Wüest M. 51 Wykes M. 82 Yamaguchi M. 17 Ybarra G. 129 Yubero F ...
Wüest M. 51 Wykes M. 82 Yamaguchi M. 17 Ybarra G. 129 Yubero F ...
Wüest M. 51 Wykes M. 82 Yamaguchi M. 17 Ybarra G. 129 Yubero F ...
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<strong>Wüest</strong> M. <strong>51</strong><br />
<strong>Wykes</strong> M. <strong>82</strong><br />
<strong>Yamaguchi</strong> M. <strong>17</strong><br />
<strong>Ybarra</strong> G. <strong>129</strong><br />
<strong>Yubero</strong> F. 20, 23<br />
Yurasova V.E. 15<br />
Zelaya-Angel O. <strong>17</strong>, 127, 128<br />
Zykova E.Yu. 15<br />
149
Rusu G.I. 131<br />
Rusu M. 126, 131<br />
Ryzhov Yu.A. 15<br />
Sacedón J.L. 25, 72<br />
Sánchez O. 100, 103<br />
Sánchez-López J.C. 101<br />
Sanguino P. 116<br />
Schwarz R. 116<br />
Shakarban I.I. 15<br />
Silva R.F. 9, 99-140<br />
Simao R.A. 99<br />
Smail H. 46<br />
Solis J. 78<br />
Soriano L. 10<br />
Stupnik A. 88<br />
Tabarés F.L. 30, 33<br />
Tafalla D. 33<br />
Tavares C.J. 21, 1<strong>17</strong><br />
Teba, D. 61<br />
Teixeira M.R. 90<br />
Teixeira V. 21, 1<strong>17</strong><br />
Teodoro O.M.N.D. 48, 70, 89, 91, 116, 120<br />
Tesar J. 69<br />
Tessema G. 122<br />
Tikhomirov A.V. 31<br />
Tilford Ch. R. 6<br />
Torres-Kauffman J. 128<br />
Trigo J.F. 10, 61<br />
Valencia-Alvarado R. 124<br />
Vanhulsel A. 94<br />
Vaz F. 75, 98<br />
Vázquez E. 121<br />
Vázquez L. 37<br />
Verheyde B. 94<br />
Verhoeven J. 56<br />
Vicar M. 69<br />
Vidal-Larramendi J. 127<br />
Vieira P. 93<br />
Vigil-Galán O. 127<br />
Vila M. 24,138<br />
Vilajuana T. 64<br />
Villuendas F. 60<br />
Völklein F. 106<br />
Wemans A. 42,45,48<br />
Wilhelm M. 116<br />
148
Oliveira F. J. 140<br />
Orts M.J. 76<br />
Otal P. 71<br />
Ouchabane M. 125<br />
Paiva A.C.S. 95<br />
Palacín S. 10<br />
Palomino-Merino R. 128<br />
Pardo A. 113<br />
Parreira N.M.G. 16, 102<br />
Patscheider J. 14<br />
Pearce R.J.H. <strong>82</strong><br />
Peksa L. 69<br />
Peña-Eguiluz R. 124<br />
Pereira P.J.S. 90<br />
Pérez-Martín A.M.C. 22<br />
Piechowiak M. 44<br />
Pinto R.M. 92<br />
Polcar T. 16, 96<br />
Portillo-Moreno O. