and coordinatethe different activities in Europe and to link the differentinstitutions together. It is also important that advancementsmade in different laboratories are made availableto all interested research groups. It is also expected thatresearch centres similarly to those for X-ray studies, areestablished where state-of-the-art instruments are operated.In addition, theoretical investigations require the establishmentof centres which are strongly collaborating with theoreticalgroups to compliment the experimental studies.The following measures are proposed:• Support of European interdisciplinary networks on transmissionelectron microscopy techniques in materialsscience. These networks should include all leadingresearch groups in this area with a constant exchange ofthe latest advancements in instrumentation, interpretationand theoretical modelling.• Application laboratories should be established thatprovide easy access to state-of-the-art techniques. Thefunction of such laboratories would also be combinefundamental and applied research.• There is a strong need for continued education in electronoptical imaging. This field is rather mature. However,recent developments show that it is essential that theactivities in theoretical optics will continue over the nextdecades. These chairs should be closely linked to transmissionelectron microscopy technique laboratories.• Creation of special fellowships for doctoral students(e. g. Scherzer fellowships) which should be made especiallyavailable to students from countries who do not haveadvanced instruments at their students’ disposal.References1. D.B. Williams, A.R. Pelton and R. Gronsky, Images of Materials, OxfordUniversity Press, New York - Oxford 1991.2. D.B. Williams and C.B. Carter, Transmission Electron Microscopy, PlenumPress New York 1996.3. Atomic Resolution Microscopy, National Science Foundation PanelReport (1995).4. M. Haider, S. Uhlemann, E. Schwan, H. Rose, B. Kabius and K. Urban, Nature392 (1998) 768.5. O.L. Krivanek, N. Dellby and A.R. Lupini, Ultramicroscopy 78 (1999) 1.6. L. Reimer (Ed.), Energy-Filtering Transmission Electron Microscopy, SpringerVerlag, Berlin - Heidelberg - New York 1995.7. M. Rühle, C. Elsässer, C. Scheu and W. Sigle, in: Proceedings of 2nd Conf.Int. Union Microbeam Analysis Societies, Kailua-Kona, Hawaii (2000) 1.8. G. Duscher, N.D. Browning and S.J. Pennycook, phys. stat. sol. (a) 166(1998) 327.

7.4. Surface Science and Scanning Probe MicroscopyD. A. Bonnell | University of Pennsylvania, Philadelphia, PA 19104, United StatesM. Rühle | Max-Planck-Institut für Metallforschung, 70174 Stuttgart, GermanyContributor:B. Baretzky (Max-Planck-Institut für Metallforschung,70174 Stuttgart, Germany).7.4.1. Introduction with General Remarks on SurfaceScience TechniquesThe investigation of material surfaces is an advanced areaof study in solid state science and materials science. Avariety of different imaging and diffraction techniques existthat allow the characterization of surfaces at the atomiclevel. The surface often serves as a platform to investigatefundamental aspects of materials science, such as crystalgrowth (e.g., epitaxy), chemical reactions (e.g., oxidationand corrosion), and catalysis. Surface science often acts asa “window” for investigating the microstructure of the bulkmaterial.A classical technique from the early days of materialsscience involves surface-level observation of glide stepsby replica techniques. From these surface-level studies,models for the plastic deformation of the materials couldbe developed.Instrumentation for the investigation of surfaces has becomestandard laboratory equipment. Optical microscopyand scanning electron microscopy (SEM) [1] are widelyused techniques. Significant advancements in SEM instrumentationallow the observation of surfaces under veryhigh-resolution in different gaseous environments of thespecimen. It is now standard practice to use instrumentswith a field-emission source and specific electron opticallenses. Chemical information obtained with SEM can beanalysed by energy-dispersive X-ray spectrometry (EDS)of the inelastically scattered electrons. The spatial resolutionof this technique depends on the pear-shaped excitationvolume of incoming electrons underneath the surface.For an electron energy of ~30 keV under SEM observation,the diameter of this excitation “pear” is about 1 µm. Areduction in electron energy reduces this diameter; however,the X-ray yield is also reduced. Furthermore, the electronenergy has to surpass the electron excitation energythreshold. Therefore, the excited volume of the specimencan only be modified in a very limited way by varying theenergy of the incoming electrons.Other surface-science techniques (see Table 7.7) includeX-ray photon spectroscopy (XPS), Auger electron spectroscopy(AES), electron probe microanalysis (EPMA),and secondary ion mass spectroscopy (SIMS). Instrumentationof these various techniques is highly developedand improved. A major task has been the quantificationof data, which also includes a correct description of errorbars and reliability. These various classical surfacescience techniques are useful when studying specificqualities and constraints. XPS is mainly used to get informationon the chemical state of atoms at the surface. Successfulefforts have been made to improve their ratherpoor lateral resolution; the depth resolution is a few atomiclayers. The strength of AES is its ability to measurechemical composition at the surface within a surfaceregion of about 10 nm in diameter. Efforts are also beingmade to extract information about the chemical state ofrelaxing atoms from the shape and position of the AESsignal. EPMA provides quite accurate quantitative localchemical composition (which also includes heavier elementswith high-order numbers). However, the informationstems from the pear-shaped volume of ~1 µm diameterunderneath the surface. SIMS allows the detection ofelements in a very small concentration, but the techniquesuffers mainly from an inaccurate quantification ofhigher concentrated elements.In summary, the following instrumental research projectsare currently under development: (1) reducing the information/responsevolume by increasing the spatial (lateralor vertical) resolution, (2) increasing the energy resolutionin order to detect even small signal shifts or fine structures,(3) and decreasing the detection limit by increasing thesignal-to-noise ratio. Furthermore, a layer-by-layer analysiswould be preferable for the study of thin-surface films.Today, “depth profiling” by an ion-sputtering removal ofsurface layers can be performed with high reliability andhigh-depth resolution on the order of a monolayer. Thistechnique, however, is limited by physical constraints [2].Integrating different surface science techniques describedabove into one instrument is a promising goal.Information on the relative orientations of crystalline grainsin a polycrystalline material can be retrieved by means ofelectron back scattering diffraction (EBSD). EBSD canbe used to investigate texture on very small scales [3].ADVANCED ANALYSIS OF MATERIALS253

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART254Requirements XPS AES EPMA/WDS SIMS SEM/EDSQuantification + o ++ — oDetection limit o o + ++ oEnergy Resolution/chemical shift ++ + o -Mass resolution ++Image resolution — ++ - + ++Lateral resolution — ++ — + -Vertical resolution ++ ++ — ++ —Depth profile + ++ - ++ —Table 7.7. Comparison of the different classical surface analysis techniquesfor determination of the chemical composition at the surfaceand in near surface regions (XPS: X-ray photoelectron Spectroscopy;AES: Auger electron spectroscopy, EPMA/WDS: Electron probe microanalysisusing WDS (wavelength dispersive spectrometer); SIMS:Secondary Ion Mass Spectrometry; SEM/EDS: Scanning electronmicroscopy using EDS (energy dispersive spectrometer)). The classificationis given depending on the possibility to fulfil the requirements:very good (++), good (+), medium (o), low (-) and very low (—).In situ measurements made by different instrumentsresult in dynamic studies of materials processes. Thoseinvestigations are extremely important for studying processesin catalysis, corrosion, and epitaxy.A classical domain of in situ experiments in analyticalelectron microscopy (AEM) covers investigations of intergranularsegregation on in situ intergranularly fracturedsurfaces, with one of the surface science instrumentsdescribed above. Fundamental insight into the embrittlementprocess could be gained by this technique [4].The classical techniques for the determination of surfacestructureand surface-reconstruction results are diffractionstudies of electrons of different energies: (1) lowenergyelectron diffraction (LEED), and (2) reflection ofhigh-energy electron diffraction (RHEED). The backscatteredelectrons are also being used to image surfaces(by LEEM and photo-emission induced electron microscopy,PEEM). The resolution of these images is on theorder of 1 µm. Correction elements (see Chapter 7.3) havebeen included, allowing for the correction of aberrations,which results in a better image resolution. The latter experimentsare now often being performed at high-brilliancesynchrotron sources (see Chapter 7.1), resulting in highintensitysignals for better imaging.All of the “classical” surface science studies discussed inthis chapter were first performed during the mid-twentiethcentury, resulting in mature, user-friendly instrumentation.The instruments operate in an ultra high vacuum(UHV) and are quite costly. Typically, existing service centresin Europe make all surface science techniques availablefor interested materials science “customers.” Materialsscience research would benefit from making theseEuropean centres linked and collaborative.Binnig, Rohrer, and Gerber [5] invented in 1982 the scanningtunnelling microscope (STM). This invention revolutionizedand advanced the fields of surface science. In thesame year they observed tunnelling through a controlledvacuum gap and imaged single atom steps. In 1983 silicon(111)-(7x7) reconstruction was imaged in real space forthe first time, marking the birth of a new field [6]. A decadelater, STM gained worldwide use.Shortly after the invention of the STM the atomic forcemicroscope (AFM) was in operation. With this instrumentalso non-conducting materials can be investigated. Othertechniques were developed when the probe (often anatomically sharp tip) is scanned over the surface of thematerial. Different interactions between tip (probe) andsurface can be utilized for the measurements of differentinteractions (mechanical, magnetic, electric) under differentatmospheres. All scanning techniques are subsumedunder the expression of scanning probe microscopy (SPM).The development of a specific scanning probe microscope(SPM) is essentially a method for making localizedmeasurements of any property for which a detectionscheme can be devised. Detection strategies are now availablefor probing first order, second order, and third orderresponse functions to interactions. Thus it is now possibleto detect, e.g. thermal gradients, magnetic forces, photonemission, photon absorption, piezoelectric strain, electrostriction,magnetostriction and optical reflection withlocalized probes. The remainder of this Chapter will dealwith SPM. This technique is having a major impact inmaterials science, specifically in nanotechnology.Scanning tunnelling microscopy, scanning probe microscopy,and atomic force microscopy, in general, have had adramatic impact in fields as diverse as materials science,semiconductor physics, biology, electrochemistry, tribology,biochemistry, surface thermodynamics, organic chemistry,catalysis, micromechanics, and medical implants.The reason for the nearly instantaneous acceptance ofSPM is that it provides three-dimensional real-space imagesof surfaces at high spatial resolution. Images are basedon different signals detecting the local interaction betweena small probe tip and the investigated surface. Dependingon the particular SPM, the image can represent physicalsurface topography, electronic structure, electric or magneticfields, or any other local property. SPM allows imagingat unprecedented levels of resolution in different materials,even organic tissues and large organic molecules,without damaging the samples. This is in contrast to othermicroscopy techniques, including SEM and transmissionelectron microscopy (TEM).

7.4.2. State of the ArtIn this section STM will be predominantly considered,similar results and rules can also be considered for otherSPM techniques.In the early stages of STM there was no clear understandingof the detailed mechanism underlying the contrastformation. Recent developments published in originalpublications or several textbooks reveal the principles ofelectron tunnelling between a real tip and a real surface.The theory is presently well developed and comparisonsbetween theoretical calculations and experimental observationsresult in reasonable agreement.A description of the state of the art is most likely obsoleteby the time a book or report is written. There are a numberof reasons for this. Experimental conditions are alwaysimproving. The capability to determine the atomistic structurecan be done quite easily online, using very simple andinexpensive equipment (compared to big diffraction andimaging microscopes). However, an understanding of thebasic principles of image formation by tunnelling processesas well as by atomic force interactions has recently beenrevealed [6,7]. Therefore, a discussion of the state of theart in light of these newly revealed principles is relevant.Data analysis of topography and spectroscopy imagesof which I-V curves for a fixed probe position can oftenbe determined and detected is rather straightforward.Comparisons of microscopy data to scanning tunnellingspectroscopy (STS) calculations showthat there is goodagreement between experiments and theory. Details ofthe spectroscopy are widely understood. This also includesthe electronic structure of the tip and tip-inducedbending of Fermi surfaces.Spectroscopy leads also to the investigation of inelastictunnelling spectroscopy of, for instance, energy barrierheights at interfaces. The unique ability of STM to probethe electronic structure of surfaces directly has openedanother dimension in our understanding of surfaces byallowing the study of electronic states at the surface onan atom-by-atom basis. STM directly correlates the geometricpositions of atoms with their resulting electronicstructure.STM investigations of surface structures and of structuralor compositional defects at surfaces opened a completelynew and unexpected dimension of materials science.While diffraction studies by LEED usually are obtainedfrom a large area, individual defects and defect agglomeratescan be investigated by STM at surfaces and thesestudies lead to an understanding of critical properties ofsurfaces and reactions at surfaces (Fig. 7.12).The STM technique is also applied to investigations ofcrystal growth. For instance, studies of the growth of metalson different conducting or non-conducting ceramicshave led to a much better understanding of nucleation andgrowth of metallic films on different substrates.The imaging of the electrostatic potential leads to an understandingof domains in electronic and magnetic materials.Although, the interpretation of the images is not easy, itgives deep insight into the magnetic and electronic structureof surfaces. Often also information with respect tograin boundaries in the crystals can be gained.abcFig. 7.12. (a) High-resolutionSTM image of an atomicallyflat terrace of the TiO 2 (110)surface obtained in constantcurrent mode (V bias = 1.67 V,I t = 0.6 nA), with a black-towhitescaling of 3 Å. The unitcell of the reconstruction isdisplayed.(b) A plane view of the proposedmodel for the reconstructedTiO 2 (110) surface.Large dark spheres representO-ions in the bridging oxygenrows, large gray spheres aredue to in-plane O-ions, andsmall black spheres representTi 4+ . The dimensions ofthe unit cell are a 1 = 8.85 Åand b 1 = 14.26 Å, and theangles are = 65.5° and = 114.5°.(c) Scanning tunnel spectrafrom the TiO 2 (110) surfaceacquired from bright anddark contrast regions inthe image. (Wagner et al.Appl. Phys. A 66 suppl. (1998)1165).An understanding of microelectronic devices requires theunderstanding of the physics of the carrier transportthrough thin films and across interfaces. These investigationshave been successfully performed by ballistic electronemission microscopy (BEEM). This STM techniquecomprises a family of spectroscopies that addresses thetransport and scattering of electrons and holes in multilayeredstructures. Successful results, especially withSTM surpass all experimental results obtained so far byother surface science techniques.ADVANCED ANALYSIS OF MATERIALS255

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART256AFM can be applied to the study of topography and interactionsbetween the tip and the surface of a conducting ornonconducting material. Enormous progress has beenmade for different structures, especially functional materialsfrom which information about electronic, electric,and magnetic properties can be obtained. Furthermore,AFM can also be applied to liquids and organic specimens,leading to an understanding of processes in a cell’s DNAon the nanometre scale.Furthermore, AFM techniques can be used for nanomechanicsinvestigations. For such studies, the tip of the AFMis used for two aspects: (1) the tip of the AFM is employedto produce indents in a specimen, and (2) friction measurementscan be done by scratching the tip over a surface.The mechanical forces are then measured with a specialattachment to the AFM. Information on the materials canbe obtained on a nanometre scale. The modification of thesurface by the test can then be made visible by imaging thesurface after the test in an imaging mode.7.4.3. Future PerspectivesIt is quite obvious that SPM techniques are instrumentalin the investigation of processes in the nanotechnologyworld. AFM is an adequate technique to investigate surfacetopography, small particles and modifications of thosethrough different treatments. However, an enormous impactcan be expected by combining the different measurementtechniques (e.g. magnetization or electrical forces)with properties sensitive to topography. One promisingtechnique includes also the combination of SPM and nearfield scanning optical microscopy (NSOM). With the lattertechnique the diffraction-limited resolution of opticalmicroscopes can be overcome. The combination of thedifferent techniques will definitely have an interestingimpact on high-resolution imaging of solid and soft surfacesof materials.The different SPM techniques can be applied to get informationon bulk materials by investigating defects close tosurfaces which are, of course, connected to the underlyingbulk. The application to soft materials will allow the successfulinvestigation of single molecules extending the fieldto nonperiodic materials.One exciting challenge for the improvement of SPM willbe the development of sensors than can produce valuablequantitative results. For example with the availability ofvery sensitive force transducers in the range of nN (e.g.mechanic, friction, magnetic or electric) forces can bemeasured and also applied to investigate the local responseof the materials. This will be a springboard for the understandingof fundamental phenomena like adhesion, surfacereactions, friction, tribology, wetting. The ability tomanipulate materials at the atomic scale will be an impetusfor next-generation research in the broad field of nanotechnology.1.2.3.4.5.6.7.ReferencesL. Reimer, Scanning Electron Microscopy, 2nd ed., Springer, Berlin,Heidelberg (1997).J.C. Vickerman (Ed. ), Surface Analysis – The Principle Techniques, J.Wiley & Sons, Chichester (1997).A.J. Schwartz, M. Kumar, B.L. Adams (Eds.), Electron BackscatterDiffraction in Materials Science, Kluwer Academic/Plenum Publ., NewYork, Boston, Dordrecht, London, Moscow (2000).W.C. Johnson and J.M. Blakely (Eds.), Interfacial Segregation, AmericanSociety for Metals, Metals Park, Ohio (1979).P.A. Dowben and A. Miller, Surface Segregation Phenomena, CRC Press,Boca Raton, FL (1990).G. Binnig, H. Rohrer, and C. Gerber, E. Weibel, Phys. Rev. Lett. 49 (1982)57.D.A. Bonnell, Scanning probe microscopy and spectroscopy : theory,techniques, and applications, 2nd ed., Wiley-VCH, New York (2000).S.N. Magonov, Surface analysis with STM and AFM : experimental andtheoretical aspects of image analysis, VCH, Weinheim (1996).The great advantage of all SPM techniques is the ability todo time-resolved investigations which give an insight intoatomic or near-atomic processes in all materials.

7.5. Three-Dimensional Atom ProbeG.D.W. Smith | University of Oxford, Oxford OX1 3PH, United KingdomM. Rühle | Max-Planck-Institut für Metallforschung, 70174 Stuttgart, Germany7.5.1. IntroductionAtom probe microscopy was first performed in 1951 by E.W.Müller at The Pennsylvania State University when heimaged individual atoms with a field ion microscope [1]. Hisvery impressive results show the structure of the surface of atip of tungsten where each bright spot corresponds to asingle atom. Since that time, enormous progress has beenmade in instrumentation, especially in signal detection andprocessing. The most recent advance is the 3-D atom probetechnique (3DAP), which is now firmly established.The 3DAP traces its origin back to the field electron microscope.However, a number of steps had to be accomplishedbefore the development of the 3DAP could occur. The atomprobe microscope is based on the principle that electronemission from a solid can occur in the presence of a strongelectric field. This technique was used to image surfaces;however, Müller introduced a new type of microscope inwhich the specimen was in the form of a sharp needle.Extremely high fields were applied, and with a large distancefrom the tip of the needle to a screen, high magnificationof the simple imaging system was achieved so that atomicresolution images of the tip could be obtained on the screen.The next step was the introduction of an atom probe as afield ion microscope. This allowed, by time-of-flight analysis,investigation of the specific atom or sample region witha mass spectrometer. The fluorescence screen, which madethe image visible, had a hole in its centre where the atomscoming from a selected region were analysed. The specimen(tip) could be adjusted by tilting the imaging screen.Next was the introduction of an imaging atom probe, whichmeant that the number of atoms analysed from the specimenhad to be increased by several orders of magnitude.This required the elimination of the channel blades andthe screen assembly that contained the probe aperture thatpermitted the single atom detection to be positionedcloser to the specimen. All atoms emitted from the specimenhad to be detected simultaneously.7.5.2. State of the ArtThe present state of the art was achieved by the introductionof the 3DAP, originally developed by Blavette et al. [2]and Miller et al. [3]. The 3DAP is a position-sensitiveatom probe that allows an atom-by-atom analysis at severaldifferent locations simultaneously over an entire screen.A fully operational system was first developed by Cerezoet al. [4]. The instrument features a single atom detectorbased on a pair of microchannel plates and a wedge andstrip, or back anode. The X and Y coordinates of the ions’impact on the detector are determined from the relativecharge measured on the free anodes in the wedge and stripdetector. Additional details of the position sensitive atomprobe can be found in the literature.Continuous stripping of the specimen (layer by layer) inan automated way allows the determination of the atomicdistribution of the different species through a thin cylindricalspecimen in the microscope. Individual atoms canbe detected and the atomic position can be determinedwith high accuracy.This instrument allows the analysis of cylindrical parts of aspecimen (with a diameter of about 30 nm and a length ofabout 200 nm), probing atom by atom through the specimen.The technique has enormous potential for the understandingof fundamental aspects of materials science, includingsegregation at grain boundaries, processes of nucleation inmaterials, radiation-induced defects, and decompositionof materials. Impressive results were also obtained on thethermal stability and interdiffusion in thin films.An example of the ultrafine-scale information availablewith the 3DAP technique is shown in Fig. 7.13, whichrepresents the atomic imaging of an -phase precipitateformed in an Al alloy. Segregation to the surface of the precipitatecan easily be recognized. The example illustratesthe detailed, ultrahigh-resolution chemical informationthat is available with an advanced 3DAP.Early 3DAP instruments suffered from a modest mass resolution.This was caused by the energy variations resultingwhen ions are accelerated during a voltage pulse. The problemwas solved by Cerezo et al. by incorporating a largeacceptance-anglereflection lens into the instrument. thisis presently the state of the art. The quantitative analysisof a specific stainless steel (see [4]) revealed e. g. the peaksof Ni, Cu and Mo can be clearly separated despite theseelements being present at levels of less than 0.1 % and, insome cases, separated by only one-sixth of a mass unit.ADVANCED ANALYSIS OF MATERIALS257

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART258Impressive results could also be obtained for the studies ofgrain boundary segregation, although the specimen preparationis tedious and time consuming. A 3DAP analysis ofgrain boundaries in an “interstitial-free” (IF) steel containing7 wt.% ppm of B revealed that B and C segregate at thegrain boundaries with a Gibbsian interfacial excess concentrationof 0.57 atoms/nm 2 . It is quite remarkable thatthe segregation of B is not confined to a single atomic layerbut is spread over a layer (parallel to the grain boundary) ofabout 1 nm thickness.Similarly, solid state reactions and intermixing in technologicallyimportant thin layer systems could be analysed bythe determination of the position and nature of individualatoms [5].Fig. 7.13. 3DAP elemental map showing a step at the interface of an Wphase precipitate formed in an Al-1.9 wt%Cu-0.3wt%Mg-0.2wt%Agalloy aged at 180 °C for 10 h. Segregation of Mg and Ag to the precipitateinterface is clearly observed, as is the enhancement of Cu in thevicinity of the step. (Courtesy H. Hono, National Research Institute forMetals, and Acta Materialia).7.5.3. Future AspectsWork on thin-film materials and devices will be further enhancedby current instrument developments to allow theuse of specimens in the form of microtips fabricated onthe surface of a planar substrate [5]. The basic principlebehind such instrumentation is the use of scanning probemicroscopy with the local electron atom probe. Microtipspecimens are fabricated from thin films or devices on aplanar substrate, either by masking and ion-beam millingor by the use of focussed ion beam (FIB) milling. Manyhundreds of microtips could be made within a few mm 2 ,all with the layers of interest at the apex. However,advanced instrumental developments are required for suchfabrication [5].Results from the 3DAP still fall short of full atomic resolution(with high spatial accuracy), due to the presence ofsmall trajectory aberrations that reduce the lateral resolution.The reason for this is poorly understood. Theoreticalwork has directed in several directions for the solution tothis problem. If those aberrations were understood and corrected,the 3DAP would be an ideal instrument for structuraland chemical analysis of real materials. Of course, acorrelation of calculated structures (by computer modelling)with experimental results would also be important.The leading research groups in the area of 3DAP are inEurope (Oxford, Gothenborg, Göttingen, Paris). To solvethese 3DAP resolution problems, it is essential that thesegroups form a closely linked network.Advanced 3DAP allows the measurement of individualatoms in the specimen volume, but also can detect smallamounts of doped or contaminant elements. This is crucialfor the understanding of their influence on desiredand sometimes not desired macroscopic properties, forexample, in microelectronic devices. With the availabilityof quantitative information on the number of atoms fromeach atom species and the place they occupy, it will becomepossible to reconstruct, for example, segregation ordiffusion profiles in order to determine the respective ratesand to understand via the “growth” laws the dominant processes.In principle, the separation of thermodynamiceffects from kinetic ones is now a realistic prospect.In the 21 st century, the combination of the 3DAP with TEMand atomistic modelling may provide a springboard for thesystematic development of the next generation of alloysand metallic multilayer devices. Atomic engineering ofthese materials is now a realistic prospect.Furthermore, the combination of scanning probe microscopy(SPM) and atom probe microscopy may allow detailedmanipulation of atoms. Individual atoms can be picked upby the SPM tip from a surface. The atom can then by analysedby atom probe microscopy. This technique may bethe key to overcome the current limitations of the 3DAPconcerning sample preparation, the restriction to conductingmaterials and to low sampling temperature.References1. E.W. Müller, Z. Phys. 131 (1951) 136.2. D. Blavette and A. Menand, MRS Bulletin 19 (1994) 21.3. M.K. Miller and G.D.W. Smith, MRS Bulletin 19 (1994) 27.4. A. Cerezo, T.J. Godfrey and G.D.W. Smith, Rev. Sci. Instrum. 59 (1998)862.5. A Cerezo, D.J. Larson, and G.D.W. Smith, MRS Bulletin 26 (2001) 102.

7.6. Laser SpectroscopyTh. Elsässer |7.6.1. IntroductionMax-Born-Institut, 12489 Berlin, GermanyUnderstanding the relationship between structure andfunction represents a central issue of basic materials research.Fundamental physical, chemical and/or biologicalproperties and functions of materials are determined bythe dynamics of elementary excitations in the ultrafast timedomain, i.e. between 1 fs (1 femtosecond = 10 -15 s) andapproximately 1 ps ( 1 picosecond = 10 -12 s). Such nonequilibriumand relaxation dynamics which are determined bymicroscopic interaction processes, can be observed in realtimeby optical techniques using femtosecond laser pulsesfor inducing and probing the linear or nonlinear materialresponse. Experiments with fs time resolution have provideda wealth of new information on transient electronicand vibrational properties of materials and on fast processeswhich are essential for realizing new functional properties[1].The comparably high peak intensities of ultrashort opticalpulses at moderate average power are essential for a quantitativecharacterization of the nonlinear optical propertiesof materials which are applied for optical frequency conversion,multiplexing and switching, processes underlyingmodern optoelectronic and all-optical information technology.With increasing data transmission and processingrates, optical information technology moves towards theultrahort time domain, requiring the implementation ofultrafast technology into communication systems. This isillustrated in Fig. 7.14 showing different optical technologiesand their characteristic time/frequency range.The rapidly increasing relevance of nanostructured materialsfor research and technology calls for new techniquesto optically address and analyze individual nanostructuresand to transmit information between them. This has ledto the development of new nanooptical techniques, in particularmicroscopies with sub-wavelength spatial resolution,which allow optical studies of single nanostructures[2]. The spatio-temporal dynamics of elementary excitationson a nanometre scale is accessible by combiningnanooptical and ultrafast techniques.7.6.2. State of the ArtIn this section, the state of the art of ultrafast materialscience and nanooptics is reviewed briefly and some futuretrends are outlined.(a) Pulse generation, shaping, and characterizationGeneration, shaping and characterization of fs pulsesprovide the basis for studying ultrafast processes anddeveloping ultrafast technologies. Present technology isFig. 7.14. Characteristic time and frequency scales of optical and electronictechnologies (upper part). In the lower part, the time rangescovered by ultrashort pulses, modulation technqiues and optical pulsecharacterization are given.ADVANCED ANALYSIS OF MATERIALS259Ultrashort Pulses, Optoelectronics and TelecommunicationsUltrafast Processes in Semiconductors:Coherent PolarizationsOptical Communication Technology:Time/wavelength division multiplexingCarrier DynamicsOptoelectronicsMicrowaveTechnologyDigital Electronics100 THz1 THz10 GHz100 MHz10 -14 s10 -12 s10 -10 s10 -8 sUltrashort optical pulsesOptical/optoelectronic modulation techniquesOptical pulse characterization

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART260mainly based on mode-locked solid state lasers andamplifiers which are combined with nonlinear opticaltechniques for frequency conversion and with pulse compressionmethods. The wavelength range from 100 nm inthe deep ultraviolet up to 300 µm in the far-infrared isnow covered continuously with pulse durations of lessthan 200 fs. In addition, soft X-ray pulses at wavelengthsbetween 5 and 100 nm and incoherent hard X-ray transientswith wavelengths below 1 nm are available. Theaverage output powers range from several µW up to about10 W, the corresponding peak intensities are betweenseveral 10 3 W/cm 2 and 10 15 W/cm 2 .Coherent pulse shaping techniques allow the generationof individual pulses or pulse sequences with tailored opticalphase characteristics and the compression of pulsesdown to about 2 fs duration. For a phase-resolved characterizationof pulses, methods like frequency-resolved opticalgating, spectral phase interferometry, and electroopticsampling are available. Highly sensitive techniques of nonlineartime-resolved spectroscopy are applied to monitorthe ultrafast time evolution of optical polarizations andnonequilibrium populations.(b) Ultrafast structural characterizationUltrafast techniques which are able to grasp transientstructures and nuclear motions in solids, liquids, and macromolecularsystems play an increasingly important rolefor understanding microscopic transformation processesand chemical properties of materials. Temporally and spectrallyresolved infrared methods are applied to monitor thecreation, disappearance and the mutual coupling of functionalgroups in molecules through their vibrational absorptionbands and to follow nuclear motions in real-time.Spectroscopic techniques of nuclear magnetic resonance(NMR) which works on substantially slower time scales,are being adapted for infrared spectroscopy in the picoandfemtosecond domain. First experiments have demonstratedthe potential of two-dimensional infrared spectroscopyfor structural characterization of biologically relevantmolecules [3]. Time resolved X-ray diffraction representsanother new, yet not fully implemented approach to studytransient species, e.g. during phase transitions in solids orsolid-liquid phase transitions [4].(c) Imaging, microscopy and nanoopticsUltrafast imaging methods, optical microscopy using femtosecondpulses, and nanooptical techniques providedirect information on the stationary and transient structureof materials. In optical coherence tomography (OCT),partly transparent biological materials, e.g. tissue, areirradiated with fs pulses and information on the spatialstructure of the layer investigated is extracted from thetime structure of the back-scattered light. This techniqueenables in situ imaging of the microstructure of materialsand has found medical application. In multi-photon microscopy,fs lasers serve as a light source for multiphoton excitationof organic chromophores embedded in the samples.Two-photon microscopy has developed into a standardtechnique of biomedical imaging.Imaging in the mid- and far-infrared (THz) range has becomea tool for studying the structure of porous materialand detecting specific material constituents, e.g. watertraces. Here, fs optical pulses serve for the generation andphase-resolved detection of electric field transients in theTHz range.Microscopy with subwavelength spatial resolution, i.e.confocal and near-field scanning optical microscopy(NSOM), is applied for optical characterization of structureson a length scale of typically 50 to 100 nm. Thoughthis spatial resolution is usually not sufficient to opticallyimage nanostructures, single nanostructures can beaddressed optically and local excitations can be created ata well-defined nanometre distance from a nanostructure.The electronic structure of individual semiconductor andmetal nanostructures and single macromolecules as wellas local disorder potentials in extended quantum structureslike semiconductor quantum wells have been studied,partly at cryogenic temperatures. While those experimentsprovide information on stationary properties, confocalmicroscopy and NSOM with femtosecond pulses can mapthe spatio-temporal dynamics of material excitations. Suchtime-resolved techniques have been implemented recentlyand first experiments on carrier transport in low-dimensionalsemiconductor nanostructures have been performed.Near-field techniques have also been used to write nanometrestructures onto materials.(d) Areas of applicationThe techniques outlined above have been applied in thefollowing areas of materials research:• Bulk and nanostructured semiconductors: Coherentpolarizations and their influence on the optical spectra,ultrafast redistribution and thermalization of nonequilibriumcarriers, and carrier cooling and trapping havebeen studied in great detail. A closed picture of the hierarchyof relaxation processes has been establishedby combining experimental and theoretical research.Detailed knowledge exists on microscopic quantumcoherence, Coulomb and phonon scattering, and onmanybody and nonlinear optical effects. Coherent allopticalcontrol has been demonstrated with excitonicpolarizations and photoinduced currents. This research

has led to semiconductor devices with completely newand/or strongly improved functional properties.• Metals, metallic nanoparticles, and correlated materialsincluding high-T c superconductors: Single-particle andcollective excitations of the carrier system, lifetimes ofimage states at surfaces and the related nonlinear opticalproperties including Faraday rotation and other magneticphenomena, are being studied in experiments withsub-10 fs time resolution. Correlated materials representa new field of research in which the investigation oflow-energy excitations, e.g. close to or below the superconductingenergy gaps, is particularly important, asthe electronic structure and optical spectra at higherphoton energies are not fully understood. In general, ourknowledge in this field is still much more limited thanfor semiconductors.Ultrashort pulsesPulse durations: 2 fs (2·10 -15 s) - 5 psWavelength range: 100 nm - 300 µm + soft/hard X-rayPeak power: up to 1020 W/cm 2• Control and quantitative analysis of optical phase(electric field).• Different measurement techniques for real-time probingof optical polarizations and nonlinear materialexcitations in the wavelength range indicated above.Time resolution up to about 5 fs.• Control of material excitations by interaction withtailored pulses and/or pulse sequences.• Nonthermal material processing with ultrashort pulses.Nanooptics – optics on a sub-wavelength length scaleADVANCED ANALYSIS OF MATERIALS261• Phase transitions of solids and material processing withfemtosecond pulses: Order-disorder phase transitions,e.g. melting, and optically induced changes of crystalstructure are being monitored via changes of the nonlinearoptical properties, e.g. through second harmonicgeneration at surfaces, and by detecting transientstructures by time-resolved X-ray diffraction. Materialprocessing and structuring with femtosecond pulsesfrequently occurs under nonthermal conditions andwith reduced thermal load on the material, leading toan improved quality of the processed samples.• Molecular systems in the liquid and solid phase, adsorbateson solid surfaces: The dynamics of electronic,vibronic and vibrational excitations as well as photochemicalreactions are the main research topics in thisfield which is frequently called “femtochemistry”. Aschemical reactions involve nuclear motions on a 10 toseveral 100 fs time scale, ultrafast techniques are anideal tool to follow the pathway of a reaction, identifytransition states and monitor the formation of products.There are first experiments in which the outcome of areaction has been manipulated by tailored pulses orpulse sequences, demonstrating the potential for opticalcontrol of chemical reactivity.During the last decade, the number of research groupsperforming basic research on ultrafast phenomena hasincreased substantially. In Europe, there are now approximately50 groups active in ultrafast material science, themain competitors being laboratories in the U.S. and – tosomewhat lesser extent – in Japan. European scientistshave introduced key innovations in ultrafast laser technologyand are among the top researchers in several areasof basic research, e.g. solid state physics or ultrafastNear-field scanning optical microscopy (NSOM):Spatial resolution > 20 nm (/20)Temperature range 5 - 300 KDetection sensitivity single photonsConfocal microscopy:Spatial resolution >250 nm (/2)Temperature range 5 - 300 K (resolution >500 nm)For both:Spectral resolution determined by laser source anddetection systemTime resolution determined by laser source (> 50 fs)Table 7.8. Summary of Experimental Techniques in Laser Spectroscopy.processes in soft matter. In Japan, a 10-years-programmeon “Femtosecond Technology” aims at a combination offundamental research with technological applications,mainly in telecommunications and ultrafast optoelectronics.Japanese groups play a leading role in optical telecommunicationswith ultrahigh data transmission rates. Incontrast to Japan and the U.S., the interest and involvementof European industry in ultrafast material science isstill very limited.7.6.3. Expectations and NeedsIn the following, some future trends of research in ultrafastoptics and nanooptics are outlined together with acrude estimate of the period after which major goals maybe achieved:

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART262• New femtosecond sources: Compact low-cost fs sourcespumped by semiconductor diode lasers and modelockedlasers working at high (GHz) repetition rates fortechnological applications (including telecommunications).Sources for ultrashort hard (keV) X-ray pulses atkHz repetition rate for time-resolved X-ray diffractionand absorption. Development of new laser materialsand components, e.g. high-power diode lasers for newpumping wavelengths. Phase shaping and nonlinearconversion of pulses in an extended wavelength range(2 to 5 years).• New and much more sensitive techniques for investigatingtransient structures and phase transitions by ultrafastinfrared and X-ray techniques represents a veryimportant direction of research which could leadto revolutionary new insight into the properties ofcondensed matter. Both laser-based methods and theuse of free electron lasers providing short hard X-raypulses will be important (5 to 10 years).• Optical coherence tomography with extremely shortpulses (improved depth resolution) and in extendedwavelength ranges (mapping of different constituents,2 to 5 years).References1. Ultrafast Phenomena XII, T. Elsaesser, M.M. Murnane, S. Mukamel, N.F.Scherer (Eds.), Springer Verlag, Berlin 2001.2. M.A. Paesler, P.J. Moyer: Near-Field Optics, Wiley, New York 19963. P. Hamm, R.M. Hochstrasser, in: Ultrafast Infrared and Raman Spectroscopy,M.D. Fayer (Ed.), Dekker, New York 2001, p. 273.4. A. Rousse, C. Rischel, and J.C. Gauthier: Femtosecond X-ray crystallography,Rev. Mod. Phys. 73 (2001)17.• Mid- and far-infrared near-field imaging with sub-100 nmspatial resolution, single pulse imaging (instead of scanningmethods). New local probe designs for sub-wavelengthoptical microscopy with improved spatial resolutionincluding single molecule probes, higher sensitivityand stability of local probe microscopies, multi-probemicroscopies (5 to 10 years).An interdisciplinary research environment is essential forcompetitive and successful research on and developmentof new optical techniques. This requires a long-term combinationof material science, engineering, physics, chemistryand biology in joint European projects and networks.Convergent beam electron diffraction (CBED) pattern of Si. Details of(220) diffraction disc near the [III] zone axis. Information can be gainedon the local bonding of atoms (ions) in the unit cell from the intensitydistribution.A rapid transfer of new techniques into materialsresearch requires a close cooperation of groups developingtechniques with those applying them as the feedback ofusers is necessary for optimizing new techniques.Support of dedicated competence centers which provideexperimental facilities for cooperative research and acceptguest scientists also for longer periods, is recommended,as ultrafast experiments require expensive equipment andhighly specialized knowledge and skills.

7.7. NMR SpectroscopyH.W. Spiess7.7.1. Introduction| Max-Planck-Institut für Polymerforschung, 55021 Mainz, GermanyPrecise knowledge of structure and dynamics of advancedmaterials is key to taylor them for specific functions. Asan example, such diverse technological challenges asefficient fuel cells, photonic sensors & devices or genedelivery systems all require transport of electronics, holes,protons or other ions. This transport critically depends onthe arrangement of the building blocks of the materialrelative to each other and their mobility on differentlength- and time scales. Even more informative for establishingstructure/function relationships is the directobservation of functional carriers themselves. Solid stateNMR spectroscopy has the potential of becoming one ofthe key methods to provide this vital information. In orderto achieve this goal, however, a large scale effort on aEuropean scale is required.7.7.2. State of the ArtNMR Spectroscopy is one of the most powerful techniquesfor structural investigations. Sofar most applicationsfocused on molecules dissolved in liquids, where NMR isan indispensable tool for the synthetic chemist, materialschemist or structural biologist alike. This was recognizedby awarding the 1991 Nobel prize in chemistry to RichardErnst, Zürich, for his eminent contributions to theadvancement of this technique. New materials for futuretechnologies, however, often function in the solid state,as highly viscous systems such as gels, or as moleculesattached to surfaces. Moreover, such materials typicallylack crystalline order in the traditional sense. Therefore,their structure cannot be determined with the requiredaccuracy by the most established methods for structuralelucidation, namely X-ray and neutron scattering. Here,solid state NMR provides the most promising approachFig.7.15. Recent advances combining fast magic anglespinning (MAS), two-dimensional double-quantum NMRADVANCED ANALYSIS OF MATERIALS263Intelligent Materials for Nanotechnology:Supramolecular ArchitecturesNetwork of Centres of ExcellenceCombination of MethodsCapital Investmentlack crystallinity,yet display hierarchical orderEUROPEAN ACTIONTechnique:Solid State NMRRESEARCHNEEDSMost promising toolfor providingstructural & dynamic informationand to establishstructure-function relationshipSTATUS10 mg samples:SyntheticMacromolecules& CeramicsFUTURE< 1mg samples:Hybrides:Synthetic/BiologicalOrganic/Inorganic17.6 T magnetic field (750 MHz)100-years Gedanken-experimenttime savingfor measurements25 T magnetic field (1.06 GHz)new detection schemesone-day experimentFig. 7.15. Summarized scheme: How solid state NMR is and will be capable of investigating materials from nanotechnology.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART264and high magnetic fields in excess of 16 Tesla (700 MHzor higher) have made it possible to– locate protons in hydrogen bonds, study their dynamics,and relate these findings, e.g. to thermal rearrangementsof smart supramolecular polymers (see Fig. 7.16a) orproton conductivity,– specify the mutual arrangements of aromatic moietiesand relate them to charge carrier mobilities in photonicmaterials (see Fig. 7.16b), as well as to molecular recognitionin guest-host systems,elucidate the organization of macromolecules attachedto surfaces, identify surface active sites and relate theseobservations to enzyme encapsulation as well as catalyticactivity of zeolites,– detect unexpected chain order of synthetic macromoleculesin amorphous melts & nanostructured materialsand relate it to their flow behavior,– probe the mechanism of generating inorganic / organichybrid materials, elucidate their structure on variouslength scales and relate it to their efficient ion conduction.As far as dynamic processes are concerned, multidimensionalsolid state NMR provides unique information aboutthe geometry, the time scale and memory effects of molecularor ionic motion over an exceptionally wide range oftime scales (Table 7.9). Combining solid state NMR techniqueswith concepts from magnetic resonance imaging,well-established in medical diagnosis, this information canbe spatially resolved and related, e.g. to the failure ofmaterials resulting from mechanical overload (shearbands). Solid state NMR is a highly competitive field, withstrong activities in the U.S. Most of our colleagues thereconcentrate, however, on biological systems and almostentirely focus on isotopically labelled samples, an approachnot well suited for materials applications. Notably, thegroup in the U.S., which currently uses the techniquesdeveloped in our laboratory most actively, works Europe,but in an industrial laboratory. Solid state NMR in Japan isconsiderably weaker than in the U.S. and sustained effortsare planned for the coming years.7.7.3. Expectations and NeedsaFig. 7.16 (a) The famous double-helix structure in DNA is based onhydrogen-bonded base pairs. The same principle for structureformation can be used in synthetic polymers, and the linking unitscan be investigated in detail by NMR, as shown here for the case ofa thermoreversible link. (b) The electric conductivity in molecularcolumns, which are candidates for “nano wires”, critically dependson the molecular stacking arrangement, which can quickly and indetail be elucidated by NMR spectra.These techniques require only small amounts of sample,typically 10 – 15 mg, and no special treatment such assingle crystals or isotopic labelling. Qualitative results aretypically provided overnight, thus the findings of the NMRinvestigations concerning supramolecular organizationcan directly be exploited by the synthetic chemist for optimizingstructures.bThe development of NMR methods is far from being complete.In fact, in the last decade convergence of the spectroscopicand technical demands on NMR spectrometersis observed. Typical solid concepts as magic angle spinningare now used in high-resolution NMR of liquids.Inverse detection resulting in significant signal enhancements,well-established in liquid state NMR will provideyet another boost to solid state NMR. We recently showedthat the sensitivity for such an important element as nitrogencan be increased by a factor of 10 through thisapproach. Another example is the detection of oxygen,which sofar has largely escaped elucidation by NMR. Evenhigher magnetic fields will become available, which willprovide improved spectral resolution and sensitivity. Thenext generation of high-field spectrometers in the range ofa Gigahertz (23,5 T) will be used with the same magnet forliquids and solids (Fig. 7.15). Major investments, however,are needed to build such a machine.These developments will enable NMR to handle considerablymore complex materials as it is possible today. Suchsystems will combine different interdependent functionalitieswhich can be triggered externally. Major advances,however, can only be achieved if the development of NMRis intimately intertwined with other techniques of materialscharacterization, in particular synchrotron radiationand neutron scattering, scanning probe microscopy, UVspectroscopyand last, but not least computer simulation.This is due to the fact that the structural information

ScatteringNMRDynamicsStructureTable 7.9. Comparison of scattering and NMR techniques as well asthe information provided about structure and dynamics of materials.incoherent coherent single quantum double quantumMolecular n-quasielastic 2D-, 3D-, 4DexchangesidebandsCollective n-spin-echo 2D-exchange decay of DQCMolecular WAXS, WANS sidebands 2D signal patternCollective pole figures, DECODER 2D signal pattern(packing) SAXS, SANS chemical shiftADVANCED ANALYSIS OF MATERIALS265provided by NMR is not as complete as a full three-dimensionalX-ray structure of a crystalline material. For instance,distance constraints provided by NMR will be most useful,if incorporated in the analysis of powder X-ray orneutron scattering data. If a series of compounds is to beoptimized, NMR can conveniently check whether relatedsystems exhibit the same or different local arrangementsof building blocks. Therefore, in such cases the muchlarger effort and cost of using large scale facilities such assynchrotrons or neutron sources can then be avoided.Likewise, computer simulation is indispensable in orderto make optimum use of the structural and dynamic informationprovided by NMR. Both, quantum mechanicalcalculations of NMR parameters probing the electronicstructure beyond a molecule, e.g. the chemical shift of protonsin proximity to aromatics or ions and moleculardynamics simulations are required. Major improvements,concerning the size of systems that can be handled are expectedduring the next 5 -10 years, due to the foreseeableincrease in computational power and development of moreefficient algorithms. Equally, surface NMR must be closelyintertwined with surface specific techniques such asscanning probe and electron microscopy, or synchrotronradiation. NMR, however, is the only technique availablewhich combines clear-cut chemical analytical informationwith probing the packing of molecules at surfaces7.7.4. Proposed Actions• A large scale programme advancing materials science inEurope must include a major commitment to NMR spectroscopy.The emphasis should not be on the developmentof new NMR techniques as such, but rather to foster interdisciplinaryresearch combining synthesis, characterization,computer simulation and the generation of devices.• Industry should be included in Co-ordination Groups,assuming rapid transfer of technical advances to industriallaboratories.Unique expertise in solid state NMR of Materials existsin Europe, e.g. in Switzerland (ETH, Zürich), France(Univ. of Lille), Netherlands (Leiden University), Poland(Poznan University), Germany (Mainz). Moreover, one ofthe world-leading manufacturers of NMR spectrometersis based in Europe (Germany, Switzerland, France).1.2.3.4.5.ReferencesK. Schmidt-Rohr, H. W. Spiess, Multidimensional Solid State NMR andPolymers, Academic Press: New York, 1994.D. M. Grant, R. K. Harris (eds.), Encyclopedia of Nuclear Magnetic Resonance,Vols. 1-8, Wiley: Chichester, 1996.P. Diehl, E. Fluck, H. Günter, E. Kosfeld, J. Seelig (eds.), NMR Basic Principlesand Progress, Vols. 30-33, Springer: Berlin, 1994.D. D. Traficante (ed.), Concepts in Magnetic Resonance, Vols. 7-13, Wiley:New York, 1995-2001.J. W. Emsley, J. Feeney, L. H. Sutcliffe (eds.), Progress in NMR Spectroscopy,Vols. 27-38, Elsevier: Amsterdam, 1995-2001.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART266Conclusions1. Current StateThe current state of modern analytical techniques inMaterials Science can be considered to be excellent inEurope, pioneering work has been done in the past in thedevelopment of X-ray and neutron scattering, in the developmentof quantitative electron microscopy, NMR andoptical spectroscopy. In summary, Europe holds a worldleadingposition in the advanced analysis of materials.2. Projects for the Near FutureIn the near future novel analytical techniques may emergewith large potential for Basic Materials Science:(a) New X-ray sources may become available in the nearfuture which are no longer based on Synchrotrons but onLinear Accelerators ("Linac-Based X-ray Sources”). Theywill provide X-rays with unheard properties, as the socalledX-ray laser (XFEL) which would give, for the firsttime, the Materials Scientist a fully coherent X-ray pulseat hand allowing time-resolved structural studies in thefemtosecond regime.(b) The proposed European Spallation Source (ESS) withits increased peak intensity will provide novel applicationsin Basic Materials Science, particularly in the fields ofpolymer science, magnetic materials and biological systems.(c) In high-resolution electron microscopy novel aberrationcorrection lenses (“C s -correction coils”) are now possiblewhich give acces to high spatial resolution at significantlylower electron energies. New concepts allow local electronspectroscopy with sub-eV and sub-Ångstrøm resolution.As a general trend, the classical boarders between diffraction,microscopy and spectroscopy dissappear: With theadvent of X-ray micro- and nanobeams local informationbecomes accessible to X-rays. Already today the strainstate of individual grains within a polycrystalline samplecan be isolated with the use of X-ray microbeams. TEMcan be combined with electron spectroscopy providingelement specificity. Shortest and fully coherent X-raylaser pulses would finally permit the materials scientist toobtain holographic images of materials on a femtosecondtime scale.3. Advanced Materials Analysis in Materials Science:It is somewhat interesting to note that today’s standardanalytical reservoir of a typical materials scientist encompassesonly a rather limited set of analytical techniques,as qualitative electron microscopy, powder diffraction,small angle scattering and EXAFS. NMR, X-ray and electronspectroscopy are also used, essentially as fingerprinttechniques. This is contrasted by novel dedicated andhighly specific analytical techniques which have beendeveloped in the past years and which could have an enormouspotential in basic materials science, but are notexploited today, because they are rather complicated andrequire an experimental and theoretical training prior to arobust application. Thus, one future challenge in basicmaterials science is the attraction of materials scientiststo Large Scale Facilities which offer sophisticated novelanalytical techniques for the investigation of their newmaterials and material systems. Materials scientists whouse these facilities could profit a lot and, as a by-product,can play the role of a catalysor in the (so far rather unsuccesful)attempt of these facilities to attract researchlaboratories involved in applied materials science andindustries to make extensive use of the experimentalpossibilies offered there.4. OutlookTodays materials science and technology is based on ourinsight into the atomic structure of materials allowing usto compose taylor-made nanosystems with novel properties.In future nanosized materials will continue to play akey role in almost all key technologies. It is somewhat impossibleto predict, how materials science and technologywill be in 50 years from now, however, as it appears today,it will presumably be based on our understanding and controlof the dynamic behaviour of nanomaterials on thefemtosecond time scale. This endeavour can only be successful,if new sophisticated techniques will be at handwhich allow the analytical access to this new domain ofbasic materials science.

5. Necessary Action – Advanced Materials Analysis(c) ResourcesIt is mandatory that Europe devotes strongest efforts tomaintain its leading position in the forefront developmentand advanced use of new analytical techniques. Thisknow-how is considered to be prerequisite for the understandingof new materials phenomena and for the developmentof new materials with novel properties. The followingEuropean actions are recommended:(a) European NetworksThe development and construction of new dedicatedinstrumentations for advanced materials analysis whichrequire larger investments (> 1 Mio Ecu) has to be supportedon a European level. Particular focus should in thedevelopment of innovative analytical techniques whichcarry the potential to unravel new time and length scalesand which are of interdisciplinary use. The Centres of Excellencelisted in (b) should coordinate such enterprisesand the later use of such new experimental stations by theEuropean materials science community.ADVANCED ANALYSIS OF MATERIALS1. Creation of interdisciplinary networks for the applicationof Synchrotron Radiation, Neutrons, Electron microsopy,NMR and Laser Spectroscopy in basic materialsresearch.2. Long-term support of those large scale installations inelectron microscopy, NMR and laser spectroscopywhich assure access for the European basic materialsscience community.3. Creation of Fellowships to foster crossdisciplinary programmesin advanced materials analysis.4. Creation of long-term "Local contacts for MaterialsCharacterization” at synchrotron and neutron scatteringfacilities, staffed with experienced personnel (scientists,engineers) as the primary contacts for materialsresearchers from the different institutions and differentresearch fields in Europe.(d) Training1. Creation of fellowships for doctoral students, postdoctoralstudents at large scale facilities.2. Creation of mobility programmes for young scientistsand for achieved experts to support flexible stays atlarge scale facilities.3. Support of European Workshops and Conferences in“Advanced Techniques in Materials Characterization”(e) European Advisory BoardsA European advisory board is strongly recommendedwhich coordinates the Synchrotron Radiation and NeutronActivities in Europe.267(b) European Centres of Excellenceshould be created in:1. Synchrotron radiation for basic research in materialsscience2. Neutrons for basic research in materials science3. TEM Analysis4. NMR Analysis5. Laser Spectroscopy (in particular ultrafast spectroscopy)6. Advanced analysis of surfaces, interfaces and nanomaterials7. Structure analysis of biomaterials(f) European Large Scale FacilitiesEuropean support is recommended for the new initiativesto build the new-generation facilities, in particular theEuropean Spallation Source (ESS) and the 1 Ångstrøm-X-ray-Laser (XFEL), which carry the potential for futurebreakthroughs in materials science.

CHAPTER 88. MATERIALS SCIENCEIN EUROPEH. Dosch and M.H. Van de Voorde | Max-Planck-Institut für Metallforschung, 70569 Stuttgart, Germany2682698.1. The Importance of MaterialsAll modern societies are experiencing a profoundchange in their social and economic structures. Astechnology marches forward, many traditional occupationsare disappearing, while the number of peopleworking in high-tech occupations is increasing. There isno doubt among politicians and their advisors that the economicallystrong societies of tomorrow will be based onknowledge and technological skills, particularly in regard to- energy and environment,- medicine and health care,- mobility and transportation,- information and communication.These have been recognized as the key technologies thatwill determine the future welfare of society. It has alsobeen realized that any progress in these technologies criticallydepends on the development of new and tailor-madematerials with improved or novel properties, e.g., newbiocompatible materials for medical applications, andopto-electronic materials for computers and communicationdevices. Pressure to improve and protect the environmentmeans that recycling issues will affect almost allfields in which new materials are produced.Modern high-tech materials are prerequisites for all majorresearch and development areas, from space programmes,astronomy, and particle physics, to modern surgery, computing,and fuel cell research. While all these technologiesrely on the precise and dependable performance ofspecialized materials, the role of materials science isoften not appreciated by the public because its activitiesgenerally take place in the background. For science tocontinue to develop materials for new technologies in thefuture, however, a greater appreciation of its importanceto economic growth and social prosperity is needed. Newmaterials and materials systems with improved performanceand previously unimagined properties are essentialif European industry is to remain competitive anda high standard of living is to be guaranteed for morepeople well into the 21 st century.From high school science we have learnt to associate agiven material with certain characteristic properties, suchas electrical conductivity, specific heat or melting temperature.As our ability to control the structure of materialshas now been extended to the nano-scale (around 10 -9m), however, we have come to realize that the behaviourof a material can be significantly different when confinedto extremely small sizes. These “nano-properties” aremostly due to the high surface-to-volume ratio of the particles,but they can also result from the limited extensionof the system, as many “bulk” properties are collectivephenomena averaged over relatively large length scales(typically µm or greater). Consequently, novel effects notseen in nature can be created by designing materials atthe nano-level. Nanostructures also test our theoreticalunderstanding of what happens when systems becomevery small, lying – as they do – at the border between classicaland quantum physics. Common examples of nano-▲Optical micrograph of a colour etched CuSn10 cast (G.Kiessler, MPI fürMetallforschung Stuttgart).

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART270designed systems are thin semiconductor and metal films,which exhibit unusual electrical and magnetic behaviour,and colloidal systems that are already in use today, e.g., titaniumdioxide (TiO 2 ) nano-particles in sunblock creams.More exotic structures and phenomena are now becomingthe focus of scientific interest, e.g., confinement ofliquids within nano-sized slits to understand how frictionand lubrication behave in the nanoworld.New theoretical concepts are needed to model thesestructures, and new analytical tools are required toobserve in situ the behaviour of atoms and molecules inconfined space. This is a very active research area for materialsscientists, and we can confidently predict that someof these phenomena will become the new technologies oftomorrow. Richard Feynman’s inspiring statement morethan four decades ago that “there is plenty of room at thebottom” is now being proved true. This new world of nanomaterialsis being made possible by continuous advancesin instrumentation and analysis, which allow us to buildmaterials atom by atom and will in future enable us toobserve molecular motion on femtosecond (10 -15 s) timescales.In the next decade the development of materials and discoveryof new phenomena will be strongly influenced byinterdisciplinary approaches involving numerous scientificand engineering fields, including condensed matterphysics, chemistry, biology, computer science, and materials,chemical and mechanical engineering. Successfulcollaborations between materials scientists and medicalscientists to create biomaterials, and between condensedmatter physicists and biologists to create soft condensedmatter (materials that are easily deformed by externalstresses, electromagnetic fields or heat), indicate thatsuch multidisciplinary research projects have a brightfuture.Another consequence of interdisciplinary research projectsis that future materials will become progressively“smarter”; in other words, the materials of tomorrow willactively communicate and respond with their environment.Packing materials will be able to sense the state ofthe contents, the superstructures of aeroplanes, trains,ships and cars will be able to detect microcracks and provideearly warning of any problems. “Smart coatings” willbe able to repair themselves if damaged or attacked bycorrosion. Computer chips will become as small as grainsof dust (“smart dust”). It is also envisaged that materialswill be created which self-organise to form large complexunits with controllable properties. Organic memory forthe computers of tomorrow may be built using specialpurposebacteria as “microbe-factories”. The possibilitiesare seemingly endless.Contributors:F. Aldinger (Max-Planck-Institut für Metallforschung,Stuttgart, Germany), W. Bonfield (Materials Science &Metallurgy Department, University of Cambridge, Cambridge,UK), P. Chavel (Lab. Ch. Fabry de l’Institutd’optique, Université de Paris-Sud, Paris, France), J. Etourneau(I.C.H.N.-UPR CNRS 9048, Université de BordeauxI, Pessac Cedex, France), C. Fisher (Japan Fine CeramicsCentre, Nagoya, Japan), R. Flükiger (Université de Genève,Genève, Switzerland), P. Hemery (Département SciencesChimiques, CNRS, Paris Cedex, France), J.-Cl. Lehmann(Saint-Gobain, La Défence Cedex, France), M. Marezio(Institute Maspec-CNR, Fontanini-Parma, Italy), C. Miravitlles(CSIS Instituto de Ciencia de Materiales, Bellaterra-Barcelona,Spain), E. Mittemeijer (Max-Planck-Institutfür Metallforschung, Stuttgart, Germany), W. Owens(UniStates, LLC, Medford, U.S.), M. Rühle (Max-Planck-Institut für Metallforschung, Stuttgart,Germany).8.2. The Role of Basic Materials ScienceOur skills in materials technology today are such that wecan control the properties of condensed matter at the atomiclevel. Today’s insights into the atomic structure of materialsand our understanding of the rules that control materialsbehaviour date back to the beginning of last century,when the laws of quantum mechanics were expoundedand when X-ray diffraction opened up to us the internalstructure of matter. The main motivation for these scientificachievements was scientific curiosity, and the humaninstinct to seek to understand the world around us.As a result of these fundamental discoveries in basicscience, new technologies were born, and a new type ofresearch emerged, applied research. Applied science,together with engineering, has been very successful inimproving and tailoring materials and phenomena for use

in real world applications. This evolutionary approachemployed by much of applied science leads to improvedperformance of materials and devices in a more-or-lesspredictable fashion. A textbook example is the continuousminiaturisation of integrated circuits (ICs) in accordancewith Moore’s Law, which states that the number of transistorson an IC will double approximately every 18months.Applied (i.e., evolutionary) materials science extendsscientific understanding through incremental and predictabledevelopments. Such applied technology is often theprovince of industrial research, which seeks to extend thecommercial capabilities of existing materials through lowercost, longer life, and more consistent and reliable products.On the other hand, it is also known that this evolutionaryapproach is fundamentally limited and cannot solvethe challenges in materials science that will confront usthe day after tomorrow. In order to tackle these problems,new, revolutionary approaches in basic science are needed.In this case, we should not aim for incremental improvementsin known materials and phenomena so muchas embark on a search for new materials and phenomena.Such research projects should in future be based at universitiesand materials science research institutes throughoutEurope, and initiate most of the curiosity-driven,pre-commercial materials research.Unfortunately, a feature of basic scientific research is thatits results are unpredictable, i.e., neither the success of aproject, nor the time required before positive results willbe forthcoming, can be forecast in a reliable way. In addition,it happens only rarely that a fundamental discoveryleads immediately to a new product. Rather it may takemany decades to produce “spin-offs” in the form of novelapplications and innovations. This fact lies behind why basicscience is often criticised or neglected; namely, thatmost of the announced “scientific breakthroughs” neverseem to become new, useful technology. This “conflict”between curiosity-driven science and the current needs ofsociety is as old as science itself. One need only recall thefamous encounter between Faraday and King William IV,who once asked the celebrated scientist what “his electricity”was actually good for. Faraday answered, “One day youwill tax it”.Curiosity-driven basic science has revolutionised manyold technologies and even sparked new ones in the past,e.g., the accidental discoveries of glass-ceramics with zerothermal expansion at Corning Labs, U.S., in 1952, andelectrically conducting polymers in the 1970s at the Universityof Tsukuba, Japan. In some cases, materials breakthroughshave a direct impact on current technologies,e.g., the discovery of the giant magnetoresistance (GMR)effect in 1986 by Grünberg at the Jülich Research Centrenow used in modern read head technology. In other cases,such as high temperature superconductivity (discoveredby Bednorz and Müller, also in 1986), unforeseen technicaldifficulties mean that more time is needed to turn theenormous potential of superconducting ceramics intoaffordable, reliable products. In the fifteen years that haveelapsed since the initial breakthrough, however, substantialprogress has been made, and we can expect to see thefirst useful applications of these amazing materials withinthe next few years.By its nature, basic research is best carried out at universitiesand national research laboratories, where commercialinterests can be set aside. Having said this, close contactwith industries that have an interest in the research,or are seeking solutions to materials problems, can benefitboth sides through the exchange of ideas and inspirationto innovate. Basic research at universities therefore hasthe dual role of increasing knowledge for the benefit ofindividuals and society, as well as helping solve problemsof industrial relevance and sowing the seeds for new technologies.The synergy between university-based and industry-basedresearch teams has been an important factor in the successof U.S. materials research, exemplified by the excellentlaboratories established by DuPont, IBM, AT&T,Corning and Exxon. These laboratories have produced severalNobel Prize winners, not least of all Bardeen, Shockleyand Brattain in 1956 for the discovery of the transistoreffect. This successful tradition has, unfortunately, neverbeen developed in Europe and has also now essentiallybeen abandoned in the U.S. Many European companieshave eliminated corporate or central research laboratoriesto more closely align research and development with immediatebusiness opportunities. Furthermore, there arestrong economic incentives to turn exploratory researchdirectly into new products. This commercialisation mayrequire researchers in industry to focus their efforts on resolvingmarket-related aspects of product/process developmentat the expense of fundamental materials understanding.The pitfalls and hazards of this rather nonsustainableapproach are manifold (e.g. in the form ofmaterials failure or undetected hazardous side-effects).Future breakthroughs in materials-based technologies canonly be achieved in Europe when the central role of basicscience in the search for revolutionary new materials andphenomena is recognised by the European Community. Itis critical that new and sustainable programmes in basicmaterials science research are launched to form a reliableMATERIALS SCIENCE IN EUROPE271

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART272Large/small Scale FacilitiesNational Research InstitutesResearchAdvanced Materials & PhenomenaDesign, SynthesisModellingCharacterizationEuropean CentresEuropean NetworksBasic Research in Materials ScienceEuropean Centresof ExcellenceBasic Research in Materials ScienceEuropean Materials Science BoardInterdisciplinarityPhysics, Chemistry, BiologyMobilityExchange ProgrammesSabbaticalsTrainingIndustryUniversitiesEuropeanWorkshops & ConferencesSummer SchoolsCoursesEuropean Long-TermResearch ProjectsEC-NSF-collaborationsHigh Risk Science ProgrammesPublic RelationsAdventure Basic ResearchPopular Science ProgrammesHigh School RelationsTeaching ProgrammesFig. 8.1. European scheme of basic research in materials science.backbone for European materials science networks andmaterials science centres. The schema proposed in Figure8.1 highlights the role of basic research in materials scienceand development in Europe (see also Sect. 8.6).The unquestionable triumph of materials science duringthe past century, which improved our lives immeasurably,may be ascribed to the successful search for elegant solutionsto complicated problems. This strategy must becontinued in the future and include new elements such asrapid information exchange and interdisciplinarity. Thenew millennium will see us enter an era of novel materialscomplexity. With new tools, new insights and understanding,and a developing convergence of the disciplines ofphysics, chemistry, materials science, biology and computing,we may dare to dream of novel and superior materialsproperties that were, until the 21 st Century, the stuffof science fiction.8.3. Social Acceptance of Basic ScienceToday we take for granted the fact that new high-tech productsappear on the market almost continuously. This hasled to the rather deceptive attitude that no effort need beput into research for the next generation of technologies,as they will appear from somewhere else in any case. Foryoung people it is even fashionable to be firmly againstmodern technology and new technological developments,while simultaneously relying on advanced telecommunications,transport and medicine for their daily lives. Thenatural sciences have steadily decreased in popularity allacross Europe, particularly among young people, who typicallyassociate physics with Chernobyl, radioactive wasteand nuclear weapons, chemistry with oil spills, pollutedair and poisoned rivers, and biology with mad-cow disease,gene-manipulated organisms and cloning.It is difficult to deny that basic science has lost much of itsprestige and trustworthiness in the public eye. This is due

in large part to the erosion of the traditional framework ofdisinterested, independent research at universities, andits replacement by a complex association of public, privateand industrial laboratories, often with commercial goals.Ordinary citizens are more likely to question the validity orusefulness of an innovation when vested interests are atstake, so that people are much more cynical about the roleof science as the final arbiter of truth than they were thirtyor forty years ago. At the same time, scientific breakthroughsare having a larger, more rapid and more profoundimpact on society than at any other time in history. Withoutscientific progress, Europe will be unable to competeeconomically or culturally with the rest of the world, andmany of the problems that we now face will grow in magnitudeuntil it is too late to fix them.One of the unfortunate consequences of these trends isthat many talented young students choose to study law,business or accounting rather than science. This dangerous“internal brain drain” has developed because scientistshave failed to communicate the relevance and risks oftheir research to the wider public in a convincing manner.It is also true that the priorities of science and the rest ofsociety have diverged over the last two decades. A profoundchange in society’s perception of basic science and its importancefor Europe’s future welfare is therefore requiredif opposition to scientific progress is to be reversed. It isimperative that materials scientists make every effort toconvince politicians and the younger generation that- the current prosperity results from scientific knowledgeobtained through intensive research over the last century,- tomorrow’s technology cannot be created by simplyextrapolating the current knowledge.- only through the application of science and rationalthinkingit is hoped to solve today’s problems in a satisfactoryway.It is the responsibility, and indeed duty, not only of materialsscientists, but also of all scientists, to restore the confidenceof the general public in our ability to create a betterfuture. Public understanding of science is important notonly so that scientists can discuss their research with laypeople (thereby, hopefully, receiving their support), butbecause without a better understanding and appreciationof science it will be impossible to maintain the culture ofinquiry and open-mindedness necessary for a knowledgebasedsociety. There is an urgent need for open dialoguebetween scientists and other groups in society, includingrepresentatives from national and European parliaments.Materials scientists must be more willing than has beenusual in the past to educate the public about the fascinatingadventure that they are involved in, and the manifoldbenefits that materials science brings to society. Sciencemust become embedded in a long-term political frameworkthat provides a sense of security and a positive visionfor the future.The first step in effecting a “sea-change” in sciencesocietyrelations is through better education. This willrequire better training of teachers in science for highschools, and include a larger science component in thetraining of elementary school teachers. It is also importantto provide better access to science education for maturestudents, perhaps through the Internet, or other “virtual”university schemes; the Open University in the UK is onesuch example. University science courses should also includehumanities components such as ethics, philosophyand history. This would help produce well-roundedscience graduates with improved communication skillsand an appreciation of the concerns and ways of thinkingof other members of society.Some other practical suggestions for improving the publicunderstanding of science include (see also Sect. 8.5 and8.6):- European Science Summer Events organised by EuropeanCentres for Materials Science in collaboration withhigh schools (see also Sect. 8.6). These could be alongthe same lines as the National Science Week activitiessponsored by the British Association in the UK,- high school curricula should be updated and modernisedto include the latest discoveries in science andtechnology. It is essential that the excitement and wonderof science be conveyed at an early an age as possible,- talented high school students could be offered internshipsin research laboratories during summer or wintervacations as part of their studies,- the training of science teachers should be updated to includethe latest knowledge, and bridging and refreshercourses offered to high school teachers,- closer ties between universities and high schools shouldbe established, perhaps by offering fellowships to talentedand motivated science teachers,- writing of popular books on materials science and itsfundamental importance to many technologies shouldbe sponsored, so as to give materials science a higherpublic profile.Possible initiatives to be taken and/or supported by theEuropean Commission include- popular science programmes on TV that focus on thelatest developments in solid state physics, chemistry andmaterials scienceMATERIALS SCIENCE IN EUROPE273

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART274- open days at research institutes with stimulating presentationsof current research and- popular science articles that focus on current challengesand achievements in basic research in materialsscience.Science and its application have numerous social, cultural,moral and philosophical dimensions that we need totake into account, whether as guides to our own actions orto better understand the actions of others. The public’strust in science cannot be re-established until scientistslearn to take into account value-laden world views (boththeir own and those of others) when discussing scientificissues. It is important that materials scientists be morewilling to engage the public in discussions and debate, notonly as “experts” with facts to convey, but also as individualswith opinions and concerns of their own who can workwith others to solve problems. More inclusive, less adversarialmeans of communicating with non-specialists needto be set in place to cope with the far greater diversity andpluralism of today’s postmodern society. Only by giving thepublic a say in which directions research heads, and theuses to which it is put, will science regain the confidenceof the broader public.Although materials science does not experience the samedegree of opposition as, for example, some of the biologicalsciences, there are still several issues of public concernthat materials scientists need to keep in mind, as recyclingissues or concerns regarding military use or misuse of materials(e.g. data protection) .Many of these issues also touch upon areas in the mining,minerals, construction, and manufacturing industries,which have close ties to materials science. In this era ofmounting environmental concern, it is therefore incumbentupon materials scientists to promote the use of environmentallybenign technology, e.g., non-polluting energysources, “cleaner” materials processing, and compositesmade from natural fibres. This is one area in which collaborationbetween scientists doing basic research and industriesseeking “greener” methods can reap huge rewards.Science has been well embedded in our culture and wayof life, but to ensure that this remains so, scientists mustlearn to listen more attentively and talk more transparentlyto the public. In this age of increasing globalisation,science must be seen to be of benefit to the underprivilegedand not just a means of profit for the privileged. Thisis especially true if it is to regain acceptance as a force forgood in the eyes of a large fraction of today’s society.8.4. The Interdisciplinarity ChallengeMaterials science has been very successful in the past, providingus with a variety of high-performance materials thathave laid the foundations for modern technology. Most ofthis progress has been accomplished by staying within wellestablished,somewhat isolated fields, such as semiconductortechnology, metallurgy or advanced ceramics.These days, materials science is more and more about developinga multidisciplinary approach to research in whichphysicists, chemists, biologists and engineers all contribute.Typical examples are surface science projects andnanotechnology, neither of which would be possible withoutcollaborative links between disciplines. We will increasinglyfind in the future biological molecules being incorporatedinto inorganic materials with tailored functions(for example, in sensor technology and in nano-motionresearch), and theoretical and analytical concepts frommaterials science being used in biology. While difficultiescan arise when scientists from different backgrounds tryto communicate (because of different terminology, concepts,aims, etc), the potential synergies of such interactionshave only partly been explored and their importancecannot be overestimated.Very often new and fruitful ideas come from young mindsnot yet set in the established, discipline-oriented way ofthinking, or when experienced scientists change from onefield to another. It is therefore important to encouragegreater exchange of students and scientists between disciplines.One way of achieving this is by ensuring that economicand administrative barriers do not prevent movementof scientists from one discipline or country to another.In Europe, this would be aided by standardisedqualification recognition procedures, European-wide trainingcourses, and official exchange programmes (see Sect.8.5). An interdisciplinary culture must also be implantedthrough educational (universities, research institutes) and

udgetary (funding agencies, national governments, EuropeanCommission) initiatives. It must also be realised thatthe heterogeneity of European culture is an asset with thepotential to provide imaginative ideas and diverse skillsthat must be more efficiently utilised in the future.High schools and universities tend to be rigidly structuredaround scientific disciplines, thereby rendering transferbetween disciplines difficult. This problem was realisedsome years ago by German physics departments, whichnow offer optional one-term courses in business and evenin art (so-called “soft skills”). This, however, does not dealwith the materials science issue addressed here. In orderto provide a more interdisciplinary education in the naturalsciences, it is tempting to replace physics, chemistryand biology courses at schools and universities with courseson “natural science” so as to convey a more unified, lessfragmentary, view of science. The danger is, of course, thatthis could easily result in graduates who understand alittle bit from everything but nothing in depth. Care musttherefore be taken to ensure that students are given theopportunity to specialise just at the right age or educationallevel where they have sufficient background knowledgeof all the sciences.One way of promoting a multidisciplinary approach tomaterials science is to offer students in different disciplines(physics, chemistry, biology, engineering) from all over Europethe chance to attend an intensive four-week trainingcourse in a field of advanced materials science (during theirsummer vacation, for example). These summer trainingcourses should end with an assessably written or oralexam. Students who successfully complete the coursecould be given a suitably named “diploma”, which wouldthen become a prestigious qualification that raises theemployability of students in the eyes of industry. In orderto ensure the success of this scheme, we recommendthe following measures to be taken by the European Commission:- use a rigorous procedure for selecting students,- solicit the best researchers in the field to run the courses,- hold courses at attractive locations that provide aninvigorating environment for study and- include plenty of free time for discussion and otheractivities, in a manner similar to the successful GordonResearch Conferences.Further strategies for fostering interdisciplinary scientificcommunication at all educational levels, from high schoolto university to postdoctoral training at research institutes,include:• establishment of university courses in interdisciplinaryareas, e.g., biomaterials courses offered by materials sciencedepartments in conjunction with biology departments,• modern student textbooks on aspects of interdisciplinaryresearch that should be written by acknowledgedexperts in materials science,• summer Schools for Interdisciplinary Science, whichshould be organised by European Centres of Excellence(see Section 8.6) for graduate and postgraduate studentsas well as selected high school students (based on academicexcellence or scientific aptitude),• European workshops and conference series focussingon the multidisciplinary aspects of materials science;these should be organised jointly by universities and EuropeanCentres for Materials Science and Technology(see Sect. 8.6) and be particularly open to students andscientists at the beginning of their careers.European funding agencies, national governments and theEuropean Commission should foster multidisciplinarystudies by• providing financial support for the European workshops,conferences and summer schools mentioned above,• supporting multidisciplinary materials science researchprogrammes,• supporting the establishment of interdisciplinaryresearch centres (IRCs) and facilities (see Sect. 8.6),• encouraging agreements between agencies that fundresearch in different disciplines to better coordinatemultidisciplinary research efforts,• granting fellowships and startup money to scientists takingtheir expertise from one field to another and• encouraging researchers in Europe to spend time in othercountries and laboratories, i.e., improve researchermobility (see Sect. 8.5.3).European centres for materials science and technology(see Sect. 8.6) should take a leading role in promoting interdisciplinarityby assembling diverse teams of researchersfrom materials science, physics, chemistry, biology, computerscience and engineering in order to tackle high profileand relevant scientific problems. This is the philosophybehind the IRCs established in the UK recently, suchMATERIALS SCIENCE IN EUROPE275

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART276as the IRC in Polymer Science and Technology at the Universityof Liverpool, and the IRC in Superconductivity atthe University of Cambridge.The enormous potential of the Internet (and its descendant,the Grid) for facilitating cooperation and communicationover large distances should also be exploited. Aregister of scientists and engineers working on materialsrelatedresearch could be established to provide easy,European-wide contact with experts in any given area ofmaterials science. e-Networks such as the MatNetproject being developed by the Federation of EuropeanMaterials Societies (FEMS) should be supported,expanded and emulated.8.5. New Schemes for Education, Research Careers andResearcher MobilityUp until less than thirty years ago, scientists working inthe fields of physics, chemistry and biology were highly regarded,and even esteemed, by the public at large. Onlytwenty years ago one of the chief career goals of high schoolstudents was to become a university professor in physics,mathematics or chemistry. This picture has changeddramatically over the last two decades as public fundingfor science has decreased and the implied “social contract”between scientists and the public has been questionedin the postmodern age (see Sect. 8.3). Today, the exactsciences have lost their lustre as the intellectual and innovativedeterminers of the future, many graduates turninginstead to “dotcom” companies and investment bankingbecause of the much more attractive salaries they offer. Inorder to reverse this dangerous trend, we need newschemes in education, a mechanism for promoting andupholding high ethical standards for scientists, attractivecareer opportunities for researchers and lowered barriersto researcher mobility within Europe.8.5.1. Science and EducationThe attractiveness of the pure sciences to the youngermembers of society, such as elementary school childrenand high school students, needs to be restored, since theywill be the future thinkers and opinion makers. We mustmake every effort to ensure that once again the best of themchoose careers in physics, mathematics, chemistry andengineering, rather than business and stock trading. Thisis a rather difficult task and requires action on many levels,by national governments, professional societies, institutesand individual scientists.It is also important to consider the curricula of elementaryand high schools, which tend to concentrate increasinglyon the liberal arts at the expense of the hard sciences. Whilethe importance of the humanities and social sciencesis undeniable, we need to devote an equal amount of timeto physics, chemistry and biology, as well as engineeringand computing, without extending the education periodfurther. In fact it has been suggested that, by optimisingclass content for both liberal arts and the natural sciences,the amount of time spent in school could actually be shortened.It is clear that teachers in primary and secondary schoolscannot tackle this task alone, but need assistance fromuniversities, research institutes and industry. Many scenariosare possible, limited only by the imagination of theorganisers. They range from- public evening lectures,- open days at research labs,- visits by young and motivated researchers to schools toconvey the excitement of science and a scientific career,- training seminars for teachers.At a European level such efforts can be complemented byvarious European science events, which should be open toall. Among the possible events that could be organised bythe European Materials Science Centres are• visits to large-scale research facilities,• summer schools on selected topics in materials science,• practical courses during the holiday periods at foreignresearch labs.

All these events should have a strong international dimension,i.e., many young people from different countriesshould be encouraged to participate and share theirthoughts and experiences. These European-wide excursionsshould be available first of all to those primary andsecondary schools within Europe that have already takenpart in some of the local science activities listed above.8.5.2. Careers in Materials Science and Basic ResearchPublic esteem for science and the attractiveness of ascientific career must be re-established. This will requireeffort from all sides, political, academic and industrial. Itis regrettable that many excellent materials scientistschoose to take jobs with lower qualification requirementsin order to secure a decent salary. If this continues,Europe will be forced to rely on scientists from outside theregion for its future welfare.In order to attract talented young people back to basicscience and research, fundamental changes in researchadministration and academic career structures are needed.Most jobs in academia can no longer compete with the careeropportunities currently offered by the private sectorand this situation will become even worse in the future if noaction is taken. It is evident that European universities andresearch laboratories need:- more flexibility in hiring people;- more competitive salaries;- more attractive career options for young people;- more women students and lecturers/professors.The establishment of new, prestigious awards at variouslevels (graduate, postgraduate and senior researcher) foroutstanding achievements in basic and applied research,sponsored by the EC, would also serve as an incentive formore people to take up careers in materials science. Thesecould be named after famous European scientists who laidthe foundations for modern materials science.The difficulty of obtaining university tenure and the longyears of waiting in low-paying, non-secure postdoctoralpositions beforehand often discourage students fromchoosing careers in academic science. Measures shouldtherefore be set in place that encourage universities torecruit more people to permanent positions, rather thanincreasing the number of postdocs. Part of this problemcould be relieved by an active campaign to attract morestudents (particularly female students) to materialsscience, thereby creating a need for more teachers.In addition, the versatility and intellectual preparednessof students must be increased without increasing the MScor PhD study time. Materials science graduates must continueto receive a comprehensive grounding in their fieldalong with quality research experience, but at the sametime career guidance should be provided to expose themto other fields of endeavour. To improve the employabilityof materials science graduates and postgraduates, increasedemphasis should be placed on developing thosequalities which industry is looking for in new recruits,namely problem-solving and communication skills,leadership potential, and the ability to work in multidisciplinaryteams. Students should also be imbued with a moreentrepeneurial spirit for commercialising and selling theirinnovations. These skills are useful not only for a career inindustry, but also for boosting the confidence of studentsin their ability to communicate with specialists and nonspecialistsalike. It is also important that students beencouraged to continually update and extend their skillsonce in the workforce through professional developmentprogrammes and personal study and/or training.8.5.3. Researcher MobilityScience cannot exist without the constant and directexchange of knowledge and ideas within the scientificcommunity. The publication of scientific results and theorganising of conferences and workshops are, thus, indispensableingredients for scientific productivity. Sciencehas become so complex that progress also requires scientificexchange on a broader level.A barrier to the efficient use of European scientific talentis the lack of mobility of scientists at all levels (from undergraduatesto university professors). Movement of undergraduatesand graduates within the EC is severely hinderedby the different education systems in each country.Language problems and cultural differences can also addto these difficulties.Increased mobility of junior and senior European researchersshould be seen as a priority for the EC to broadenscientists’ experiences, foster greater cross-fertilization ofideas and disseminate new findings and methods as rapidlyas possible. One way of promoting greater mobility withinEurope would be to establish a standard qualificationfor European Materials Scientists (EurMat) similar to theEuropean Physicist (EurPhys) qualification granted by theEuropean Physical Society. The EurMat qualificationcould be awarded by the Federation of European MaterialsSocieties (FEMS) on behalf of the EC and would beMATERIALS SCIENCE IN EUROPE277

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGARTrecognized throughout Europe as indicating a certain levelof academic attainment and professional experience hadbeen achieved by the bearer.Another way of improving researcher mobility would beby awarding European Studentships and Fellowships inMaterials Science to people at all levels of education andexperience (i.e., undergraduates, postgraduates, young andsenior researchers, research directors and university professors).It is important that the Studentships/Fellowshipsbe administered by only a few leading materials researchauthorities via a flexible, efficient and non-bureaucraticselection process based on ability and aptitude. Europeanresearch institutes should be encouraged to apply for EuropeanHost Fellowships that allow them to select talentedstudents and researchers for higher-level training and sabbaticalstays. The amount of the awards should be suitablyhigh in order to make them as prestigious and competitiveas possible. Means of encouraging greater researchermobility are discussed in more detail in the proceedings ofthe “Investing in Europe’s Human Research Potential” conferenceheld on Crete, Greece in October, 2000.2788.6. European Centres and Facilities for Materials Science8.6.1. European Facilities for Materials ScienceIn order to build up a modern European research infrastructurefor Basic Research in Materials Science, the existingEuropean research facilities have to become involvedand, if necessary, new facilities or research networks haveto be created. Fig.8.2. gives a more detailed presentationof a possible European infrastructure.(a) Large-scale facilitiesModern materials research requires access to radiationsources for probing atomic and electronic structures,which can only be generated by large, expensive equipmentlocated at central facilities. Several such facilitiesare currently in operation in Europe; e.g., X-ray and neutronfacilities are provided by the European SynchrotronRadiation Facility (ESRF) and Institut Laue-Langevin(ILL) in Grenoble, France, and ISIS at the Rutherford-Appleton Laboratory in Didcot, UK. To guarantee Europe’sleadership in materials science, several actions are necessary,including:• increased access to these facilities for materials scientistsfrom all over Europe;• establishment of new large-scale facilities.Large-scale research facilities can also serve as a focusfor the European materials science community, so that a“critical mass” of researchers can be gathered for makingbreakthroughs in new and challenging fields. Establishmentof large-scale facilities will also help make Europeanmaterials research more efficient by allowing researchersfrom different countries to work together, thereby reducingunnecessary duplication of research and exploiting thepotential synergy that comes about when researchers fromdifferent cultures and backgrounds interact. These facilitieswill also give researchers from smaller Member Statesthe chance to use large-scale equipment that they wouldnot otherwise have access to.These facilities should provide scientific services touniversities, research institutes and industry throughoutEurope, and have sufficient numbers of engineers andtechnicians to operate and develop them to their greatestpotential. In addition, access to these large-scale facilitiesshould be based on a flexible research proposal system.Competitive salaries and working conditions should beoffered to attract the world’s best scientists, and sufficientfunding (through government support or providing chargeableservices to industry) provided to ensure that the equipmentremains state-of-the-art. A European MaterialsScience Board (see Fig. 8.1. and Fig. 8.5.) should becreated to organize and oversee large-scale experiments,select the most promising and imaginative research proposals,and guide long-term planning/strategies in materialsresearch.(b) Small- and medium-scale facilitiesSmall- and medium-scale facilities are also necessary for avibrant research environment. These should be distributedthroughout Europe, including places geographicallyisolated from larger facilities, in order to maintain diversityand lessen the “brain drain” from the smaller Europeancountries to more favoured regions. They should also belocated or under the supervision of experienced researchmanagers who are acknowledged authorities in their field.

EC Materials ResearchInfrastructureResearchCentresResearch FacilitiesLarge-scaleSmall-scaleMedium-scaleVirtual(Networks)Centres of ExcellenceCentres of CompetencePhysical(Central Labs)MATERIALS SCIENCE IN EUROPEUniversitiesNational LabsIndustrial LabsMaterialsScienceMaterialsTechnology279Fig. 8.2. Schematic representation of the infrastructure necessary foradvanced materials research in Europe.Small-scale facilities should be devoted to a single area ofmaterials research, such as electron microscopy, surfaceanalysis (ESCA, Auger), scanning probe microscopy(STM, AFM, STS), crystal growth, optical characterizationor advanced materials synthesis and processing. Thesefacilities could be established from funds available fromthe EC, where the benefits of such facilities to EC projectsor networks can be demonstrated. Private industryshould also be encouraged to give grants or equipment forthe establishment of such facilities in order to promotefundamental research in the areas in which they are interested,and draw from the wider pool of expertise in academia.Such facilities can already be found in many universitiesthroughout Europe, but in some cases there is an urgentneed to replace or upgrade old and outdatedequipment.Medium-sized facilities established in conjunction withuniversities or at research institutes are ideally suited forinterdisciplinary research, for example, nanomaterials, biomaterials,advanced composites, and computer modelling.These facilities, and the centres that house them,should have a wider variety of equipment and techniquesavailable than the small-scale facilities. They should befunded both by private companies and government agencies,and should be available to all participating departmentsin the home university or institute, as well as sponsoringcompanies and researchers from other public researchcentres, preferably as part of a wider researchernetwork.8.6.2. European Centres of Competence in MaterialsScienceTo focus efforts on materials science in Europe and to gathera critical mass of researchers for making major breakthroughs,Materials Centres of Competence should beestablished in Europe. These should be Europe-wide andinterdisciplinary, and conduct cutting-edge research atundergraduate, doctoral and postdoctoral levels. Theyshould preferably be located near or at large- and mediumscaleresearch facilities or national institutes, or alternatively,exist as “virtual” centres formed from networks ofmaterials science laboratories around Europe (see Sect.8.6.4). Their mission should be to pursue world-classresearch into materials synthesis, characterisation, andprocessing in areas with great potential, including newapplications and technologies, and to coordinate researchin the public and private sectors.These EC-funded research centres, also referred to asCentres of Competence in Materials, should have a European-widemandate with the necessary status and supportto effect real change in the way materials research is conductedin Europe.Both regular “brick-and-mortar” centres and “virtual”centres should be created to satisfy the diverse needsof the materials science research community and provideoptimum benefits for Europe. These two types of organizationalstrategy can be summarised as:

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART2801. European research centres providing a geographicalfocal point for investment in infrastructure (large- andmedium-scale facilities) and for achieving a “criticalmass” of experts in the field of materials.2. Virtual research centres formed from a network of highlyspecialised research institutes and laboratories formedby connecting several catalysis groups from around theEC via a broadband communications network.The centres should be linked by the latest high-speed communicationstechnology, including data transmission andvideo conferencing, as part of an overall European-widecommunications network.Centres of competence should also be distinguished accordingto whether the main emphasis is on fundamentalor applied research:(a) European Centres for Materials ScienceThese centres should seek to perform fundamentalresearch into materials and provide a stimulating environmentfor physicists, chemists, biochemists and materialsscientists to work together. These centres should specialisein one or more of the research fields listed in Fig. 8.3,(i.e., newly established, interdisciplinary and innovativeresearch areas).These centres should collaborate closely with universities:- to establish high-quality research and training programmes,- to organise European workshops and conferences,- to investigate the potential of new materials and processesfor practical applications.(b) European Centres for Materials TechnologyThese centres should conduct interdisciplinary materialsresearch with emphasis on materials applications and supportscientific exchange and secondments with industry.The main research areas they should cover are listedin Fig. 8.4. These centres could also serve as “incubators”for venture companies exploiting advances in materialstechnology. Another important task would be to providetraining in entrepreneurial and management skills forscientists in conjunction with universities and businesses,including how to apply for patents and license technologyto other firms.The key to the success of the Centres of Competence inMaterials Technology will be close collaboration withindustrial partners:- to test and develop new materials applications,- to mediate the exchange of materials technology betweenuniversities and industry,- to nurture new businesses and spin-off companies basedon materials breakthroughs,- to organise workshops and technology fairs promotingnew materials technology.NanomaterialsSurfaces and InterfacesBio- and Soft MaterialsCatalysisMaterials for extreme EnvironmentsSuperconductivityMagnetic Materials & StructuresElectronic & Photonic MaterialsMaterials Theory & ModellingAdvanced Analytical TechniquesMaterials for Energy Production and StorageFig. 8.3. Suggested subjects to be covered by different European Centres or Materials Science.

Structural MaterialsNanomaterialsBio- and Soft MaterialsAdvanced Functional MaterialsComplex Composite ProcessingCoatings, Surface ModificationHybrid and Smart MaterialsMATERIALS SCIENCE IN EUROPEFig. 8.4. Suggested subjects to be covered by European Centres for Materials Technology.281Centres of Competence should offer fellowships to topclassapplicants from each sector (industry, academia andgovernment labs) to work on European materials projects.Permanent research staff drawn from all three sectors shouldalso participate in these projects, as well as support thewider range of tasks listed above. Materials Science and MaterialsTechnology centres should also maintain close linkswith each other so that the entire gambit of materials research,from fundamental studies to industrial applications,can be pursued in a coherent, forward-thinking manner.Collaborative projects could be managed in several differentways depending on the size and time-scale of the projectand number of participants. Two basic managementmodels could be:1. Public sector researchers to begin projects at universitiesor associated institutes, which are then moved tothe European Materials Science and Technology Centresand further developed with industrial scientists forapplication or sale to industry.2. Industrial researchers to work with public sector scientistsat materials research centres during all stages ofdevelopment, under the supervision of one of thecentre’s group leaders.Both types of research centres (Materials Science and MaterialsTechnology) should receive direct funding from theEuropean Commission, but public sector scientists shouldalso be allowed to perform research for private companieson a contractual, fee-paying basis. Intellectual propertyissues such as the right to publish results or maintain companysecrecy and so on would have to be clearly set outat the start of each project. These needs present no majorobstacle to such research being performed successfully.8.6.3. European Centres of Excellence (ECE)The title of “European Centre of Excellence” (ECE)should be awarded to a limited number of materialsscience institutes to distinguish them from the Centresof Competence in recognition of a sustained world-classlevel of performance. Strict and impartial selection criteriawould be needed that are based on scientific excellence,peer review and recognised achievement. These criteriashould be developed and agreed upon by the EuropeanMaterials Science Board. Candidate institutes shouldbe chosen from the Centres of Competence in MaterialsScience and Technology described in Sect. 8.6.2.European Centres of Excellence should be given increasedfunding to attract the best research staff and pursue largescaleresearch projects. The mandates of these centresshould be to perform materials research that will be ofbenefit to Europe and Europeans. The awarding of ECEscould by way of example be conducted every 5 years.(a) Selection and review procedureTo ensure that the title of ECE corresponds to the highestlevel of expertise in materials science, strict selection andreview criteria should be formulated by the EuropeanMaterials Science Board.(b) Role of ECEs in materials science in EuropeAs well as performing long-term, large-scale researchprojects at the forefront of materials science, Centres ofExcellence should also:- coordinate European Commission research programmesin materials science;- form a European Materials Science Board to advise on materialsresearch policies and guide their implementation;

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART282European Advisory Board“Education and Training”SelectionEvaluationof EducationandTrainingProgrammesTrainingEuropean Member StatesEuropean Materials Science BoardEuropean Advisory Board“European Centres of Excellence”SelectionEvaluation of ECE’sEuropean Centres of ExcellenceMaterials ScienceEuropean Materials Science ProgrammesEuropean Advisory Board”Large Scale Facilities”Adviceto ECResearchFig. 8.5. Proposed advisory scheme for European Centres of Excellence in Materials Science.- act as a think-tank in materials science to seek newresearch directions;- organise training programmes in conjunction with industry,providing qualifications recognised throughoutthe EC;- organise and sponsor public relation activities (newsreports, TV programmes, science fairs and Open Days).(c) Infrastructure of ECETo remain at the forefront of scientific excellence, ECEwill need:- Long-term support for the research programmes andmissions listed under b).- Top salaries to ensure competition for places and highquality applicants. Being awarded a position at an ECEshould be seen as a mark of distinction.- Installation of an efficient management office for EuropeanMaterials Science- An annual budget sufficient for maintaining and upgradingequipment and facilities.The proposed advisory scheme for ECEs is shown inFig. 8.5. ECEs should aim to be the best in the world intheir particular field, attracting the world’s best scientistsand fostering a culture of continuous innovation and opennessto new ideas. In their advisory role to governmentsand the EC, ECEs should seek the advancement ofmaterials science research for the benefit of Europeansociety.8.6.4. Virtual Research Centres (“European Networks”)Materials research has advanced to a point where it is oftenimpractical and sometimes impossible to assemble inone place all of the intellectual resources and specialisedequipment for a given research project. Progress in thisfield depends on establishing effective partnerships acrossdisciplines and among universities, research institutes andindustry. This networking enables cross-disciplinaryresearch, leveraging of resources with optimum use ofinfrastructure and facilities, and provides awareness of thelatest technology and potential industrial applications. Inaddition, it shares the risks and returns of long-termresearch and assembles teams that can emulate the fertileresearch environments of large research laboratories.The seeds of European networks lie in the active, but sometimessmall-scale, scientific networks that already existbetween universities, research institutes and industry. TheEuropean Commission should provide further incentives forthe formation of partnerships between groups with complementaryskills in appropriate subfields of materials science.The EC should make resources available through specialprogrammes that stimulate European networking. The ECThematic Networks and Marie Curie scholarships are excellentfirst initiatives and a good base for further development.An attractive alternative to establishing “brick-and-mortar”Centres of Competence is for the EC to fund “virtual”materials research centres in the form of networks of fourto ten pre-existing materials research labs and institutes.These could consist of groups from academia, public andprivate research institutes and industry.

8.7. New Strategies for European Research/Projects and Project ManagementThe success of several institutes in Europe with their manytechnological spin-offs over the past half century, stemsfrom their ability to:- integrate long-term and expensive fundamental researchprogrammes with training of postdocs and students,- establish multidisciplinary teams of experimentalistsand theoreticians,- keep in mind the possible applications that new discoveriescould engender.The development of the European Research Area (ERA)should seek to provide similarly favourable conditions forresearch to institutions throughout Europe, includingCentres of Competence in Materials Science and Technology.Management structures for large, long-termresearch projects should be set in place that are flexibleand non-hierarchical. Bureaucracy should be minimisedwith a simple application process for EC funds (at least forthe initial stages of proposal), and the money awarded as agrant, rather than on a contract basis, delegating responsibilityof how funds are spent on the principal institutesand researchers. The EC should pass on much of theadministration of the projects to national and local researchauthorities under the supervision of the European MaterialsScience Board.Several large scale, multidisciplinary projects will be needed,if Europe is to compete with the economic powerhousesof Japan and the U.S. in materials science andtechnology. Such projects should be organized as soon aspossible for the following priority research areas:- Nanomaterials- Surface science (incl. catalysis)- Smart materials- Biomaterials- Materials for alternative energy sources- Materials modellingTo ensure that long-term materials research is pursued in asustainable way, experts in basic science need to be includedin joint European Research Councils and their recommendationspassed on to industry, governments and thegeneral public. Major industrial companies have close linkswith national governments and the EC, and their views arewell represented. Similar lobbies for materials science inacademia, as a result of lack of organisation and a unifiedvoice, are less influential. In order to avoid short-term goalstaking priority over the long-term research projects neededfor fundamental breakthroughs, it is therefore importantfor scientists in the public sector, particularly those fromuniversities, to take on a more advisory role in nationalscience programmes and the EC Framework Programmes.A new long-term commitment to research in fundamentalscience is needed in Europe. Most fundamental researchprogrammes in new areas do not start producingcommercially useful results until after several years, soplans for basic research should extend beyond the fiveyearperiod of each Framework Programme to ensure thatinvestments of time, brainpower and taxpayers’money arenot wasted. As recognised by the research community inEurope, many of these highly interdisciplinary projectsare beyond the means of individual institutes, companiesor even some Member States. It is therefore strategicallyimportant for Europe to promote inter- and transdisciplinaryresearch in the manner described in Sect. 8.4 andelsewhere in this document.The new Materials Science and Technology Centresshould be given as much autonomy as possible, while stillmaintaining a transparent management structure andbeing subject to external assessments by acknowledgedexperts in the field. Fundamental research programmesshould not be managed by administrative bodies but byresearch team leaders who should retain financial accountabilityand be allowed to develop their own research styles.Researchers, technicians and engineers need to workclosely together to complete projects.MATERIALS SCIENCE IN EUROPE283

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART2848.8. Relations between Academia and IndustryA recent trend throughout Europe has been for the privatesector to take a much more active role in setting the researchpriorities and goals of university materials sciencedepartments. Today’s universities therefore often findthemselves pulled in many different, sometimes contradictory,directions. One of the hazards of commercialisingresearch at the university level is that the free flow of ideasand information can be hampered as scientists and financiersseek to protect their investments and gain advantagesover their competitors. There can also be serious conflictsof interest when researchers’ expectations of financialreward bias the interpretation, reporting or selectionof experimental results. There is therefore a pressing needto untangle universities’ relations with industry, and clarifyboth their roles in wealth creation.Allowing scientists at universities to pursue curiosity-drivenresearch free from commercial constraints is the onlyway to ensure a truly innovative research environment. Inthe long term private industry and the European economywill benefit from the new ideas and discoveries that will bemade. For example, many of the materials breakthroughsmade in U.S. industrial labs last century occurred whenscientists were given budgets and freedom to pursue theirown ideas, rather than following a fixed corporate strategicplan. The European Centres for Materials Science andTechnology proposed in Sect. 8.6 could fill some of thisneed by moving the commercialisation aspects of fundamentalresearch beyond the university environment, whilestill maintaining close ties between university labs, publicinstitutes and industrial labs.While outsourcing of basic research to universities by theprivate sector offers substantial benefits to both sides, it isalso important that industry be encouraged to establishand support their own in-house research labs. Withoutsufficient investment in its own basic research, the innovationsnecessary for the continued growth and competitivenessof a company are less likely to be forthcoming,as university departments cannot apply as concentratedan effort to a practical problem as the company itself can.The EC and individual governments should therefore takerapid steps to encourage businesses to invest more in research,both basic and applied, short-term and long-term,at universities and their own laboratories. Each countrythat does this is making a wise investment in its ownfuture.These suggestions are made with the aim of balancingindustrial research needs with the need for “blue skies” researchand teaching at universities to maintain the higheststandards of academic excellence. The issues are extremelycomplex, and a great deal more discussion needs to becarried out between all parties involved.8.9. International CollaborationEuropean Centres for Materials Science and Technology,along with other university departments, government andindustrial laboratories, should establish and maintainstrong links with non-European institutes where worldclassresearch is being performed, for example in NorthAmerica, Australia and the Far East. These links should bechosen judicially on the basis of similar research goalsand/or complementary skills/equipment. Competitionbetween different laboratories both within Europe andaround the globe can also motivate researchers to workharder and pursue innovative lines of thought.International exchanges via fellowship programmes withthe EC should be expanded. Exchanges and collaborativearrangements should also be encouraged with countriessuch as Russia, China, India and Mexico, with their largepool of talented, but under-resourced, scientists. To encouragemore researchers to spend time working in othercountries, greater support for language training and relocationcosts should be given, including help in finding jobsfor spouses and schools for children. International researchprojects in materials science should also be broadenedthrough collaboration agreements at the governmentlevel. These projects should be accompanied by improvedcommunications channels, e.g., video-conferencing capa-

ilities, and provide frequent opportunities for researchersfrom the different countries to meet and discuss theirresults, e.g., at conferences and workshops. Opportunitiesfor participating in international research projects shouldalso be more widely advertised and brought to the attentionof as many European researchers and laboratorydirectors as possible.Annex 1 – A European Network of Excellence in CatalysisR. Schlögl | Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, GermanyScience is an international activity that benefits from andeven depends on the sharing of ideas and techniques fromdiverse individuals, countries, and cultures. Major scientificbreakthroughs can only be achieved through internationalcollaboration.MATERIALS SCIENCE IN EUROPE285An efficient way to enable the European chemical industryto become more competitive on a global scale would bethe creation of a Network of Excellence in catalysis, knownas the European Virtual Institute for Catalysis (EVIC). Itssole task should be to generate a technology platform thatenables the chemical industry to better develop improvedand new processes. It should bridge the gap betweenknowledge-driven fundamental science and applicationdrivenR&D. Academic research develops methods of investigationand concepts of catalysis remote from practicalproblems and at a level of understanding which cannotsimply be extrapolated to practical catalysis. IndustrialR&D, on the other hand, operates on a more empiricalbasis and does not have the focus nor the resources to builda comprehensive theoretical framework.This Network of Excellence should bridge the gap betweenthese two streams of activities. It should operate at thehighest level of scientific excellence and seek to solve problemsfundamental to all industry and not just a specificcompany. The results from EVIC should enable individualcompanies either internally or with bilateral researchagreements with one partner from the network to developcompany-specific technology. EVIC should be interdisciplinarywith a structure similar to the general outlinesketched in Fig. A1. The network proposed here shouldwork on all types of heterogeneous, homogeneous and biologicalcatalysts.In order to remain independent of individual companyinterests EVIC should be financed completely from EuropeanCommission resources. A range of potentially inter-Critical TechnologiesIn situ functional characterizationEngineeringInnovative synthesisThe European Virtual InstituteforIndustrial Catalysis (EVIC)Technical preparationBiocatalysisKineticcharacterizationfor Chemical IndustryFig. A1. Outline of EVIC as an interdisciplinary technology platformenabling improved chemical process design.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART286ested beneficiaries is given in Fig. A2. Participation in thenetwork should be kept open to all parties interested atany time, even also after its foundation.CatalystmanufacturingCar industry for innovativetraction conceptsEnergyproductionProductionof chemicalsPlant and equipmentmanufactureCar Industry for environmentalprotectionother criteria. Europe has competent scientists in all areasshown in Fig. A5. However, substantial and reliable fundingis needed for collaborative research within a timetablesufficient for an in-depth research effort uninterrupted byfluctuations in short-term funding.EVIC should support medium- (6 years) to long-term(12 years) research into generic aspects of catalysis in thefields mentioned above. This research must be application-drivenand should not be curiosity-driven. Studiesaiming at fundamental understanding of complex technicalprocesses using validated models under relevant conditionsshould be part of the research profile of EVIC.Experimental studies on model catalysts under remoteoperation conditions and purely synthetic projects are tooacademic and should not be part of the activities of theCentre. Development of rational synthesis protocols forFig. A2. Industrial sectors that could benefit from EVIC. The fundamentaland strategic character of catalysis becomes clear from the rangeof businesses concerned.The research projects should be decided by the industrialpartners to ensure that all activities are applicationfocussed. Project leaders should be established scientistsin order to ensure the highest scientific standards. Thisarrangement is only possible with a virtual structure thatallows leaders to remain in their normal working environment.A number of administrative and coordinating officersworking full-time will be needed to support the projectleaders. Fig. A3 illustrates the organisation of such anetwork. A small nucleus of full-time staff supports thepart-time researchers and project leaders by coordinatingproject operation with multi-national consortia.ProjectleadersProjectpartnersDepartmentHeadsEVIC will require independent funding and a time schedulesuitable for the problem. Four periods of three yearsshould be suitable for most long-term projects, with initialand four intermediate international audits. The auditingcommission should be led by the beneficiaries (see Fig.A2) supported by academic experts from around the world.In this way the network can be run independently of shorttermeconomic constraints and is guaranteed not to loseits focus on the pre-commercial R&D.The network should have six departments and be led by acouncil of the six departmental heads. The six departmentsproposed are shown in Fig. A4.EVIC should bring together the best European researchersfor a given task. Participation should be granted strictlyupon scientific excellence in the required field and on noFig. A3. Schematic representation of the organization of a network ofexcellence.existing catalysts and search strategies to identify novelmaterials for catalytic applications (combinatorial chemistry)including the development of supporting technologiesmay, however, be a task of EVIC. The broader applicationand methodical developments of in situ characterizationwith the aims of integrating large-scale facilities(synchrotrons, neutron sources) and also providing celldesigns and attachments to commercial laboratory instrumentationshould be another task. The development oftheoretical concepts at the ab initio level as well as thebroadening of microkinetic analysis as research tools maybe further tasks.

MPI CoalResearchMPI MetalsResearchEngineeringTheoryMPI ComplexTechnical SystemsFritz-HaberInstituteBM SectionMPI Solid StateSciencesFig. A4. Centres of competence within the Max Planck Society thatcould contribute to EVIC. Their long-term commitment would makethem ideal as integrators for other activities being pursued in Europe.KineticsEVICMaterialsFig. A5. Strong interaction between the departments is necessary toensure that the most is made of the interdisciplinary nature of EVIC ifinnovative catalysis research is to be performed.MATERIALS SCIENCE IN EUROPEParticular emphasis should be placed on the broader applicationof biotechnology in catalysis. The discrepancybetween the potential of this technology and its representationin current industrial practice is striking and may becaused by a lack of proof of operability and of economicfeasibility in other than highly specialized drug synthesisprocesses. Development efforts and piloting processes,as well as solutions to problems concerning the compatibilityof biological catalysts with conventional chemicalenvironments, may be special process-specific goals.The output of all projects should be continuously monitoredby auditing assessments and reports to industrialworking parties about the activities of EVIC’s six departments.The projects should be selected via a bottom-upprocess with participation of industrial partners whoprovide guidance and are willing to test the results of theprojects within their own research but without activefinancial contributions. Intellectual property rights shouldbe guaranteed to the industrial partners while also protectingthe rights of the academic partners.EVIC’s finances should be sufficient to cover all costs oftravel for researchers, as well as consumables and largescaleequipment. It is important that all projects be conductedwith optimum efficiency, in other words, EVICshould maintain state-of-the-art apparatus and instrumentation.The bulk of EVIC’s finances should come fromcontributions from the consortium members. Standardcatalytic infrastructure and leading/support personnelshould be brought into each project by the participatingcompanies.287Each of the six areas of activity mentioned above shouldbe conducted by groups of several consortium members.A nucleus of institutions committed long-term to EVICshould seek to persuade existing projects in Europe (e.g.,national virtual catalysis projects) to coordinate theiractivities with those of EVIC. For example, Fig. A4 showsthe different partners of the Max Planck Society whichhave interest or skills in catalysis technology.Internationally known virtual centres such as NIOK inthe Netherlands, CONNECAT in Germany, or institutionalcentres like in Strasbourg (ECPM) and Lyon (IFP)and the British Leverhulme Centre for Innovative Catalysis,should contribute to the nucleus of institutions supportingEVIC.

CHAPTER 99. MATERIALS SCIENCE AND BASICRESEARCH IN EUROPE: CONCLUSIONSAND RECOMMENDATIONSH. Dosch and M.H. Van de Voorde | Max-Planck-Institut für Metallforschung, 70569 Stuttgart, Germany288289This White Book reflects the vision of a diverse groupof leading scientists in Europe concerning the futureof materials science. Experts in the field are convincedthat high-performance materials are the basisfor all key technologies and, thus, the future of every modernsociety. There is also common agreement that the challengesconcerning the increased complexity of high-techmaterials and greater world-wide competition can only bemet by well-organized, joint European Commission (EC)research programmes in basic materials science that ensuresustained financial support and the highest level ofexpertise. A number of recommendations for the EuropeanCommission authorities currently preparing the nextFramework Programme have been formulated with thesole purpose of making this vision a reality. These recommendationsare:• Materials research in the EC should be given the samepriority as biotechnology and informatics. Materialsscience plays a crucial role in the development and competitivenessof these and many other technologies,especially in the transport, chemical, energy, electronics,and aeronautical industries.• The EC budget for basic science needs to be increasedto a level comparable with that of Japan in order to remaincompetitive in the 21 st Century, in particular withthe Pacific region.• European materials research programmes have to becoordinated to avoid unnecessary duplication betweenresearch groups in different Member States, to promote efficientuse of resources, and to look for possible synergies.• The basic research, development and evaluation ofmaterials should fall under the jurisdiction of a Europeanmaterials science agency, modelled on the NationalScience Foundation (NSF) in the U.S. or the SwissScience Agency, with the minimum amount of bureaucracy.• The EC materials programme should span materialsresearch and materials technology, with emphasis onlong-term fundamental research.• The fragmented nature of materials research in Europeneeds to be replaced with a more efficient organizationalstructure. This could be achieved by establishing Centresof Excellence in Materials Science and Technologyto coordinate European-wide research efforts.• The number of interdisciplinary projects and educationprogrammes has to be increased and greater interdisciplinarynetworking actively promoted in Europe.• The EC should investigate plans for ensuring greaterresearcher mobility to make the most of Europe’s diverseskill base and cultural heterogeneity for spawning newideas. This should include the creation of a professionalqualification for materials scientists and engineers (Eur-Mat) that is recognized throughout Europe.• The EC should commence dialogue with non-scientistsand other interest groups to find ways of countering thedecreasing popularity of science in society. Steps shouldbe taken to increase the profile of materials sciencethrough better education, science fairs, institute opendays, summer schools, etc.• Greater numbers of students enrolling in materialsscience and related courses at university are needed.This may be achieved by promoting greater awarenessof the range of careers available, and also increasingsalaries of academics working in these fields.▲Transmission light micrograph of a shell obtained with polarizedillumination (U. Täffner, MPI für Metallforschung Stuttgart).

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART290Priority research areas for European materials researchshould be:Materials discovery and designTo accelerate the design and exploration of new materialsand novel phenomena and properties, priority should be givento the study of improved synthesis and processing, materialstheory/modelling and advanced analytical techniques.Interdisciplinary research strategiesCompletely new materials architectures and propertiescan be expected from the interplay between different typesof materials systems, in particular from the design ofdevices made from inorganic and organic materials on thenano-scale. Interdisciplinary research between physicists,chemists and biologists should be supported and coordinatedon a European level.Special materials with high innovation potentialSmart materials, biomaterials and nanomaterials will beamong the fastest growing areas of materials science overthe next few decades, as will be materials for alternativeenergy sources, including high temperature and magneticmaterials. Priority should also be given to materials thatimprove our management of the environment, naturalresources and recycling. Such areas should become animportant part of the EC’s long term research plans andsuitable funding should be made available to ensureEurope leads the way in each of them.This White Book should be regularly updated to serve asa source of ideas for policy makers, and academic andindustrial research directors. In the following sections, keyaspects regarding the future of materials science, includingtechnological trends and research priorities, are summarizedand recommendations made. With a concertedeffort from all European researchers, institutes andgovernments, Europe can succeed at the forefront ofmaterials technology and enhance both her economicperformance and the standards of living of her citizens.Contributors:F. Aldinger (Max-Planck-Institut für Metallforschung, Stuttgart,Germany), J.-F. Baumard (ENSCI, Limoges, France), G. Beck(Ecole des Mines-LSG2M, Institut National Polytechnique deLorraine, Nancy France), H. Bolt (Max-Planck-Institut für Plasmaphysik,Garching bei München, Germany), G. Davies (Facultyof Engineering, University of Birmingham, Birmingham, UK),J. Etourneau (Faculté des Sciences, Université Bordeaux I,Pessac Cedex, France), C. Fisher (Japan Fine Ceramics Centre,Nagoya, Japan), R. Flükiger (Faculté des Sciences, Université deGenève, Genève, Switzerland), H. Gao (Max-Planck-Institut fürMetallforschung, Stuttgart, Germany), U. Gösele (Max-Planck-Institut für Mikrostrukturphysik, Halle/Saale, Germany), P. Greil(Lehrstuhl für Werkstoffwissenschaften, Universität Erlangen-Nürnberg, Erlangen, Germany), N. Hadjichristidis (Departmentof Chemistry, University of Athens, Athens, Greece), P. Hemery(Département des Sciences Chimiques, CNRS, Paris-Cedex,France), H. Kronmüller (Max-Planck-Institut für Metallforschung,Stuttgart, Germany), R. Lipowsky (Max-Planck-Institutfür Kolloid- und Grenzflächenforschung, Golm bei Potsdam,Germany), P. Lutz (Institut Charles Sadron-UPR 022, CNRS,Strasbourg Cedex, France), J. Maier (Max-Planck-Institut fürFestkörperforschung, Stuttgart, Germany), E. Mittemeijer (Max-Planck-Institut für Metallforschung, Stuttgart, Germany),A. Mortensen (Department of Materials Science, Swiss FederalInstitute of Technology, Lausanne, Switzerland), N. Nakabayashi(Institute of Biomaterials & Bioengineering, Tokyo Medical andDental University, Tokyo, Japan), L. Nicolais (Dip. di Ingegneriadie Materialie e della Produzione, Universita ‘Federico II’, Napoli,Italy), W. Owens (UniStates, LLC, Medford, U.S.), P.S.Peercy (The College of Engineering, University of Wisconsin,Madison, Wisconsin, U.S.), K. Ploog (Paul-Drude-Institut fürFestkörperelektronik, Berlin, Germany), D. Raabe (Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany), M. Rühle(Max-Planck-Institut für Metallforschung, Stuttgart, Germany),F. Schüth (Max-Planck-Institut für Kohlenforschung, Mühlheima.d. Ruhr, Germany), Th. Wagner (Max-Planck-Institut fürMetallforschung, Stuttgart, Germany), D. Williams (Departmentof Clinical Engineering, University of Liverpool, Liverpool,UK).

9.1. Materials Phenomena and Techniques9.1.1. Materials Phenomena and PropertiesUnderstanding, control and tailoring materials phenomenaand properties on a microscopic level are key targets inmaterials science. By doing so we can develop new materialsto meet technological needs, and optimize materialsuse to reduce wastage and pollution.In the past, the primary task of materials scientists was toquantitatively characterize phenomena and develop moderntheories to explain them. Today we have accumulateddetailed knowledge of a large number of different electric,magnetic, optical, mechanical, and thermal phenomenadescribed in terms of classical or quantum correlations incondensed matter (Fig. 9.1). Materials science beyond theyear 2050 will be characterized by the control of materialsphenomena on the nanometre length and femtosecondtime scales. Several major targets exist for future analyticaltechniques, such as:Microstructural design: The further improvement of ourunderstanding and control of mechanical, thermal andchemical properties of multicomponent alloys, compositematerials, materials with nano-sized components, andceramics is needed in various key technologies. A majorchallenge here is the multiscale nature of many phenomena,which requires detailed understanding of how structuresat different length scales interact and influence eachother over different time scales. This will require considerableeffort on various fronts, including modelling andmicroscopic analysis.The tailoring of phenomena in a controlled and reproducibleway using nanotechnological concepts: Since mostmaterials phenomena are of a cooperative nature, they dependstrongly upon the size of the system and are effectedby the presence of surfaces and interfaces. This will allowtomorrow’s materials scientists to modify, for example, theelectric and magnetic response of artificial structures tothe precise values desired. Materials science is an extremelydiverse and multidisciplinary field that covers a widerange of novel phenomena, often with the potential forimmediate applications.Small-scale phenomena: The small-scale regime offersreal opportunities for developing sustainable and environmentallyfriendly materials that meet tomorrow’s technologicalneeds. Colloidal systems and biomimetic strategiesare two examples of an array of new concepts that willallow us to design small-scale systems with greater multifunctionality.The size dependence of properties such ashardness and superplasticity will give rise to new mechanicalphenomena (“smaller is tougher”) and new thermodynamicbehaviour that will have enormous impact onfuture technologies.Dynamic response of systems over very short time scales:Understanding and (in future) controlling ultra-fast processesin materials is currently of great scientific and technologicalinterest. It has recently become possible to probedynamical phenomena in materials on ultra-short timescales down to sub-picoseconds (see Sect. 9.4). The studyof ultra-fast structural relaxation phenomena will improveour understanding of phase transformations and structureformation. Rapid switching of magnetic domains in artificialstructures will be used in tomorrow’s informationtechnology. These are just two examples of this importantemerging field. Strong input and guidance from materialsanalysis and materials modelling will also be indispensable.The study of phenomena under extreme conditions: Thebehaviour of materials under high pressures, high temperatures,high magnetic and electric fields is still poorlyunderstood. Such studies are complicated and require expensiveand sophisticated instrumentation, but have becomepossible with the availability of equipment for producingextreme external fields.Dynamic and dissipative phenomena at surfaces and interfaces:With further developments in nanotechnology, theneed to understand dissipative phenomena, lubricationand friction on an atomic level and in systems confined tothe nano-scale will increase rapidly. These studies will ultimatelylead to in situ studies of atomic friction on ultrashorttime scales. Microscopic insight into the structuralchanges that take place during corrosion and catalytic andelectrolytic reactions are of fundamental importance forthe active control of these chemical reactions, in whichboth molecular reactivity and surface morphology play arole. It has become clear during the last few years that theultimate understanding of these (also technologically important)physicochemical phenomena requires microscopicinformation of the dynamic behaviour of both electronsand nuclei. This information can only be obtained usingspectroscopy-microscopy and spectroscopy-diffractiontechniques in real time (see Sect. 9.1.4).MATERIALS SCIENCE AND BASIC RESEARCH IN EUROPE:CONCLUSIONS AND RECOMMENDATIONS291

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART292MaterialsStructurephases, microstructureExternal fieldspressure, temperaturemagnetic and electric fieldsPHENOMENAequilibrium non-equilibriumelectric magnetic optical mechanical thermalsemiconductors magnetic domains plasticity phase transitionssuperconductorscrack propagationspin-dependent transportshape memorydielectricsstrain-induced phenomenaAdvanced Analytical TechniquesInteractionsbondings, correlationsTheory and ModellingNanotechnologySurfaces andInterfacesConfinementLow Dimensionsand SymmetriesInterdisciplinarityatom controllithographyselfassembly…corrosioncatalysiselectrolysissolid-liquid interfacesproximity effectsnmnanometrescalequantum confinementtailoring/control2d-phenomenamagnetic interlayer couplingshape dependent phenomenafsfemtosecondscaleorganic-metal interactionssoft matter-hard matterbiocompatibility…Fig. 9.1. Materials phenomena: interrelation between materials,modelling, analysis and future trends.9.1.2. Synthesis and ProcessingSynthesis and processing are fundamental to materialsR&D, with new or improved methods usually leading tonew materials or superior properties. Synthesis andprocessing are also responsible for the production of highquality, low cost products throughout the manufacturingindustry. The main areas of innovation in synthesis andprocessing are:• increased control over complexity, composition, structure,and function;• water-based solution chemistry for low-cost, environmentallybenign synthesis;• rapid forming for use in combinational chemistry andthe search for new materials;• tailoring of materials at all length scales, from the atomicto macro-scales;• computer modelling of complex phenomena to improveunderstanding and control;• thin films and coatings for improved properties and componentlifetimes;• supercritical fluid chemistry for preparing new materialsand nanomaterials as oxides, nitrides, metals withcontrolled both shape and size, continuously frommicronic to nano-scales.Basic research is still needed in the areas of crystal growth,vapor deposition, sintering, phase transformation, andrheology to better understand how they affect and can becontrolled during synthesis and processing. Fig. 9.2 outlinesthe main areas of development for these techniquesin the future.Recommendations for priority research areas in materialssynthesis and processing are:MiniaturizationMiniaturization will be one of the most important goals ofmaterials synthesis and processing in the near future. Newprocessing technologies will be required to create all kindsof materials on ever smaller length scales. These techniqueswill enable manipulation of individual nanostructuredunits and atoms, and should be amenable to auto-

mation and parallel processing so that combinatorial approachescan be used to discover and optimize materials.Biomimetics and biomaterialsThe field of biomimetics is one of the most challengingfields for synthesis and processing of organic materials. Inmedicine, new biomaterials are urgently needed for avariety of uses (e.g., implants, biosensors). It is still notclear, however, how such materials can be synthesized in awell-controlled and reliable fashion, since the knowledgeon biomineralization and other natural synthesis processesis still in its infancy.Complex structures with building blocks/assembliesComplex, functional structures or assemblies are constructedfrom building blocks on both the nano- and themeso-scales. Structure development is driven by selforganization.The confinement of highly dispersed NanoBuilding Blocks (NBBs) in hybrid or inorganic matricesor the organization of NBBs on textured substrates couldprovide larger concentrations of active dots, better definedsystems, avoid coalescence into larger ill-defined agregateswhile keeping or enhancing specific magnetic, optical,electrochemical, chemical and catalytic properties intothe nanostructured hybrid materials.Interface engineeringInterface engineering is an increasingly important meansof improving and optimizing all kinds of materials frommetals, ceramics and superconductors to bio- and smartmaterials. This field includes processing and tailoring ofsurfaces and interfaces for special applications like microelectronicsand catalysis. Miniaturization results in interfacesbecoming one of the dominant defects in a material;in some cases, these interfaces are necessary to obtainspecific phenomena. Interface engineering is therefore avital component of many future technologies.Modelling and automation of materials synthesis andprocessingTrial-and-error experimental approaches are inefficientways of designing and discovering materials. Modelling ofsynthesis and processing is a powerful tool for decidingwhich directions to pursue, and which are non-feasibleor uneconomic. These techniques have proven valuablefor many years in traditional fields, like steel processing.Although urgently needed, modelling of nano- and biomaterialsprocessing has only just begun. Automated processingmust be sufficiently accurate if it is to be used fornano-fabrication.MATERIALS SCIENCE AND BASIC RESEARCH IN EUROPE:CONCLUSIONS AND RECOMMENDATIONS293Fig. 9.2. Activities to be pursued in developingadvanced synthesis and processing techniques.Manpower- development of data bases- interdisciplinary research groups- establishment of competence centresMATERIALSPROCESSING ANDSYNTHESISPrediction of properties as a functionof microstructure (structure, chemicalcomposition, bonding, size,…)Modelling- generalization of models- development of new methods- combinbation of modelling for different length scalesTailoring of microstructure- bulk materials- defect density- chemical compositionelectronic structure- interface engineering- surfaces (gas/solid)- internal interfaces- electronic structureTailoring of properties- optimization of mechanical,electrical, optical, magneticproperties- materials with novel propertiesNew materials and combination of different materials systems- electronic and functional materials on the basis of biomaterials,polymers, metals and ceramics- implants- biocompatibility, biosensors,…- single electron transistors, high-density storage devices,…- catalysis,…- optimization and development of materials for extreme conditionsNovel processes- combinatorial approaches- parallel processing- automation- combination of processing and analysis- combination of different processing routes- adaption of processes from nature- nano-fabrication- manipulation of single molecules- nano-structuring

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART2949.1.3. Advanced Analytical TechniquesProgress in materials science is intimately related toachievements in the development of dedicated analyticaltechniques which enable us to examine the atomic andelectronic structure of materials on the nanometre leveland to unravel and quantitatively analyze condensed matterphenomena and processes. The current and future rolesof modern techniques in the analysis of materials aresummarized in Fig. 9.3.Future targets in the design and processing of new materials,and monitoring and control of new phenomena andproperties, are the generic driving forces for the developmentof new concepts and new techniques in diffraction,microscopy and spectroscopy. The highest possible resolutions,greatest sensitivities, and ultimate detection limitsare the chief goals of this field, along with performing nondestructiveand in situ analysis. One consequence of developmentsin this area will be that the traditional boundariesbetween the three major analytical methods (diffraction,microscopy, spectroscopy) will gradually disappear.One possible scenario for how this key field of materialsscience can be organized in Europe is shown in Fig. 9.4.The following challenges in advanced analytical techniqueswill need to be met in the next decades:High resolution microscopyTo obtain local, non-averaged structural information aboutinhomogeneous materials and structures, improved instrumentresolutions will be needed to access smaller spatialdomains, e.g.,• sub-Å and sub-eV resolution in high resolution electronmicroscopy,• 10 nm spatial resolution in X-ray microscopy.Real time characterization of materials and phenomenaon femtosecond time-scalesThe ultimate goal of this endeavour is to observe atomicmotion in materials, particularly during chemical reactionsand biological processes, directly. The same techniquescould be used to control short-time relaxations of electronsand atoms during materials processing (e.g., modifyingmaterials by ion beams). Quantifiable objectives include:• 1 fs time resolution in laser spectroscopy• 10 fs time resolution in X-ray diffractionAchieving these ambitious goals, and thereby providingrevolutionary insights into materials, will require new andexpensive equipment and facilities, e.g., free-electronX-ray lasers. Such large-scale facilities can only be builtand operated on a European level with strong commitmentfrom Member States.Fig. 9.3. The role of advanced analytical techniques for materialsscience, including future goals and targets.DiffractionX-Rays (SR), Neutrons, Electrons, IonsMicroscopyElectrons, X-Rays (SR), Atom ProbesSpectroscopyLasers, Neutrons, X-Rays (SR), Electrons, NMRMaterialsAdvanced Analytical TechniquesCharacterizationDetectionPhenomenaOrdered StructuresCrystals and Artificial StructuresDisordered StructuresDefective and Amorphous MatterLiquidsInhomogeneous MatterElectronic andMagnetic StructuresSemiconductorsSuperconductorsComplex MagnetsFuture Goals (Selection)Spatial ResolutionTEM: Sub-ÅngstrømX-Rays: 10nmTime ResolutionLasers: Sub-fsX-Rays: 100–50 fsecEnergy ResolutionNeutrons: neVTEM: Sub-eVFuture TargetsInterfacial StructuresNano-Systems, ConfinementSoft and Bio-MaterialsSelforganizationPhase TransitionsKinetics and MetastabilityCompeting InteractionsExcitationsLifetime PhenomenaTransportHigh-T c SuperconductivityIonic TransportDiffusionResponse FunctionsMechanical, Electrical, MagneticOptical

Novel European FacilitiesLinac-Based X-Ray Sources, Pulsed Neutron SourcesSynchroton RadiationNeutrons, IonsNew Analytical ConceptsDetection Limits…Novel InstrumentationAccessing new Spaceand Time DomainsCrossdisciplinary AnalyticalTechniques…Large Scale FacilitiesEuropean Centresof ExcellenceDiffractionMicroscopySpectroscopy+Analysis of Interfaces and NanosystemsSoft- and BiomaterialsEuropean Advisory Board“Large Scale Facilities”Local contactsFellowshipsGraduates, PostgraduatesSenior FellowshipsExchange ProgrammesTraining ProgrammesEuropean ConferencesWorkshopsSummer SchoolsPractical Courses…MATERIALS SCIENCE AND BASIC RESEARCH IN EUROPE:CONCLUSIONS AND RECOMMENDATIONS295(SR-) X-Rays and NeutronsTEM, Atom Probes, NMR, Laser SpectroscopyInterdisciplinary NetworksMobility ProgrammesFig. 9.4. European action plan for advanced analytical techniques.Efficient use of European large-scale facilities and moderntechniques in materials analysisNew concepts in analysis are often developed by solid statephysicists in dedicated laboratories or large-scale facilitieswith little or no contact with the materials scientists whocould apply new techniques to the solution of “real world”problems. The efficient transfer of new ideas and breakthroughsin diffraction, microscopy and spectroscopy tothe materials science community needs to be promoted byholding cross-disciplinary workshops and training courses.The institutes housing state-of-the-art facilities shouldalso provide professional assistance to outside parties andact as “local contacts” with developers of new techniques.Creation of analytical networks and centres of excellenceThe full potential of current and future analytical methodsand apparatus can best be exploited if networks and centresof excellence are created which manage world-class facilitiesand provide high quality research and training opportunities.9.1.4. Materials Theory and ModellingComputational materials science and engineering providepowerful tools for:• prediction of novel structural and functional materials,e.g., nanomaterials,• optimization of complex materials/design solutions• simulation of materials synthesis, processing, microstructuresand properties,• development of history-dependent and of scale-bridgingmulti-scale simulation concepts,• integration of electronic and atomic level as well as continuumscale approaches,• studying phenomena that are not easily accessible byexperiment,• solving cost and time constraints for materials developmentand application.A large number of computer modelling techniques areavailable for studying all kinds of materials and their behaviourfrom the quantum and atomic levels to microstructuraland macroscopic levels over various time spans.Materials modelling will play an increasingly importantrole in materials design and the understanding of bothfundamental and complex processes in all materials. Themajor themes for materials theory and materials modellingto be pursued within the EC over the next ten years aresummarized in Fig. 9.5.The following recommendations are made for ensuringEurope remains at the forefront of computational modellingof materials:• Supercomputer facilities need to be installed or upgradedat more sites for large-scale simulations of fundamentalmaterials processes and phenomena, e.g., sintering,crack propagation, catalysis.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART296• Interdisciplinary teams are needed to develop robust softwareand examine complex phenomena and materials.• Computer laboratories in materials science departmentsneed to be expanded and upgraded to include the latestPCs, workstations and simulation software tools.• Training courses in materials modelling should be heldregularly throughout Europe for students, academic andindustrial researchersNew theories of the future• Mesoscopic theories• Many-body quantum theories• Ab initio• Networks for materials modelling are needed to aid longterm,large-scale simulation projects.• Development of multi-scale modelling techniques shouldbe given greater priority. This could be done by organizingcollaborative projects between groups specialising indifferent simulation methods and length/time-scales.• Collaboration between industry and academia in the developmentof simultation methods should be promoted.Modelling of complex material (small length-large time scales)• Biomaterials• Biomimetic materials• Functional materials• Polymers• Nanomaterials• Metastable and inhomogenous materialsComputing infrastructure• Supercomputers• Computer networksNew modelling strategies• Multiphysics and multiscale modelling• Data processing and analysis• Linking theory with experiments and new technologiesModelling of Industrial Materials (large length-large time scales)• Metals/Alloys• Ceramics• Glasses• PlasticsModelling of Materials Processes• Materials synthesis• Microstructural evolution• Materials performance and properties• Complex processing methods• Component and assembly performance• End-of-life recyclabilityFig. 9.5. Research priorities for materials modelling over the next decade.9.2. Materials SystemsExisting MaterialsNovel MaterialsNew discoveries• new compounds,new properties• new structuresOptimizing usage of material• System and process design• Materials recyclingDesigning on the small scale• Nanotechnology• BiomaterialsOptimizing Materials Production• Process modelling• Modelling of propertiesFig. 9.6. Overall strategies for improvement of advanced materials intothe 21 st Century.Materials can be divided into two broad groups; inorganicand organic materials. Inorganic materials are composedof non-carbon-based matter such as metals, ceramics andmetalloids (e.g. silicon and germanium). Organic materialsare based on carbon compounds, and include bothliving tissue and synthetic polymers. Materials can alsobe divided according to their properties or main applications,e.g., semiconductors, nanomaterials and catalyticmaterials. Technological progress in materials sciencecan be brought about by modifying and improving existingmaterials or by developing novel materials resultingfrom new discoveries. These concepts are outlined inFig. 9.6.

Superconductors• high T c materials• SQUIDS• computer componentsEnergy and Power• storage, e.g., Li batteries• production: solar cells, fuel cells(SOFCs, PEMs)• distribution: superconductorsErgonomics and the Environment• temperature sensors, flat screen TVs• micropositioning devices• separation membranes, catalysts• electrochromic glasses, filters• radioactive waste encapsulationNanoconductors• nanowires, nanotubes• single-electron conductors• spintronicsIT and TelecommunicationsOptics and Photonics• lasers, optical fibres• phosphors, scintillators• wave guidesApplication ofInorganic MaterialsSemiconductors• wide band gap materials• II-VI compounds,III-V compoundsTransportation• engine components• turbine blades, ceramic coatings,superstructures, nose cones• structural materials, e.g.,MMCs, ceramics, polymer compositesLife Sciences• biomaterials, biosensors• diagnostic tools• surgical instruments• drug delivery systemsMagnetic Materials• storage media• reading heads• computer memoryMATERIALS SCIENCE AND BASIC RESEARCH IN EUROPE:CONCLUSIONS AND RECOMMENDATIONS297Fig. 9.7. The diversity and range of applications of inorganic materials.9.2.1. Inorganic MaterialsResearch into advanced inorganic materials over the nextten years will reap benefits for five important sectors of theeconomy (Fig. 9.7). In all cases, basic research will bedirected towards developing new synthesis methodsallowing greater control over structure formation andsmaller scale components. Research should also be directedat discovering new materials and compositions, structuresand phenomena that will spawn new technologies,and revolutionize the way we manufacture goods, conductbusiness and spend our leisure time.(a) Metallic materialsMetals and their alloys have the potential for further largeimprovements in properties and performance during the21 st Century. Due to their high stiffness, ease of forming,strength over a wide range of temperatures and, most importantly,their reliability, metals are the materials of choicefor many engineering applications. They also often serveas the main phase in composites and adaptive systemsbecause of their attractive properties. They range from lowcostbulk materials used in civil engineering to advanced,high added value materials tailored at the atomic level. Theneed to improve their corrosion resistance and their potentialfor recycling are important reasons for maintaininga high level of scientific, technical and industrial R&D inthis field.The basic scientific challenges lie particularly in pursuingfundamental and long-term oriented research in this fieldthat is aimed at the development of well-tailored structures.Major challenges lie in the development of lightweightstructural materials, self-organizing microstructures, failure-tolerantmaterials systems and smart materials.Metallic materials can be divided into four categoriesaccording to their present and future impact on economicand industrial activities, as summarized in Fig. 9.8. Importantareas of metals research for the future include:• Microstructural design of structural metals, alloys andtheir compositesMuch remains to be understood concerning the microstructuraldesign and optimization of multiphase metallicmaterials, which represent a large fraction of engineeringstructural materials. The corrosion and heat resistanceof steels could be improved by better microstructuralcontrol, particularly at interfaces. Metal matrix compositesalso lend themselves to the systematic exploration ofvariations in multiphase metallic microstructures. Otherimportant objectives include developing high strengthto-weightratio structural materials, self-organising microstructures,failure-tolerant materials systems and smartmaterials.• The physics of plasticity and damageBetter understanding is needed of the complex phenomenainvolved in deformation and fracture of metals, alloys,and metallic composites. New techniques for modellingthe micromechanical behavior of materials that incorporatesubstructural phenomena (i.e., dislocations, boundaries,interfaces, and microvoids) coupled with focusedexperimental work should achieve this.

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART298Well-developed industrialmaterials• Complex metallurgyUnderstanding of phase transformations and microstructuraldevelopment in multicomponent alloys (e.g., superalloysand tool steels) has vastly improved with the adventof computer codes such as Thermocalc: This researchneeds to be pursued further for (i) improved understandingof the fundamentals of the thermodynamics and kineticsof phase transformations, (ii) improved understandingof microstructure/property relations of each componentfrom the atomic to macro-scales.• Liquid/solid processesMany materials processes involve the coexistence of aliquid with a solid, e.g., liquid phase sintering, rheo/thixocasting,and many composite fabrication processes. Thephysics of such processes have much in common, includingthe influence of capillarity, and fluid flow in the presenceof fine-scaled solids. Progress in understanding andmodelling these phenomena would provide significantbenefits in terms of reduced costs and higher quality formany materials classes (composites, ceramics, metals).Materials under developmentfor novel applicationsEmerging or future materialsComplex materials systemsSynthesis and treatment• low cost, reproducible processes• better control of properties• high quality, low cost materialsincreased competitivenessof European industryImprovement of known properties• surface treatments• rapid processing• powder metallurgyDiscovery of new properties• nanosized grains• high-pressure forming• atomic level controlNew concepts leading to advanced,innovative products• highly porous alloys (metallic foams)• nanocrystalline alloys• aperiodically crystallized alloysIntelligent composites• metal-ceramic-electronics composites• metal-polymer composites• grain boundary/interface engineeringSmart materialsFig. 9.8. Short-, medium-, and long-term research directions for metallicmaterials.• Functionally graded materialsMany structures require materials whose properties varyfrom one point to another. This leads to the concept of“functionally graded materials” (FGM), which have beenthe focus of several national research projects in Japan,the U.S. and Germany over the past ten years. Key challengesin this area are to lower the cost of processing, ascurrent FGMs are generally uneconomical.• Novel metallic materials and systemsUnconventional combinations of different metals, microstructuresand properties that have not yet been investigatedcould yield unexpected and useful materials. Novelsynthesis and processing techniques should be used to explorethese potential “goldmines”. Metals research shouldbecome more interdisciplinary, with metallurgists workingcloser with physicists, engineers, chemists and biologiststo come up with new multimaterial systems.(b) Ceramic materialsA wide range of advanced ceramics are being developed forfuture applications such as environmental sensors, electroniccomponents, turbine blades and fuel cells. Improvedprocessing and quality control will enable structural ceramicsto be used in niche areas such as aeronautics, space flightand power generation. The distinction between structuraland functional ceramics will become blurred as smartmaterials, nanoceramics and bioceramics are developed.The main directions which ceramics research will takein the future are summarized in Fig. 9.9. New designconcepts such as biomimicry, hyper-organization, complexcomposite architecture and nanotechnology, combinedwith the increased understanding and predictive powerprovided by computer modelling, mean that advancedceramics have a bright future. Challenges and foreseeabletrends for ceramics research in Europe include:Fabricating new architectures via microstructural controland new processing routes. The challenge is to create newclasses of materials exhibiting previously unimagined propertiesby controlling the structure at the nano-level and usinglow cost and environmentally benign synthesis routes.Integration of ceramics with other materials. In the future,ceramics will be combined with other conventional materialssystems, both inorganic and organic, to provide greater functionalityand reliability. These “smart” composites will be usedin both structural and functional applications, far beyond thecapabilities of most materials currently being used.Nanotechnology and miniaturization. Investigation and exploitationof effects occurring at the meso- and nano-scaleswill become increasingly important over the next decade.Decreasing the size of ceramic components and their constituentgrains can be expected to reveal a whole range ofnovel unexpected phenomena that can be put to use (e.g.,as sensors or biomaterials).

Functional CeramicsElectroceramicsStructural CeramicsCeramic CoatingsBioceramicsSmart MaterialsCompositesMultifunctional Systems Synergistic Effects Multimaterial SystemsDesign of New Ceramics and Composites• Atomic level control • Functional gradients• Microstructural control • Multilayer hybrid materials• Defect control• Nanoceramics• Computer simulation • Novel processing methodsMATERIALS SCIENCE AND BASIC RESEARCH IN EUROPE:CONCLUSIONS AND RECOMMENDATIONS299New PhenomenaImproved PropertiesOptimized FunctionsFig. 9.9. Future advanced ceramics, including design concepts and goals.Increasing functionality of ceramic materials. A wholerange of new compounds and ceramic materials are beingdiscovered with unusual properties that can be used in applicationssuch as electronics, photonics, lasers, recordingmedia, sonar, sensors, displays, batteries, infrared detectors.Intense effort is needed if Europe is to reap therewards from this rich area of research.Important recommendations for promoting ceramicsresearch in Europe are:Greater uptake of advanced ceramics by industryIndustry should be actively encouraged to incorporate thelatest advanced ceramics into their products; althoughinitial outlay can be greater, ceramics are generally longerlasting,lighter weight and more heat-tolerant than alternativematerials, so that greater savings are made in thelong run. Ceramics also can provide more functionalitiesthan cheaper, high volume materials.New initiatives in ceramic scienceThe EC should fund new European-wide initiatives todevelop advanced ceramic materials, especially ceramicmatrix composites, bio- and electroceramics. Fundingshould be raised to a level comparable to that in Japan,which currently leads in the development and uptake ofceramic technology. These initiatives should include substantialindustrial participation to ensure a critical mass ofresearchers and availability of the latest equipment in thishigh-investment, high-returns field.Establishment of a European ceramics instituteA European institute dedicated to advanced ceramics andcovering the whole spectrum of these materials, includinginterdisciplinary areas such as bioceramics and nanoceramics,would greatly aid uptake of ceramics technologyby smaller companies, as well as promote standardizationof property measurement, materials quality, and European-widecollaboration.(c) Amorphous solids - glassesLong term research into the innovation of new vitreousmaterials merits special encouragement. This includes thediscovery of brand new glass families by the control of subtleinteractions among complicated sets of atoms, as wellas the mastery of industrial compositions from a chemicalbonding point of view. Huge efforts should be made in theunderstanding of the glass formation mechanisms and themodelling of glass structures.(d) Structural composite materialsComposites offer the possibility of creating materials withsuperior properties or improved functionality by combiningtwo or more disparate materials to form a single materialssystem. The main types of composites currently beinginvestigated include polymer composites, metal matrix

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART300composites and ceramic matrix composites. In the futurewe can expect to see an increasing use of biological materialsin composites, particularly as research into biomimeticmaterials takes off and nature’s secrets for producing ultrahardbut tough materials from the atomic level are revealed.The main areas of future composites research should be:• Smart composites incorporating sensors and actuators,• Interface studies, particularly of delamination and internalfriction;• Computer modelling of complex architectures andshapes;• Metal matrix, ceramic matrix and polymer matrix compositesengineered on the nano-scale for use in differenttemperature regimes and exhibiting unique and superiorproperties;• Development of new systems, e.g., aluminium-based alloysreinforced with silicon carbide and alumina particles,whiskers or fibres.One of the greatest challenges for researchers is to understandthe many complex interactions between the componentsof these materials. This requires a systematic approachto understanding, design and production. The creationof a Centre of Excellence for Structural Compositeswould provide for an integrated multipartner approachto elucidating the fundamentals of processing, design,optimization, and industrial implementation. This wouldadvance the technology significantly and strengthenEurope’s position in the field, in which it currently lagssignificantly behind North America. Transportation, electronicpackaging, power transmission, aerospace, andsports technology, to name presently established applicationareas, would all benefit from improvements in thisfield.9.2.2. Organic, Bio- and Biomimetic Materials(a) Polymeric materialsThe field of polymeric materials is broad and extends frombasic synthetic chemistry to process engineering. Researchhas traditionally been pursued in the laboratories of largechemical corporations and chemistry or chemical engineeringdepartments of universities and research institutes.In the last few years a grown interest has emerged incombining knowledge from polymer science and otherdisciplines. Therefore the potential for creating new andinnovative materials is enormous.Basic research is still needed in many areas of polymerscience. Model polymeric materials (low molecular, compositionaland structural heterogeneity) are very importantin order to understand the basics of structure-propertiesrelationships. Priority research topics in polymer basedmaterials are listed below and summarized in Fig. 9.10.New synthesis methods:• New mechanisms of polymerization, e.g., catalytic,enzymatic and free radical polymerization in dispersedmedia (emulsions, miniemulsions, etc) and under supercriticalconditions• Environmentally friendly methods using water as asolventEnvironmentally FriendlyPolymers• solvent free polymerization• polymerization in aqueous mediaOptimization of IndustrialProcesses• in situ monitoring ofpolymer synthesis• reactive extrusionNew Synthesis MethodsWell-defined Architectures• non-linear multiblock polymers• hybrid, branched and dendriticco-polymersNovel Polymerization Schemes• enzymatic and catalytic polymerization• template polymerization• free radical polymerization• combined polymerization schemesComputer Modelling• dynamic processes• conformation and structure prediction• multi-scale modellingResearch intoPolymeric MaterialsNew Characterization Techniques• attochemistry• in situ characterizationBulk Properties• self-assembly• rheology• confined geometries• optical, thermal,electric propertiesInterfacial Properties• adsorption, adhesion, etc• thin polymer films• interfaces with othermaterials, e.g., ceramics,metalsSolution Properties• self-assembly in solution(micelle formation)Functional Polymers• nanodevices• nanopatterning/templating• smart surfaces and interfaces• ion conductors and membranesFig. 9.10. Future research directions for polymeric materials.

• Nanopatterning via block copolymer self-assembly• Combining of polymerization methods or transformingof one active centre to another• Selective solubilization of low molecular weight compounds• High purity synthesisNovel architectures and materials combinations:• Composite materials for greater strength and functionality• Behavior at polymer interfaces• Nanostructured materials based on polymersFunctional polymers:• Polymers for optics and electronics, e.g. light emittingdiodes, displays, sensors, batteries• Membranes for fuel cells and batteries• Polymers for biomedical applications (see b) below)• High performance polymers (polyimides, fluoropolymers,etc.)• Organic-inorganic hybrid structures• Smart materials for sensing and responding to environmentalchangesStructure-property relationships• Computer modelling from atomic to macro-scales• Structural organization and design at the atomic/nano-level• Transport phenomena in ion-conducting andgas filtration membranes• High speed analytical techniques(b) Bio- and biomimetic materialsBiomaterials is a rapidly growing field of materials researchthat has important implications for the quality of life ofEurope’s ageing populations. The main research prioritiesare:• Understanding of the fundamental mechanisms ofbiomaterial-cell interactions and identificaiton of thequantifiable relationships between a material’s surfacecharacteristics and cell behaviour.• Development of smart biomaterials that are able to sensetissue responses and release biological signals accordingly.• Optimization of bone-bonding systems that can reliablyand practically achieve stable fixation of prostheses tobone.• Optimization of the architecture and microstructure ofsynthetic scaffolds to act as vehicles for three dimensionaltissue regeneration.• Development of systems that facilitate localized deliveryof genes to diseased tissue.Closely related to biomaterials are the biomimetics; thesematerials are synthesized by copying mechanisms and processesobserved in Nature to provide optimal structuresand properties. Biomimetics are used not only for medicalpurposes, but as structural, smart and functional materialsalso. Future research directions for both these fields aresummarized in Fig. 9.11.Europe is currently falling behind other regions in biomaterialsresearch despite having the expertise and knowhow.The strength of U.S. industry and size of its market isdrawing many companies and researchers overseas. Toremedy this situation, it is recommended that• a database of implants, etc, be created to follow patientrecovery over the long term.• biomaterials be recognized as a legitimate field ofresearch, e.g., by providing professorships, establishinguniversity schools/departments.New biomaterials: preparationand structure formationNew biomorphous / biomimeticmaterials and nanodevicesNew biomaterials:functions and applicationsBiomaterials• Metallic, polymeric, ceramic andnatural materialsBiocompatible Materials• Molecular design• Multiphase structures• Scaffolds for tissue engineeringBiotemplating• Infiltration of cells and tissueSelf-organization• Self-assembly processesHybrid Materials Devices• Bioorganic/inorganic composites• Multiscale designed materialsCellular and Modular Materials• Interpenetrating compositesAdvanced Artificial OrgansSmart Materials• Polymorphic systemsFig. 9.11. Future research directions for bio- and biomimetic materialsover the next decade.• the EC convene multidisciplinary teams of experts tocoordinate research efforts within the EU, and providethem with a boost in funding to establish biomaterialsresearch centres specialising in different areas such ascardiovascular surgery, orthopaedics, ophthalmology.MATERIALS SCIENCE AND BASIC RESEARCH IN EUROPE:CONCLUSIONS AND RECOMMENDATIONS301Nano-Tribology• Frictional and adhesive systems• Adaptive surfacesNanomechanics• New recognition or sensor principles• New sensor and actuator principlesNanospheres• Drug delivery systems for medicaltechniques

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART302• protocols for discussing various ethical issues surroundingthe development and use of biomaterials be established-regulatorybodies are needed to oversee research,particularly when patient trials are involved.9.2.3. NanomaterialsAlmost all future materials science will be based on nanotechnologicalconcepts. Materials will be able to be assembledlayer-by-layer or even atom-by-atom to generate newatomic arrangements with completely new properties.Nanomaterials are designed (and are used) today in avariety of forms, such as nanopowders, colloids, thin filmsand coatings, multilayers and laterally structured systems(from nanostripes and nanodots in semiconductor researchto nanopore filters made from polymers). We are alreadytoday able to connect semiconducting materials with magnetic,superconducting, organic and even biologicalmaterials with nanometre control. Nanoscale materialsscience is governed by three main phenomena: confinement,proximity and organization. The interplay of thesethree phenomena creates rich new areas for uncoveringnovel materials behaviour.Nanotechnology promises to revolutionize the way we liveand work, from manufacturing and medicine to computingand communications. Many new and clever combinationsof materials, molecules, atoms and ions will emergeover the next few decades that display unusual and unexpectedbehaviour, thus allowing the development oftomorrow’s devices and applications.The confinement of materials to length scales below thoseproducing ordinary macroscopic behaviour results in newspin and charge ground states, new electric and magneticpolarization textures, and new dynamics for polarizationreversal and charge transport. Exchange of spin, charge,strain, electromagnetic fields, or matter across interfacesleads to novel proximity effects that profoundly affect theproperties of neighbouring materials. These confinementand proximity effects can be precisely controlled throughnanoscale organization, where the properties of hybridmaterials are tuned by adjusting the feature sizes of theconstituent materials. Fig. 9.12 summarizes key areas ofresearch and applications in this field.Future challenges in the science of nanomaterials:• Nanoparticles, quantum structures, self-assembly materialsand nanobiomimetrics demand priority attentionin the near future.• Do we know all possible mechanisms which lead to selforganizedstructures?• Is it possible to stabilize at room temperature (STMmanipulated)structures consisting only of a few atoms?• Possibilities of designing nanostructures using organiccomponents (organic FETs, organic light-emitting devices,etc.) and nano-sized magnetic domains that allowhigh density data storage, exhibit tailored hysteresisX-ray OpticsTissue EngineeringModelling & AnalysisNanoprobesNanoindentationGrid TechnologiesBiometics‘Extreme’ NanoSpeed of Operation 3D Analysis3D-Replication ‘Caged’Interdisciplinary ModellingOptical Sweezers Self assembly Self OrganizationLive Cells UltrafiltrationFunctional TipsFunctional Tips DNA DevicesPhotosynthesisFilmsMaterialsNanoembossingFactory on a ChipMolecular TemplatesHealthcareChemistryMicellarPolymer MatricesSelf-replicationBiocompatible MaterialsNanostructuredNanoparticlesStructures Supramolecular SystemsCosmaceuticalsNanocompositeSurface PreparationIntelligent LabNanoemulsionsSelective CatalysisFullerenesDisease Targetting Ferro FluidsMicro to Nanoon a ChipTissue ScaffoldsHeat DissipationKey-lock MaterialsWafer BondingMolecularResists CapacitanceMicrofluidics MEMSChemionicsNerve Repair Sensors IT & Communications Fine LineEnergy & SustainabilityRoboticsLithographyMBE/MOVPE MethodsNanomachinesMembranesQuantum ComputingQuantum Wires and DotsPhotovoltaicsGas StorageAerogelsNanotubes, C 60 , CContacts70Frictionless BearingsPaper DisplaysMolcular MotorsContact printing Material for Harsh LubricantsQubit CoherenceSensorsSingle Electron DevicesEnvironmentsPolymer ElectronicsFerromagneticsGranular GMR-elementsNanotribologyFig. 9.12. A roadmap for nanomaterials research and applications in Europe.0–5 years>5 years

loops and can be switched at the highest speeds, needto be explored further.• Further progress in spintronics depends on basic experimentaland theoretical studies of ferromagnetic-semiconductinginterfaces and nanostructures whichpreserve the electronic polarization.• It is also important to realise that current technologies,particularly those based on semiconductor materials,are reaching their physical limits. Strong and coordinatedbasic research programmes are necessary now tocome up with new ideas for overcoming these barriers.• Nanotechnology is an essential part of any such strategy.For example, nanomaterials may open the door tonew devices in the fields of quantum computing, quantumelectronics, photonics and magnetics.• Formation of quantum dots and wires of uniform sizeand distribution will be a demanding research field,as will be the fabrication of materials architectures andfunctioning circuits from these components to formuseful devices.Nanomaterials is by its very nature a multidisciplinary fieldbringing together experimentalists, theorists and engineers,physicists, chemists and biologists. The challengesof this are accordingly big. Communication between thevarious disciplines can be significantly improved via coordinatedresearch programmes, particularly by establishinga nanomaterials network or centre of excellence. Europemust meet the challenge of creating the right balance ofresearch and training infrastructure that can be accessedby scientists from all member states if it is to remain atechnologically competitive into the future.For Europe to become competitive in the field of nanotechnologyit is imperative that:• funding for basic nanomaterials research be increasedto a level comparable to that in the U.S. and Japan, andnanotechnology and interdisciplinary research be givenhigh priority in European materials programmes.• interdisciplinary research centres dedicated to investigatingnanomaterials and the applications listed inFig. 9.12 are established.• industry and academia work together to develop newer,more innovative synthesis and characterization techniques.• research into self-assembly and biomimetic materialsbe increased.• computer modelling be used to predict the propertiesand phenomena of nano-size particles and nanodesignedmaterials.9.2.4. Electronic, Optical and Magnetic MaterialsBasic science in the fields of electronic, magnetic andoptical materials involves understanding and controllingelectrons and electronic correlations in materials and tailoredmaterials structures. Over the last two decades thisfield has uncovered many fascinating new phenomena,e.g., the quantum Hall effect (QHE), giant magnetoresistance(GMR), high-temperature superconductivity, andthe fractional quantum Hall effect (FQHE). Equallybreath-taking is the speed with which most of these fundamentaldiscoveries have entered today’s technology, e.g.,a new high-precision standard for defining the SI unit ofresistance, the ohm (using QHE), new reading heads inhard disks (based on GMR), or new superconductingdevices (from YBCO materials).NewElectronicandPhotonicMaterialsforInformationTechnologyNanotechnology- Nanofabrication- NanoelectronicsMaterials for Lighting• Substrates for epitaxy• UV/Blue/Green LEDsMaterials HT-Electronics, Solar Cells,Sensors, etc.Materials for Si-MOS Electronics• High-K materials as gate insulators• Materials for advanced metallization &interconnectsMaterials for Spin-Electronics• Quantum computingOrganic Materials for LED, Displays,Molecular Electronics• Organic LEDs• Nano-imprint technologyMaterials for Optical CommunicationSystems• Laser diodes• Photonic devices & circuitsNew Circuit Architecture- Biotechnology- Information Theory- Chemical EngineeringFig. 9.13. Research and development of new materials for theInformation Technology Summary of potential research areas withinputs from Nanotechnology and integration of novel architecturedesign concepts.Electronic materials encompass a broad range of substancesfrom semiconductors such as doped silicon, germaniumand GaAs, to electronic and ionic conductors madeof metals, polymers, and ceramics. Promising areas ofresearch include organic semiconductors, nanostructuredmaterials, quantum dots and wires, II-VI and III-V semiconductors,and self-assembling systems.MATERIALS SCIENCE AND BASIC RESEARCH IN EUROPE:CONCLUSIONS AND RECOMMENDATIONS303

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART304Many breakthroughs have occurred in the use of materialsfor optical applications, especially lasers and communicationdevices. Novel organic materials, polymersand ceramics with tailored optical properties have all beendeveloped. Optical materials research is one of the mostinnovative and rapidly developing fields of materialsscience and is continually resulting in new commercialproducts and discoveries.A renaissance in basic research of magnetic materials istaking place as a result of breakthroughs in colossal magnetoresistance,magnetic multilayers, magnetic propertiesof thin films, magnetic coupling between layers, giant magnetoresistanceand nanoparticle synthesis. This flourishingfield of materials science is characterized by closecollaboration between experimental and theoreticalshort termmid termSilicon technology will follow Moore’s law to the physicsmaterials limit.Advances in photonics technology will increasefibre optic bandwidth exponentially.Electronc and photonic technology advances, combinedwith increases in magnetic storage density, will acceleratecomputing and communication capabilities.Blue and white LEDs.New materils for ICs, new device structures forelectronics and photonics.Carbon nanotube-based electronics.Single electron transistors and memories.High Tc superconducting wires and films for devices suchas SQUIDs, microwave generators.Novel electronic and photonic materials and structures.Quantum state logic and computing; quantum wire andquantum dot electronic and optoelectronic devices inwide use.Recent discoveries of superconductivity in MgB 2 , polymersand high-pressure iron show that many surprises stillawait researchers in this area. The ceramic high temperaturesuperconductors will find their first commercial applicationin the next few years, but the search for new highertemperature superconductors should also continue.In particular, further work needs to be done on• optimizing microstructures and improving criticalcurrent densities,• searching for new superconductors with small anisotropyand high critical temperature,• developing and improving thin film deposition techniques,• the detailed analysis of the materials at the micro- andnanometre scale,• promoting exchange of scientific knowledge throughcreation of European networks.A possible road map for European research in these areasis given in Fig. 9.14. In order to be able to follow this,several focused European actions are necessary:• Establishment of interdisciplinary research centres forsemiconductor technology that can compete with largeresearch institutes in Asia and the U.S.• Increase funding for research projects examining thefundamentals and application of single electron devices.• Initiatives in electro-optic technology to develop nextgenerationcomputers and communications, particularlylaser devices and photonics.• Long-term projects to develop spintronics, quantumcomputing and other future technologies.• Formation of Centres of Excellence in superconductivityto hasten the introduction of high temperature superconductordevices for use in industry, medicine andtransport.• Greater industry-academia collaboration on ways ofimproving/optimizing electronic storage media andother devices based on recent breakthroughs in magneticmaterials.long termHybrid electronic, optical, and magnetic systems,spintronics.Hybrid electronic/biological systems, Molecular andorganic electronics/computers.9.2.5. Materials Applications and Related TopicsFig. 9.14. Future progress in electronic, optical and magnetic materialsin Europeresearch groups. Breakthroughs are expected in the developmentof magnetic nanowires, perpendicular recording,magnetic non-volatile recording materials, magneto-opticlayers, spin valves and molecular magnets. Most of theseresearch activities are intimately related with nanotechnologicaland interdisciplinary concepts (Fig. 9.14).Advanced materials are used in a diverse range of new andestablished technologies that underpin our current standardof living, and will make future technologies possible.While there is not enough room to discuss all of these here,a few examples are given of promising and topical, but alsoless well-known, areas of research to illustrate the diversityof needs for modern materials technology.(a) Materials for catalysisIn order to maintain and strengthen the world-wide leadingposition of European catalysis science and industry, anext generation technology platform for advanced catalysisresearch should be created, bearing in mind the needfor full integration of homogeneous, heterogeneous and

Full integration of heterogeneous, homogeneous and biocatalysis and computational catalysisIntegrated methods for functionalanalysis and theoretical description• In situ study of real catalysts• elementary step on atomic level• predictive theory for adsorption andreaction on surfacesHigh throughput technologies• novel synthesis chemistry• high quality assays• HT characterizationTechnology platform to develop, for instance:novel fuel cell catalystslean NO x catalystsenantioselective catalystssmall alkane oxyfunctionalization catalystsphotocatalytic hydrogen generation catalysts...Development of methods for therational synthesis of solids• analyze defect structure• control defect structure• predict structural stability• predict synthesis pathwaysMATERIALS SCIENCE AND BASIC RESEARCH IN EUROPE:CONCLUSIONS AND RECOMMENDATIONS305Research infrastructure• access to large scale facilities• dedicated experiments• multidisciplinary networks• centres of excellence bringing togetherexperimentalists and theoreticiansPolitical measures• facilitate participation of youngresearchers from non-member states• establish EU graduate schoolsystem to attract talents from allover the worldIndustry-Academia integration• funding for internship programme• dedicated industry-academiaworkshopsFig. 9.15. Future research directions for catalytic materials.biocatalysis, and including computational methods as anessential part. This technology platform should providethe enabling technology package for accelerated materialsdevelopment in catalysis on the basis of an improvedunderstanding of the controlling parameters and the processeswhich control these parameters on a fundamentallevel. The application of these enabling technologies willlead to new generations of catalysts for processes decisivefor a sustainable development (Fig. 9.15). The interplay ofthe different factors and the role of EU actions is summarizedin the following diagram.Research topics at the forefront of catalytic science include:• Selective oxidation• Environmental catalysis• Asymmetric catalysis• Combinatorial catalysisRecommendations for catalysis research in Europe include:• basic research into novel materials and catalytic mechanismsat the atomic level.• environmental legislation encouraging greater use ofcatalysts for pollution reduction and efficient processing.• greater industry-academic collaboration on promisingcatalytic systems.• establishment of a interdisciplinary European CatalysisInstitute or Network of Excellence (see Annex 1 inChapter 8).(b) Materials for fusion reactorsFusion technology promises to provide a limitless supply ofclean and cheap electricity. Its success strongly depends onthe availability of high quality structural materials that canwithstand extreme environments. Over the last thirty years,however, fusion research has conducted mostly by the engineeringcommunity, and materials improvement has beenlimited. Fundamental research will be vital for overcomingcurrent materials limitations. The development of fusionmaterials would be expediated by greater interactionbetween fusion scientists and materials scientists.(c) Materials for transportationThe transportation industry places extraordinary demandson the properties, performance and cost of materials becauseof considerations of safety, reliability, economy and design.To attain commercial success, materials engineering requiresthe simultaneous optimization of all these factors during theconversion of raw materials into products. The core purposeof this rigorous process of simultaneous engineering is toachieve an optimal balance between cost and product per-

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART306formance. It is therefore recommended that Europe establishstrategies for simultaneous development and engineeringof materials including, among other things:• rapid analysis techniques for complex systems• materials with improved reliability or self-repair capabilities• light-weight and energy-efficient materials• smart materials for responding to vehicle conditions andproviding passenger comfort.(d) Materials research in spaceSpace platforms offer the unique opportunity to probe materials,phenomena and processes in zero-gravity environments.This space-based materials research is potentiallyimportant for container-less studies and processes, forbasic studies of diffusive crystal growth, for the growthof semiconductors with low defect densities or for thesolidification of metals and glasses which may result inimproved casting technologies. The apparent drawback ofsuch experiments are the very high costs and risks involved.It is thus recommended• to further develop a European space-based materialsscience programme in a thoughtful manner whichincludes a careful analysis of the objectives and successprobability of the individual materials science projects.For microgravity studies which can be carried out withina couple of seconds it is also advisable to considerballistic rockets and fall towers as alternatives.9.3. Materials InterdisciplinarityMaterials science is by nature an interdisciplinary field,traditionally spanning engineering, chemistry and physics.The future of materials science will be in the further integrationof other disciplines such as biology, medicine andcomputing. Knowledge from these fields will hasten thedevelopment of materials science, resulting in new technologies,innovations and applications, e.g., organic computers.At the same time, the breadth of materials scienceand the phenomena it encompasses can only be understoodif researchers in different disciplines collaborate togenerate new insights and help solve problems. To fosterinterdisciplinary research, institutions should adopt aflexible structure with close contact and good communicationsbetween departments and disciplines.Some of the most promising areas of interdisciplinaryresearch in materials science are:• Bio-, biomimetic and self-assembly materials• Nanomaterials• Computer modelling (especially multi-scale modelling)• Smart materials• Surface and interface scienceAs an example, Fig. 9.15 shows how surface and interfacescience acts as an interdisciplinary platform. Our ability tocontrol the structure of interfaces on the atomic level hasmade it possible to create many new and fascinating interfacialstructures. Solid-solid interfaces in magnetic multilayermaterials result in unusual magnetic properties (e.g.,the giant magnetoresistance effect). A current topic of greatscientific interest and high application potential is the studyof interfaces between ferromagnets and semiconductors,with the objective of controlling the injection of polarizedelectrons into semiconducting devices. Interfaces betweenmetals or semiconductors on one side and organic materialson the other opens up completely new fields in functionalcoatings and organic semiconducting devices. Thecontrolled oxidation of surfaces may produce new nanometre-sizeddielectric and tunneling barriers required forfuture developments in the semiconductor industry.None of these projects in surface and interface sciencewould be possible without close collaboration betweenphysicists, materials scientists, chemists and (morerecently) biologists. It can safely be predicted that futureresearch will reveal novel structures, phenomena and propertieswhich do not exist naturally and which open up thepossibility of completely new functionalities.The five research areas listed above are by no means distinct,and will also bear upon one another in an interdisciplinarymanner; e.g., biomaterials designed at the nanolevel(i.e. bionanotechnology) could be used in the nextgeneration of smart devices. The materials developedthrough interdisciplinary collaboration promise to revolutionizeindustrial, medical and information technologies,and thus bring enormous benefits in terms of improvedstandards of living. Two ways of fostering interdisciplinary

solid-solid interfacesgrain boundariesnano-powdersmagnetic interfaces (domains)multilayers, epitaxyferromagnet-superconductor(proximity effects)ferromagnet-semiconductorspin injection, spintronicslithographySurface and Interface ScienceInterdisciplinary PlatformPhysicsMaterials ScienceNano-Technologysolid-liquid interfacescrystal growthwettingelectrolyteslubrication and frictionliquids in confinementself-assemblydynamiccontroldynamiccontrolMATERIALS SCIENCE AND BASIC RESEARCH IN EUROPE:CONCLUSIONS AND RECOMMENDATIONSChemistryBiology307solid-gas interfacesfunctional coatingshard-soft interfacesoxidationcorrosioncatalysisdynamic controlbiocompatible filmsorganic layersorganic FETorganic sensorsFig. 9.15. The interdisciplinary approach to surface and interface science.research are: i) establishing research institutes or labs inwhich researchers from two or more university departmentsor disciplines tackle related problems, and ii) linkingresearchers and institutes from different disciplinesvia networks to enhance communication and guideresearch in new interdisciplinary fields. Training programmesshould also be highly multidisciplinary in outlookso that researchers have a flexible range of skills andcan make new connections between different fields.It is therefore imperative that:• interdisciplinary research programmes in materialsscience are initiated on a European level,• interdisciplinary European workshops, training programmesand summer schools are organized,• interdisciplinary European research networks are set up,• funding agencies for different branches of science coordinatetheir activities to make it easier for interdisciplinaryprojects to be established.9.4. New Research Strategies and Infrastructures in Europe9.4.1 . Social Acceptance of ScienceSteps need to be taken to reverse the trend of decreasingnumbers of students in materials science courses at university,and the alienation of many members of the publicfrom science in general. These multi-faceted issues needto be tackled from as many different angles as possible:• restore public confidence in science by using publiclyfundedscience for the public good;• improve teacher training and school curricula to makescience exciting and attractive to pupils in primary andsecondary education;• engage the public on scientific issues of social relevancethrough TV programmes, live debates, science fairs andother events;

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART308• improve career structures and salaries for researchscientists (see below) to attract more students;• broaden science courses to include issues of socialrelevance, ethics and better communication skills.9.4.2. Political Support for ScienceMany areas of materials science require substantial investmentand support to perform cutting-edge experimentswith world-class equipment and facilities.• European governments need to increase funding forbasic science to levels similar to those in Japan and theU.S. if their economies are to remain strong in the 21 stCentury.• Breakthroughs in materials science are essential forbiotechnology, IT and other technologies that will determineour quality of life in the future. Materials scienceshould therefore receive similar funding levels to theseboom areas.• Academic scientists need to be better represented atnational and European levels, and should have a largersay in the science policy of the EC and Member States.9.4.3. Materials Science and Education in Europe(a) Basic science educationThe excitement and rewards of studying basic science needto be conveyed to youngsters as early as possible to ensurethat tomorrow’s Europeans value science and more of themtake it up as a career. Initiatives to do this should include:• science training and refresher courses for primary andsecondary school teachers,• visits to labs and large-scale facilities performing cuttingedgeresearch,• scientists visiting schools to talk to children about theadventure science, careers in science and scientificissues.(b) Role of universitiesAlthough collaboration with industry is important, theprimary function of universities should be to educatestudents and perform innovative and horizon-broadeningresearch. With renewed funding from their respectivegovernments, materials science departments throughoutEurope would be able to refurbish buildings and updateequipment so as to attract more students and increaseresearch output. Universities also need to be flexibleenough to establish new interdisciplinary, interdepartmentalcentres for working on the scientific fields of tomorrow,such as biomaterials, smart materials and nanoscience.(c) Human capital and research careersEurope has enormous potential for generating innovativeideas and new technologies because of its cultural diversityand long tradition of doing top-class science. In orderto realise this potential, increased mobility of researchers,particularly within the EU, is essential. Information aboutresearch opportunities in other countries should be distributedmore widely, the number of international researcherfellowships increased, and restrictive immigration lawsor university employment policies relaxed. Career structuresand salaries for research scientists should also be improved,e.g., by encouraging universities to provide moretenured positions rather than taking on postdocs. To meetindustry’s demands for more materials scientists and engineers,and to reflect changes and progress within society,more women and minority group students should beencouraged to take up materials science as a career.9.4.4. Training, Mobility and Public RelationsIn order to attract talented young people back to basicscience and research, fundamental changes in researchertraining and academic career structures are needed. Europeanuniversities and research laboratories need to provide:• more competitive salaries;• more attractive career options for young people,including job security;• more women students and lecturers/professors.Greater mobility of researchers, particularly within theEC, should be encouraged to foster professional developmentand cross-fertilization of ideas. This would be greatlyassisted by the creation of a European-wide qualificationfor materials scientists (EurMat) similar to that alreadyexisting for physicists (EurPhys).As well as learning technical skills, European researchersshould also receive foreign language training and communicationskills. The latter is especially important if scientistsare to communicate effectively with and convey theirthoughts and motivations to an increasingly skeptical public.For materials science and related technologies toprosper in Europe, better promotion of this field as a discipline/careerand improved public relations are vital.9.4.5. New Strategies for Basic Research in Europe(a) Overall strategiesEurope should aim to be number one in as many new materialstechnologies as possible. It is vital that Europeangovernments and the EC coordinate research efforts via

European-wide materials science programmes and networks• The EC should recognize the central role of materialsscience for technological development in its planning,funding and coordinating activities.• The EC should set up a European Materials Council towork together with national materials societies, institutesand research councils to ensure that Europe developsfirst-class facilities, and to respond to the morespecific needs identified in this White Book.• Research strategies for materials science should includeboth small-scale and large-scale projects to take intoaccount the needs of different Member States andresearch fields:(b) European research networksCreating research networks will allow a “critical mass” ofresearchers to be brought to bear upon complex, largescaleproblems, particularly interdisciplinary areas such asnano- and biomaterials. These networks could be formalizedas virtual research centres or Networks of Excellence,funded by the EC, and consisting of research groups andlaboratories from throughout the EU. The growth of theInternet should also be utilized to provide high speed communications.This would allow faster flow of information,better sharing of resources, and efficient allocation ofexpertise for teaching and guiding and evaluating projects.(c) Research facilitiesEurope already has excellent experience in successfullymanaging and operating large-scale facilities. The numberof large-scale research facilities accessible to materialsscientists should be increased in the medium to long termin order to attract the world’s best scientists and raise thestandard of European research even higher. Recommendationsconcerning new EC-managed facilities are:• Centres of Competence and Centres of Excellence inMaterials Science and Technology should be establishedaround Europe to house the latest apparatus and developnew analytical techniques.• Small- and medium scale laboratories should upgradedwith modern in house instrumentation• High Resolution Electron microscopy and High ResolutionLaser and NMR spectroscopy centres need to bedefined or created• Training programmes should be offered to researchers,technicians and engineers to ensure resources are maintainedand used most efficiently.• R&D into fourth generation (LINAC-driven) synchrotronsources and pulsed neutron sources should furtherbe pursued with the aim of constructing and running alarge-scale facility over the long term.(d) International collaborationInternational collaboration is a vital part of modern science:• Materials scientists should be encouraged to spend timeoverseas in other cultures and research environmentsin order to bring their newfound knowledge back toEurope.• Nationals from regions outside of Europe should be encouragedto work in Europe through generous fellowshipsand research positions.• International conferences should be held regularly andattended by researchers at all stages of their careersasthey sew the seeds for new innovative ideas and fruitfulresearch collaborations.MATERIALS SCIENCE AND BASIC RESEARCH IN EUROPE:CONCLUSIONS AND RECOMMENDATIONS3099.5. Closing RemarksMajor breakthroughs in materials science are expectedover the next decade, revolutionizing the way we manageand interact with our environment. Europe must utilize itsresources efficiently and maintain a critical mass of expertiseto continue at the cutting-edge of research. Equallyimportant is the promotion of materials science educationand careers to the younger generation.This White Book is intended to show the fundamental importanceof basic research in materials science to moderntechnology, and predict the directions it will take us in thefuture. As the driver behind many of today’s high-techindustries, materials science deserves the full support ofresearch councils, governments and the general public.It is hoped that the recommendations in this book will beimplemented so that European materials science andindustry prosper well into the 21 st Century. It is the responsibilityof educators, scientists, politicians, and otherprofessionals to ensure that Europeans grab hold of theenormous opportunities that these developments in materialsscience present.

APPENDIX IMAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGARTMax-Planck-Institut für Metallforschung Stuttgart, GermanyEU-Workshopon Strategies for Future Areas of Basic Materials ScienceH. Dosch, E. Mittemeijer, M. Rühle, M.H. Van de VoordeJune 13 - 15, 2000Schlosshotel Monrepos | Domäne Monrepos 22 | 71634 Ludwigsburg310Schedule of WorkshopJune 1312:00-13:00 lunch13:00-13:30 Welcome and introduction to the objective of this workshop (Rühle)13:30-16:00 Session on Materials (Raabe, Eberl, Aldinger, Wegner)16:00-16:30 coffee break16:30-18:30 Session on Materials (Raabe, Eberl, Aldinger, Wegner)19:00 dinner20:30-22:30 continue Materials, start Phenomena, or general discussionJune 1408:30-10:00 continue session on Phenomena (Kirschner, Arzt, Mittemeijer, Parrinello)10:00-10:30 coffee break10:30-12:30 continue session on Phenomena (Kirschner, Arzt, Mittemeijer, Parrinello)12:30 lunch14:00-16.00 Session on Characterization (Dosch, Rühle)16:00-16:30 coffee break16:30-18:30 Session on Characterization (Dosch, Rühle)19:00 dinner20:30-22:30 Session on Processing (Jansen)June 1509:00-10:30 Workshop Summary and Discussion on general issuesand on further action10:30-11:00 coffee break11:00-12:30 Workshop Summary and Discussion on general issuesand on further action12:30 lunch13:30 End of workshop

Working Group Topics Discussion leader ParticipantsMaterials Metals and Alloys, Composites Raabe De Hosson, Gottstein, Gösele, Vitek, van HoutteSemiconductors Eberl Forchel, Ploog, MadarCeramics and Ferroelectrics Aldinger Baumard, Flükiger, Maier, WaserSoft and Bio-Materials, Interfaces Wegner Bonfield, Ciardelli, Hadjichristidis, Hadziioannou,Johannsmann, Schmidt, VidalPhenomena Electronic Correlations Kirschner Buschow, FuldeSmall-Scale Materials Arzt Borghs, Gao, Prinz, SpaepenSolid-Gas, -Liquid, -Solid Reactions Mittemeijer Agren, Howe, SchlöglModelling and Theoretical Physics Parrinello Dietrich, Kremer, Neugebauer, PettiforCharacterization Diffraction and Spectroscopy Dosch Deville, Clausen, Findenegg, Kaindl, Keimer,Kunz,Louer, Miranda, Richter, SchneiderMicroscopy and Probe Techniques Rühle Bolt, Colliex, Smith, Urban, van TendelooProcessing Materials Synthesis Jansen Barboux, Etourneau, Kniep, Rey, SchüthAPPENDICESWorking groups should address the following issues: (a) state of the art 2000 +; expected trends 2000-2010 without focussed action; (b) expectedneeds 2002-2015: worldwide and EU (c) action to be taken in order to achieve (b); worldwide and EU needs could encompass: new initiatives, newmaterials, properties, new facilities, more manpower, interdisciplinary programmes, etc.311APPENDIX IIList of ParticipantsJohn ÅgrenMat. Sci. & Eng. Dept.Royal Institute of TechnologyBrinellvagen 23A100 44 StockholmSwedenTel +46-8-790 9131Fax +46-8-20 76 81john@met.kth.sePhilippe BarbouxPMC - CNRS UMR 7643Ecole PolytechniqueRoute de Saclay91128 Palaiseau CedexFranceTel +33-1 69 33 4663Fax +33-1 69 33 3004philippe.barboux@polytechnique.frBFritz AldingerMPI für MetallforschungHeisenbergstr. 570569 StuttgartGermanyTel +49-711-6861-201Fax +49-711-6861-255aldinger@aldix.mpi-stuttgart.mpg.deHarald BoltMPI für PlasmaphysikBereich MaterialforschungPostfach 15 3385740 Garching b. MünchenGermanyTel +49-89/3299-2141Fax +49-89/3299-1212Harald.Bolt@ipp.mpg.deEduard ArztMPI für MetallforschungSeestr. 9270174 StuttgartGermanyTel +49-711-2095-119Fax +49-711-2095 120eduard.arzt@po.uni-stuttgart.deStaf BorghsIMECKapeldreef 75B-3001 LeuvenBelgiumTel +32 16 281501Fax +32 16 281849Staf.Borghs@imec.beJean-François BaumardENSCI47 Av. Albert Thomas87065 LimogesFranceTel +33-5-55-45-22-28Fax +33-5-55-79-69-54jf.baumard@ensci.frWilliam BonfieldMat. Sci. & Met. Dept.University of CambridgePembroke StreetCambridge CB2 3QZUnited KingdomTel +44-1223-33 44 35Fax +44 1223 33 45 67wb210@hermes.cam.ac.ukJürgen BuschowVan der Waals-Zeeman LaboratoriumUniversiteit van AmsterdamValckenierstraat 65NL-1018 XE AmsterdamThe NetherlandsTel +31 20 525 5714Fax +31 20 525 5788Buschow@Wins.UvA.NL

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART312Brian CantorDept. of MaterialsUniversity of OxfordParks RoadCOxford OX1 3PHUnited KingdomTel +44 1865 283226Fax +44 1865 273738brian.cantor@materials.ox.ac.ukChristian ColliexLaboratoire Aimé CottonBâtiment 505Université Paris Sud91405 OrsayFranceTel +33 (0)1 69 35 20 05Fax +33 (0)1 69 35 20 04christian.colliex@lac.u-psud.frFrancesco CiardelliDpto di Chimica e Chimica IndustrialeUniversità di Pisavia Risorgimento, 3556124 PisaItalyTel +39-050 918229Fax +39-050 918320fciard@dcci.unipi.itJeff De HossonMaterials Science GroupUniversity of GroningenBldg. 13.41, Nijenborgh 4NL-9747 AG GroningenThe NetherlandsTel ++31 50 363 4898Fax ++31 50 363 4881hossonj@phys.rug.nlDKurt ClausenRiso National LaboratoryP.O. Box 49DK-4000 RoskildeDenmarkkurt.clausen@risoe.dkJean-Paul DevilleIPCMS - CNRS UMR 750423, rue du LoessBP 20 CR67037 Strasbourg Cedex 2FranceTél 03 88 10 71 41Fax 03 88 10 72 50jean-paul.deville@ipcms.u-strasbg.frSiegfried DietrichFB PhysikBergische Universität Wuppertal42097 WuppertalGermanyTel +49-202-439-2744Fax +49-202-439-2635dietrich@theorie.physik.uni-wuppertal.deHelmut DoschMPI für MetallforschungHeisenbergstr. 170569 StuttgartGermanyTel +49-711-689-1900Fax +49-711-689-1902dosch@dxray.mpi-stuttgart.mpg.deMarc DrillonIPCMS - CNRS UMR 750423, rue du Loess BP 20 CR67037 Strasbourg Cedex 2FranceTel +33-3 88 10 71 31Fax +33-3 88 10 72 50drillon@teutates.u-strasbg.frKarl EberlMPI für FestkörperforschungHeisenbergstr.1E70569 StuttgartGermanyTel +49 (0)711 6891312Fax +49 (0)711 6892923eberl@servix.mpi-stuttgart.mpg.deJean EtourneauUPR 9048 - I.C.M.C.B.Université Bordeaux I162, ave du Dr. Albert Schweitzer33608 Pessac CedexFranceTel +33-5 56 84 63 23Fax +33-5 56 84 66 34dr@icmcb.u-bordeaux.frGerhard FindeneggStranski-InstitutTU BerlinStrasse des 17. Juni 11210623 Berlin, GermanyTel +49-30-314-24171Fax +49-30-314-26602findenegg@chem.tu-berlin.derene.flukiger@physics.unige.chFRené FlükigerDPMCUniversité de Genève24, quai Ernest Ansermet1211 Genève 4SwitzerlandTel +41-22 702 6240Fax +41-22-702 6869Alfred ForchelLehrstuhl für Technische PhysikUniversität WürzburgAm Hubland97074 WürzburgGermanyTel +49 931/ 888 5101Fax +49 931/ 888 5143forchel@physik.uni-wuerzburg.dePeter FuldeMPI für Physik komplexer SystemeNöthnitzer Str. 3801187 DresdenGermanyTel +49 (351) 871-1101Fax +49 (351) 871-1199fulde@mpipks-dresden.mpg.de

Huajian GaoDiv. of Mechanics & ComputationDept. of Mechanical EngineeringStanford UniversityStanford, CA 94305-4040United StatesTe +1-650 725-2560Fax +1-650 723-1778gao@am-sun2.stanford.eduGUlrich GöseleMPI für MikrostrukturphysikWeinberg 206120 HALLE/SaaleGermanyTel +49(0)345-5582 657Fax +49(0)345-5582 557goesele@mpi-halle.deGünter GottsteinInstitut f. Metallkunde u. MetallphysikRWTH Aachen52056 AachenGermanyTel +49-241-80 68-60Fax +49-241-88 88 -608gg@imm.rwth-aachen.deNikos HadjichristidisUniversity of AthensDept. of ChemistryPanepistimiopolis, Zografou15771 AthensGreeceTel +30 1 -7249103, 7274-330Fax +30 1-7221800hadjichristidis@chem.uoa.grHGeorges HadziioannouLaboratory of Polymer ChemistryUniversity of GroningenNijenborgh 49747 AG GroningenThe NetherlandsTel +31-(0)50-363 4510Fax +31-(0)50-363 4400G.Hadziioannou@chem.rug.nlJames HoweMPI für MetallforschungSeestr. 9270174 StuttgartGermanyTel +49-711-2095-331Fax +49-711-2095-320jh9s@virginia.eduAPPENDICES313Martin JansenMPI für FestkörperforschungHeisenbergstr.170569 StuttgartGermanyTel +49-711-689-1500Fax +19-711-689-1502hamilton@jansen.mpi-stuttgart.mpg.deJDiethelm JohannsmannMPI für PolymerforschungPostfach 31 4855021 MainzGermanyTel +49 (6131) 379 163Fax +49 (6131) 379 360johannsmann@mpip-mainz.mpg.deGünter KaindlInstitut für ExperimentalphysikFU BerlinArnimallee 1414195 BerlinGermanyTel +49-30 838-529 77Fax +49-30 838-56560kaindl@physik.fu-berlin.deKBernhard KeimerMPI für FestkörperforschungHeisenbergstr.170569 StuttgartGermanyTel +49-711-689-1650, -1631Fax +49-711-689-1652, -1632keimer@kmr.mpi-stuttgart.mpg.deJürgen KirschnerMPI für MikrostrukturphysikWeinberg 206120 HALLE/SaaleGermanyTel +49-(0)345-5582-655Fax +49-(0)345-5582 566sekrki@mpi-halle.deRüdiger KniepMPI für chemische Physik fester StoffeBayreuther Str. 40, Haus 1601187 DresdenGermanyTel +49-351 208-4500Fax +49-351 208-4502kniep@cpfs.mpg.deKurt KremerMPI für PolymerforschungPostfach 31 4855021 MainzGermanyTel +49-6131-379 141Fax +49-6131-379 340kremer@mpip-mainz.mpg.deChristof KunzEuropean Synchrotron Radiation FacilityB.P. 220F-38043 Grenoble CedexFranceTel +33-4-76-88-2508Fax +33-4-76-88-2020cmoulin@esrf.frReinhard LipowskyMPI für Kolloid- u. GrenzflächenforschungAbt. Theorie14424 PotsdamGermanyTel +49-331-567-9600Fax +49-331-567-9612lipowsky@mpikg-golm.mpg.deL

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART314Daniel LouërLab. de Chimie du Solide et InorganiqueMoléculaireUniversité de Rennes 135042 Rennes CedexFranceTel +33-2 99 28 62 48Fax +33 2 99 38 34 87Daniel.Louer@univ-rennes1.frRodolfo MirandaUniversidad Autónoma de MadridCiudad Universitaria de Cantoblanco28049 MadridSpainTel +34-91 397 4234Fax +34-91-397 3970miranda@hobbes.fmc.uam.esRoland MadarLMGP - CNRS UMR 5628INPG - Bâtiment BRue de la Houille Blanche - BP 4638402 Saint Martin d’HeresFranceTel +33 4 76 82 63 30Fax +33 4 76 82 63 94roland.madar@inpg.frMEric MittemeijerMPI für MetallforschungSeestr. 9270174 StuttgartGermanyTel +49-711-2095-419Fax +49-711-2095-420mittemeijer@mf.mpi-stuttgart.mpg.deJoachim MaierMPI für FestkörperforschungHeisenbergstr.170569 StuttgartGermanyTel +49-711-689-1720Fax +49-711-689-1722weiglein@chemix.mpi-stuttgart.mpg.deBerthold NeizertMax-Planck-Gesellschaft zur Förderung derWissenschaften e.V.Postfach 10 10 6280084 MünchenGermanyTel +49-89-2108-1270Fax +49-89-2108-1200neizert@mpg-gv.mpg.deNJörg NeugebauerFritz-Haber-Institut der MPGFaradayweg 4-614195 BerlinGermanyTel +49 30 8413 4826Fax + 49 30 8413 4701neugebauer@fhi-berlin.mpg.deDavid PettiforDept. of MaterialsUniversity of OxfordParks RoadOxford OX1 3PHUnited KingdomTel +44 1865 273751Fax +44-1865-273 783david.pettifor@materials.ox.ac.ukLuigi NicolaisDipartimento di Ingegneriadei Materialie e della ProduzioneUniversità “Federico II”Piazzale Tecchio, 8080125 NapoliItalyTel +39.081.7682401Fax +39.081.7682404Klaus PloogPaul-Drude-Institut für FestkörperelektronikHausvogteiplatz 5-710117 BerlinGermanyTel +49-30-20377-365Fax +49-30-20377-201ploog@pdi-berlin.deMichele ParrinelloMPI für FestkörperforschungHeisenbergstr.170569 StuttgartGermanyTel +49-711-689-1700Fax +49-711-689-1702parrinello@prr.mpi-stuttgart.mpg.dePFritz B. PrinzMechanical Engineering Dept.Stanford UniversityBldg. 530, Rm. 220Stanford, CA 94305-3030United StatesTel +1-650-723-0084Fax +1-650-723-5034fbp@cdr.stanford.eduDierk RaabeMPI für Eisenforschung GmbHPostfach 14 04 44R40074 DüsseldorfGermanyTel +49 211 6792-278Fax +49 211 6792-333, 268raabe@mpie.deChristian ReyCNRS UMR 5085Physico-Chimie des PhosphatesC.I.R.I.M.A.T38 rue des 36 ponts31400 Toulouse Cedex 4, FranceFranceTel +33-561 55 65 32, -562 88 56 74Fax +33-561 55 60 85Dieter RichterForschungszentrum Jülich GmbHPostfach 19 1352425 JülichGermanyTel +49-2461-612499Fax +49-2461-612610D.Richter@fz-juelich.de

Manfred RühleMPI für MetallforschungSeestr. 9270714 StuttgartGermanyTel +49-711-2095-319Fax +49-711-2095-320ruehle@hrem.mpi-stuttgart.mpg.deRobert SchlöglFritz-Haber-Institut der MPGAbt. Anorganische ChemieFaradayweg 4-614195 BerlinGermanyTel +49-30-8413-4402Fax +49-30-8413-4401schloegl@fhi-berlin.mpg.deSHans-Werner SchmidtMakromolekulare Chemie IUniversität Bayreuth95440 BayreuthGermanyTel +49-921-55 3200Fax +49-921-55 3206hans-werner.schmidt@uni-bayreuth.deJochen SchneiderDESY, HASYLABNotkestr. 8522603 HamburgGermanyTel +49 40-8998-3815Fax +49 40-8998-4475schneider@desy.deFerdi SchüthMPI für KohlenforschungKaiser-Wilhelm-Platz 145470 Mülheim a. d. RuhrGermanyTel +49 (0)208 306 2372Fax +49 (0)208 306 2995schueth@mpi-muelheim.mpg.deGisela SchützPhysikalisches Institut derUniversität WürzburgAm Hubland97074 WürzburgGermanyTel +49 (0)931-888-5890Fax +49 (0)931-888-4921schuetz@physik.uni-wuerzburg.deAPPENDICES315Dan ShechtmanDepartment of Material EngineeringTechnionHaifa 32000IsraelTel +972-4-8294299Fax +972-4-8321978mtrdan@tx.technion.ac.ilGeorge SmithDepartment of MaterialsUniversity of OxfordParks RoadOxford OX1 3PHUnited KingdomTel +44 1865 273762Fax +44 1865 273789george.smith@materials.ox.ac.ukFrans SpaepenDiv. of Eng. & Appl. SciencesHarvard University29 Oxford StreetCambridge, MA 02138-2901United StatesTel +1 617-495-3760Fax +1 617-495-9837spaepen@deas.harvard.eduKnut UrbanForschungszentrum Jülich GmbHInstitut für FestkörperforschungPostfach 19 1352425 JülichGermanyTel +49-2461-61 3153Fax +49-2461-61 6444K.Urban@fz-juelich.deUMarcel Van de VoordeMPI für MetallforschungSeestr. 9270174 StuttgartVGermanyTel +49-711-2095-475Fax +49-711-22 657 22vandevoorde@mf.mpg.dePaul Van HoutteMTMK.U.LeuvenDe Croylaan 23001 Heverlee (Leuven)BelgiumTel +32 16 32 Tel. 1304Fax dept +32 16 32 1973Paul.VanHoutte@mtm.kuleuven.ac.beGustaaf Van TendelooEMATRUCAGroenenborgerlaan 171B-2020 AntwerpenBelgiumTel 0032-3-2180-262Fax 0032-3-2180-257gvt@ruca.ua.ac.beAlain VidalCNRS UPR 9069I.C.S.I.BP 2488, 15, rue Jean Starcky68057 MulhouseFranceTel +33-3 89 60 87 02Fax +33-3 89 60 87 99A.Vidal@univ-mulhouse.frVaclav VitekDept. of Materials Science & EngineeringUniversity of PennsylvaniaPhiladelphia, PA 19104-6272United StatesTel +1-215-898-7883Fax +1-215-573-2128vitek@sol1.lrsm.upenn.edu

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGARTRainer WaserIFFForschungszentrum Jülich GmbHPostfach 19 13W52425 JülichGermanyTel. +49 2461 61 5811Fax +49-2461-61-2550R.Waser@fz-juelich.deGerhard WegnerMPI für PolymerforschungPostfach 31 4855021 MainzGermanyTel +49-6131-379-130, -131Fax +49-6131-379 330gerhard.wegner@mpip-mainz.mpg.de316OBSERVERS:Joachim BillMPI für MetallforschungHeisenbergstr. 570569 StuttgartTel +49-711-6861-228Fax +49-711-6861-131bill@aldix.mpi-stuttgart.mpg.deGuestsFrank ErnstMPI für MetallforschungSeestr. 9270174 StuttgartTel +49-711-2095-323Fax +49-711-2095 320ernst@hrem.mpi-stuttgart.mpg.dePeter GumbschMPI für MetallforschungSeestr. 9270174 StuttgartTel +49-711-2095-129Fax +49-711-2095-120gumbsch@finix.mpi-stuttgart.mpg.deUlrich HillebrechtMPI für MikrostrukturphysikWeinberg 206120 HALLE/SaaleTel +49(0)345-5582-617Fax +49(0)345-5582 566hillebre@mpi-halle.deKatharina LandfesterMPI für Kolloid- u. GrenzflächenforschungAbt. Kolloidchemie14424 PotsdamTel +49-331-567-9509Fax +49-331-567-9502landfester@mpikg-golm.mpg.deValeria MeregalliMPI für FestkörperforschungHeisenbergstr.170569 StuttgartTel +49-711-689-1639Fax +19-711-689-1702meregalli@prr.mpi-stuttgart.mpg.deHans RieglerMPI für Kolloid- u. GrenzflächenforschungAbt. Grenzflächen14424 PotsdamTel +49-331-567-9236Fax +49-331-567-9202Hans.Riegler@mpikg-golm.mpg.deFerdinand SommerMPI für MetallforschungSeestr. 9270174 StuttgartTel +49-711-2095-417Fax +49-711-2095-420sommer@mf.mpi-stuttgart.mpg.dePeter WochnerMPI für MetallforschungHeisenbergstr. 170569 StuttgartTel +49-711-689-1926Fax +49-711-689-1902wochner@dxray.mpi-stuttgart.mpg.deStefan ZaeffererMPI für Eisenforschung GmbHPostfach 14 04 4440074 DüsseldorfTel +49 211 6792-803Fax +49 211 6792-333

APPENDIX IIIMax-Planck-Institut für Metallforschung Stuttgart, GermanyPresentation ofEC White Book on Fundamental Aspects in Materials ResearchH. Dosch, E. Mittemeijer, M. Rühle, M.H. Van de VoordeMarch 15/16, 2001Waldhotel Degerloch | Guts-Muths-Weg 18 | 70597 StuttgartAPPENDICES317AgendaThursday, March 1517.00 General DiscussionChair: Helmut Dosch (Stuttgart)ca. 19.30Buffet DinnerFriday, March 1608.30 Eduard Arzt (Stuttgart) Welcome08.40 Manfred Rühle (Stuttgart) Introduction and General OverviewPresentation of the White BookGeneral Materials Classes09.10 Jean Etourneau (Bordeaux) Inorganic Materials09.30 Piet Lemstra (Eindhoven) Soft Materials09.50 Klaus Ploog (Berlin) Functional Materials10.10 Thomas Elsässer (Berlin): New Research Tools10.25 Huajian Gao (Stuttgart) Materials Theory10.40 Coffee BreakSpecific Materials11.15 William Bonfield (Cambridge) Bio-Medical Materials11.25 Ferdi Schüth (Mülheim a.d.R.) Catalysis Materials11.35 Harald Bolt (München) Fusion Materials11.45 Helmut Kronmüller (Stuttgart) Magnetic and Superconducting MaterialsCross-Disciplinary Activities11.55 Eduard Arzt (Stuttgart) Small Scale Phenomena12.15 Wolfgang Pompe (Dresden) Interdisciplinarity12.30 Conclusions13.00 Lunch

APPENDIX IVMAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART318List of ParticipantsAEzio AndretaEC Research Directorate - GeneralRue de la Loi 2001049 BrusselsBelgiumTel. +32-2-296-0612Fax +32-2-299-1848Nicole.Abras@cec.eu.intHarald BoltMPI für PlasmaphysikPostfach 15 3385740 Garching b. MünchenGermanyTel. +49-89/3299-2141Fax +49-89/3299-1212Harald.Bolt@ipp.mpg.deEduard ArztMPI für MetallforschungSeestr. 9270174 StuttgartGermanyTel. +49-711-2095-119Fax +49-711-2095 120eduard.arzt@po.uni-stuttgart.deWilliam BonfieldDept. of Materials Science & MetallurgyUniversity of CambridgePembroke StreetCambridge CB2 3QZUnited KingdomTel. +44-1223-33 44 35Fax 44 1223 33 43 66wb210@hermes.cam.ac.ukPierre BétinSNECMA41 Rue Marcel Delattre33140 Villenave d’OrnonFranceTel. +33-5 57 35 50 31BFabio CarassitiDip. Ingegneria Meccanica e IndustrialeTerza Università di RomaVia Vasca Navale, 79C00146 RomaItalyTel. +39-06-55 17 3303Fax +39-06-55 17 3256f.carassiti@materials10.dimi.uniroma3.itPierre ChavelLab. Charles Fabry de l’Institut d’OptiqueUniversité Paris-SudCentre Universitaire - Bat. 503, BP 14791403 Orsay CedeFranceTel. +33-1-6935 87 41Fax +33-1-69 35 87 00pierre.chavel@iota.u-psud.frStefan EchingerGeneralverwaltung derMax-Planck-GesellschaftEPostfach 10 10 6280084 MünchenGermanyTel. +49-89-2108 1218Fax +49-89-2108 1256echinger@mpg-gv.mpg.deSiegfried DietrichMPI für MetallforschungHeisenbergstr. D170569 StuttgartGermanyTel. +49-711-689-1921Fax +49-711-689-1920dietrich@mf.mpg.deThomas ElsässerMax-Born-Institut für Nichtlineare Optik u.SpektroskopieMax-Born-Str. 2A12489 BerlinGermanyTel. +49-30-6392-1400Fax +49-30-6392-1409elsasser@mbi-berlin.deHelmut DoschMPI für MetallforschungHeisenbergstr. 170569 StuttgartGermanyTel. +49-711-689-1900Fax +49-711-689-1902dosch@dxray.mpi-stuttgart.mpg.deJean EtourneauI.C.M.C.B. - CNRSUniversité Bordeaux I87, ave du Dr. Albert Schweitzer33608 Pessac CedexFranceTel. +33-5 56 84 63 23Fax +33-5 56 84 66 34dr@icmcb.u-bordeaux.frRené FlükigerDPMC, Université de Genève24, quai Ernest Ansermet1211 Genève 4SwitzerlandTel. +41-22 702 6240Fax +41-22-702 6869rene.flukiger@physics.unige.chHuajian GaoMPI für MetallforschungSeestr. 9270174 StuttgartGermanyTel. +49-711-2095-519Fax +49-711-2095-520hjgao@mf.mpg.dePatrick HemeryDépt. Sciences Chimiques, CNRSMichel-Ange, 37594 Paris CedexFranceTel. +33-1-44-96-40-83Fax +33-1-44-96-53-70virginie.cosseron@cnrs-dir.frfF G H

Rüdiger KniepMPI für chemische Physik fester StoffeNöthnitzer Str. 3801187 DresdenGermanyTel.. +49-351 46 46 30 00Fax +49-351 46 46 30 01kniep@cpfs.mpg.deHelmut KronmüllerMPI für MetallforschungHeisenbergstr. 570569 StuttgartGermanyTel. +49-711-689-1911Fax +49-711-689-1912kronm@physix.mpi-stuttgart.mpg.deJean-Claude LehmanSaint-Gobain, Les Miroirs18, av. d’Alsace92096 La Défence CedexFranceTel. +33-1-47 62 30 27Fax +33-1-47-62-33-12jean-claude.lehmann@saint-gobain.comJPiet J. LemstraFaculteit Scheikundige TechnologieTechnische Universiteit EindhovenDen Dolech L25612 AZ EindhovenThe NetherlandsTel. +31-40-2473650Fax +31-40-2436999p.j.lemstra@tue.nlRolf LinkohrMember of EU ParliamentEU ParliamentRue Wiertz, BAT LEO 11G1531047 BrüsselBelgiumTel. +32-2-284-5452Fax +32-2-284-9452rlinkohr@europarl.eu.intMassimo MarezioIstituto MASPEC-CNRParco Area delle Scienze 37a43010 Fontanini-ParmaItalyTel. +39-0521-26 92 83Fax +39-0521-25 43 52marezio@maspec.bo.cnr.itMAPPENDICES319Carlos MiravitllesDirector CSICInstitut de Ciència de MaterialsCampus de la UAB08193 Bellaterra - BarcelonaSpainTel. +34-93-580-18 53Fax +34-93-580-57-29Achilleas MitsosDirector-GeneralEC Research Directorate - GeneralRue de la Loi 2001049 BrusselsBelgiumTel. +32-2-295 8560Fax +32-2-295 8046Eric MittemeijerMPI für MetallforschungSeestr. 9270174 StuttgartGermanyTel. +49-711-2095-419Fax +49-711-2095-420mittemeijer@mf.mpi-stuttgart.mpg.deRoger NaslainLab. des Composites ThermostructureauxUMR 5801 CNRS-SNECMA-CEA-UB 1Domaine Universitaire3, allée de La BoëtieN33600 PessacFranceTel. +33-5-56-84 47 05, -06Fax +33-5-56-84 12 25naslain@lcts.u-bordeaux.frLuigi NicolaisDip. di Ingegneria dei Materialie e dellaProduzioneUniversità “Federico II”Piazzale Tecchio, 8080125 Napoli, ItalyTel +39.081.7682401Fax +39.081.7682404“Nicolais”Piero PerloAdvanced Product TechnologiesCentro Ricerche FiatStrada Torino 5010043 Orbassano-TorinoItalyTel. +39-11-9083-576Fax +39-11-9083-337p.perlo@crf.itPKlaus PloogPaul-Drude-Institut für FestkörperelektronikHausvogteiplatz 5-710117 BerlinGermanyTel. +49-30-20377-365Fax +49-30-20377-201ploog@pdi-berlin.deWolfgang PompeInstitut für WerkstoffwissenschaftTU Dresden01062 DresdenGermanyTel. +49-351-463-1420Fax: +49-351-463-1422pompe@tmfs.mpgfk.tu-dresden.deLuisa PristaEC Research Directorate - GeneralRue de la Loi 2001049 BrusselsBelgiumTel. +32-2-296-1598Fax +32-2-295-8046Luisa.prista@cec.eu.int

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART320Dierk RaabeMPI für Eisenforschung GmbHPostfach 14 04 R4440074 DüsseldorfGermanyTel.: +49 211 6792 - 278Fax +49 211 6792 - 333raabe@mpie.deManfred RühleMPI für MetallforschungSeestr. 9270174 StuttgartGermanyTel. +49-711-2095-319Fax +49-711-2095-320ruehle@hrem.mpi-stuttgart.mpg.deS. RadelaarNetherlands Institute for Metals ResearchRotterdamse Weg 1372628 AL DelftThe NetherlandsTel. +31-15-278 25 35Fax +31-15-278 2591radelaar@nimr.nlFerdi SchüthMPI für KohlenforschungKaiser-Wilhelm-Platz 145470 Mülheim a. d. RuhrGermanyTel. +49 (0)208 306 2372Fax +49 (0)208 306 2995schueth@mpi-muelheim.mpg.deSJürgen Roemer-MählerBMBF53170 BonnGermanyTel. +49-1888-57-3192Fax +49-1888-57-3601juergen.roemer-maehler@BMBF.bund.deUlrich SchwarzAbt. TheorieMPI für Kolloid- u. Grenzflächenforschung14424 PotsdamGermanyTel. +49-331-567-9610Fax +49-331-567-9602Ulrich.Schwarz@mpikg-golm.mpg.deJosé-Lorenzo Vallés BrauEC - DG RTD /G/3Rue Montoyer 75Office 2/23V1040 BrusselsBelgiumTel. +32-2-2991757Fax +32-2-2958046jose-lorenzo.valles@cec.eu.intVaclav VitekDept. of Materials Science & EngineeringUniversity of PennsylvaniaPhiladelphia, PA W19104-6272United StatesTel. +1-215-898-7883Fax: +1-215-573-2128vitek@sol1.lrsm.upenn.eduMarcel Van de VoordeMPI für MetallforschungSeestr. 9270174 StuttgartGermanyTel. +49-711-2095-475Fax +49-711-2095-444vandevoorde@mf.mpg.deMarc Van RossumAdvanced Semiconductor Processing Div.IMECKapeldreef 753001 LeuvenBelgiumTel. +32 16 281 326Fax + 32 16 281 214vrossum@imec.be

APPENDIX VAuthor Contact PageÅgren, J. Physical Metallurgy, Materials Science & Engineering Dept., Royal Institute of Technology 153Brinellvagen 23, 100 44 Stockholm, Swedenjohn@met.kth.seAldinger, F. Max-Planck-Institut für Metallforschung 26, 153Heisenbergstr. 5, 70569 Stuttgart, Germanyaldinger@mf.mpg.deAntonietti, M. Max-Planck-Institut für Kolloid- u. Grenzflächenforschung 18014424 Potsdam, Germanypape@mpikg-golm.mpg.deAPPENDICESArzt, E. Max-Planck-Institut für Metallforschung 176Seestr. 92, 70174 Stuttgart, Germanyeduard.arzt@po.uni-stuttgart.de321Baumard, J.F. ENSCI 2647, Ave Albert Thomas, 87065 Limoges, Francejf.baumard@ensci.frBolt, H. Max-Planck-Institut für Plasmaphysik, Bereich Materialforschung 100Postfach 15 33, 85740 Garching b. München, GermanyHarald.Bolt@ipp.mpg.deBonfield, W. Dept. of Materials Science & Metallurgy, University of Cambridge 72Pembroke Street, Cambridge CB2 3QZ, United Kingdomwb210@hermes.cam.ac.ukBonnell, D. University of Pennsylvania, Dept. of Materials Science & Engineering 253Philadelphia, PA 19104-6272, United Statesbonnell@sol1.lrsm.upenn.eduBréchet, Y. LTPCM, ENSEEG/INPG 117BP 75, 38401 St. Martin d’Heres, Franceybrechet@ltpcm.grenet.frChartier, T. Université de Limoges, ENSCI 20447 à 73 Ave. Albert Thomas, 87065 Limoges, Francet.chartier@ensci.frChavel, P. Laboratoire Charles Fabry de l’Institut d’Optique, Université Paris-Sud 88Centre Universitaire - Bat. 503, BP 147, 91403 Orsay Cedex, Francepierre.chavel@iota.u-psud.frChevalier, J. GEMPPM - INSA de Lyon 32Bât. 502, 20 Ave. Albert Einstein, 69621 Villeurbanne Cedex, Francechevalier@gpmmail.insa-lyon.frClausen, K.N. Risø National Laboratory 243P.O. Box 49, 4000 Roskildekurt.clausen@risoe.dk

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART322Clyne, T.W. Dept. of Materials Science & Metallurgy, University of Cambridge 210Pembroke Street, Cambridge CB2 3QZ, UKtw10@cus.cam.ac.ukCoey, J.M.D. Dept. of Physics, Trinity College 92Dublin 2, Irelandjcoey@tcd.ieDavies, G.J. BT Labs. 166Martiesham Heath, Ipswich, Suffolk 175 IP5 7RE, UKgraham.j.davies@bt.comDosch, H. Max-Planck-Institut für Metallforschung 238, 243,Heisenbergstr. 1, 70569 Stuttgart, Germany 269, 289dosch@mf.mpg.deEffenberg, G. Materials Science International Services GmbH 153Postfach 80 07 49, 70507 Stuttgart, Germanyeffenberg@msiwp.comElsässer, T. Max-Born-Institut für Nichtlineare Optik u. Spektroskopie 259Max-Born-Str. 2A, 12489 Berlin, Germanyelsasser@mbi-berlin.deEtourneau, J. UPR CNRS 9048 - I.C.M.B., Université de Bordeaux I 37, 201162, Ave du Dr. Albert Schweitzer, 33608 Pessac Cedex, Francedr@icmcb.u-bordeaux.frFantozzi, G. GEMPPM - INSA de Lyon 32Bât. 502, 20 Ave. Albert Einstein, 69621 Villeurbanne Cedex, Francegilbert.fantozzi@insa-lyon.frFerro, R. Dip. di Chimica e Chimica Industriale, Università di Genova 153Via Dodecaneso 31, 16146 Genova, Italyferro@chimica.unige.itFisher, C.A.J. Computational Design Group, Japan Fine Ceramics Centre 1382-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587, Japanfisher@jfcc.or.jpFlükiger, R. DPMC, Université de Genève 9724, quai Ernest Ansermet, 1211 Genève 4, Switzerlandrene.flukiger@physics.unige.chFuertes, A. Instituto de Ciencia de Materiales de Barcelona 201Campus de la Universidad Autonoma de Barcelona, 08193 Bellaterra, Cataluña, Spainamparo@icmab.esGao, H. Max-Planck-Institut für Metallforschung 144Seestr. 92, 70174 Stuttgart, Germanyhjgao@mf.mpg.deGiordano, M. Dip. di Ingegneria dei Materialie e della Produzione, Università “Federico II” 216Piazzale Tecchio, 80, 80125 Napoli, Italy

Gumbsch, P. Max-Planck-Institut für Metallforschung 176Seestr. 92, 70174 Stuttgart, Germanypgumbsch@mf.mpg.deHalada, S. Institute of Biomaterials & Bioengineering, Tokyo Medical & Dental University 702-3-10, Kanda-surugadai, Chiyoda-ku, Tokyo 101-0062, JapanHillebrecht, U. Max-Planck-Institut für Mikrostrukturphysik 187Weinberg 2, 06120 Halle/Saale, Germanyhillebre@mpi-halle.deIannace, S. Dip. di Ingegneria dei Materialie e della Produzione, Universitá “Federico II” 216Piazzale Tecchio, 80, 80125 Napoli, ItalyAPPENDICESIwasaki, Y.Institute of Biomaterials & Bioengineering, Tokyo Medical & Dental University2-3-10, Kanda-surugadai, Chiyoda-ku, Tokyo 101-0062, Japan323Jansen, M. Max-Planck-Institut für Festkörperforschung 201Heisenbergstr.1, 70569 Stuttgart, Germanym.jansen@fkf.mpg.deKaindl, G. Institut für Experimentalphysik, FU Berlin 238Arnimallee 14, 14195 Berlin, Germanykaindl@physik.fu-berlin.deKirschner, J. Max-Planck-Institut für Mikrostrukturphysik 187Weinberg 2, 06120 Halle/Saale, Germanysekrki@mpi-halle.deKremer, K. Max-Planck-Institut für Polymerforschung 134Postfach 31 48, 55021 Mainz, Germanykremer@mpip-mainz.mpg.deKronmüller, H. Max-Planck-Institut für Metallforschung 92Heisenbergstr. 1, 70569 Stuttgart, Germanykronm@physix.mpi-stuttgart.mpg.deKunz, C. European Synchrotron Radiation Facility 238B.P. 220, 38043 Grenoble Cedex, Francevckunz@esrf.frLannoo, M. ISEM, Maison des Technologies 63Place Georges Pompidou, 83000 Toulon, Francematheron@isem.tvt.frLemstra, P. Faculteit Scheikundige Technologie, Technische Universiteit Eindhoven 48Den Dolech 2, 5612 AZ Eindhoven, The Netherlandsp.j.lemstra@tue.nlLipowsky, R. Max-Planck-Institut für Kolloid- und Grenzflächenforschung 7814424 Potsdam, Germanylipowsky@mpikg-golm.mpg.de

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART324Louër, D. Lab. de Chimie du Solide et Inorganique Moléculaire, Université de Rennes 1 238Avenue du Général Leclerc, 35042 Rennes Cedex, FranceDaniel.Louer@univ-rennes1.frLutz, P. Institut Charles Sadron, CNRS-UPR 22 2076, rue Boussingault, 67083 Strasbourg Cedex, Francelutz@ics.u-strasbg.frMittemeijer, E. Max-Planck-Institut für Metallforschung 158, 238Seestr. 92, 70174 Stuttgart, Germanye.j.mittemeijer@mf.mpg.deMöhwald, H. Max-Planck-Institut für Kolloid- und Grenzflächenforschung 18014424 Potsdam, Germanymoehwald@mpikg-golm.mpg.deMortensen, A. Dept. of Materials, EPFL 2101015 Lausanne, SwitzerlandAndreas.Mortensen@epfl.chNakabayashi, N. Institute of Biomaterials & Bioengineering, Tokyo Medical & Dental University 702-3-10, Kanda-surugadai, Chiyoda-ku, Tokyo 101-0062, Japannobuo@i-mde.tmd.ac.jpNaslain, R. Lab. des Composites Thermostructureaux , Université Bordeaux I 213Domaine Universitaire, 3, allée de La Boëtie, 33600 Pessacnaslain@lcts.u-bordeaux.frNicolais, L. Dip. di Ingegneria dei Materialie e della Produzione, Università “Federico II” 216Piazzale Tecchio, 80, 80125 Napoli, Italyass.nicolais@regione.campania.itOwens, C.R. UniStates Technology, LLC 104P.O. Box 53101, Medford, MA 02153, United StatesOwens, W.E. UniStates Technology, LLC 104P.O. Box 53101, Medford, MA 02153, United Stateswowens@unistates.comPeercy, P.S. College of Engineering, University of Wisconsin-Madison 219, 2231415 Engineering Drive, Madison-Wisconsin 53706-1691, United Statespeercy@engr.wisc.eduPloog, K.H. Paul-Drude-Institut für Festkörperelektronik 57Hausvogteiplatz 5-7, 10117 Berlin, Germanyploog@pdi-berlin.dePompe, W. Institut für Werkstoffwissenschaft, TU Dresden 11701062 Dresden, Germanypompe@tmfs.mpgfk.tu-dresden.dePond, R.C. Dept. of Materials Science and Engineering, University of Liverpool 161POB 147, Liverpool L69 3BX, United Kingdomr.c.pond@liverpool.ac.uk

Raabe, D. Max-Planck-Institut für Eisenforschung GmbH 21Postfach 14 04 44, 40074 Düsseldorf, Germanyraabe@mpie.deReynaud, P. GEMPPM - INSA de Lyon 32Bât. 502, 20 Ave. Albert Einstein, 69621 Villeurbanne Cedex, Francereynaud@gemppm.insa-lyon.frRichter, D. Forschungszentrum Jülich GmbH 243Postfach 19 13, 52425 Jülich, GermanyD.Richter@fz-juelich.deRouby, D. GEMPPM - INSA de Lyon 32Bât. 502, 20 Ave. Albert Einstein, 69621 Villeurbanne Cedex, Francerouby@gemppm.insa-lyon.frRühle, M. Max-Planck-Institut für Metallforschung 247, 253, 257Seestr. 92, 70174 Stuttgart, Germanyruehle@hrem.mpi-stuttgart.mpg.deAPPENDICES325Sahm, P.R. Giesserei-Institut, RWTH Aachen 109Intzestr. 5, 72072 Aachen, Germanysahm@gi.rwth-aachen.deSaxl, O. The Institute of Nanotechnology, University of Stirling Innovation Park 1669 The Alpha Centre, Stirling FK9 4NF, United Kingdomo.saxl@nano.org.ukScharff, P. Institut für Physik/FG Chemie, Technische Universität Ilmenau 55Postfach 10 05 65, 98684 Ilmenau, Germanyscharff@physik.tu-ilmenau.deSchlögl, R. Fritz-Haber-Institut der Max-Planck-Gesellschaft 55, 82Faradayweg 4-6, 14195 Berlin, Germanyschloegl@fhi-berlin.mpg.deSchneider, J. DESY, HASYLAB 238Notkestr. 85, 22603 Hamburg, Germanyschneider@desy.deSchüth, F. Max-Planck-Institut für Kohlenforschung 82Kaiser-Wilhelm-Platz 1, 45470 Mülheim a. d. Ruhr, Germanyschueth@mpi-muelheim.mpg.deSedel, L. Faculté de Médecine Lariboisière-St. Louis 7610, ave de Verdun, 75010 Paris, Francelaurent.sedel@lrb.ap-hop-paris.frSmith, G.D.W. Department of Materials, University of Oxford 257Parks Road, Oxford OX1 3PH, United Kingdomgeorge.smith@materials.ox.ac.uk

MAX-PLANCK-INSTITUT FÜR METALLFORSCHUNG STUTTGART326Sommer, F. Max-Planck-Institut für Metallforschung 158Seestr. 92, 70174 Stuttgart, Germanysommer@mf.mpi-stuttgart.mpg.deSpiess, H.W. Max-Planck-Institut für Polymerforschung 263Postfach 31 48, 55021 Mainz, Germanyspiess@mpip-mainz.mpg.deStoneham, A.M. Center for Materials Research, University College London 129Gower Street, London WC1E 6BT, United Kingdoma.stoneham@ucl.ac.ukTrampert, A. Paul-Drude-Institut für Festkörperelektronik 57Hausvogteiplatz 5-7, 10117 Berlin, Germanytrampert@pdi-berlin.deUrban, K. Forschungszentrum Jülich GmbH, Institut für Festkörperforschung 247Postfach 19 13, 52425 Jülich, GermanyK.Urban@fz-juelich.deVan de Voorde, M.H. Max-Planck-Institut für Metallforschung 269, 289Seestr. 92, 70174 Stuttgart, Germanyvandevoorde@mf.mpg.deVan Houtte, P. Department of Metallurgy and Materials Engineering (MTM), K.U.Leuven 183De Croylaan 2, 3001 Heverlee (Leuven), BelgiumPaul.VanHoutte@mtm.kuleuven.ac.beVan Rossum, M. Advanced Semiconductor Processing Div., IMEC 117Kapeldreef 75, 3001 Leuven, Belgiumvrossum@imec.beVon Löhneysen, M. Physikalisches Institut, Universität Karlsruhe 187Postfach 69 80, 76128 Karlsruhe, Germanyh.vL@physik.uni-karlsruhe.deWagner, T. Max-Planck-Institut für Metallforschung 196Seestr. 92, 70174 Stuttgart, Germanytwagner@mf.mpg.deWegner, G. Max-Planck-Institut für Polymerforschung 51Postfach 31 48, 55021 Mainz, Germanygerhard.wegner@mpip-mainz.mpg.deYagi, K. National Research Institute for Metals, Science and Technology Agency 2281-2-1 Sengen, Tsukuba-shi Ibaraki 305-0047, Japanyagi@nrim.go.jpZimmermann, G. Access eV 109Intzestr. 5, 72072 Aachen, Germanygerhardz@big1.gi.rwth-aachen.de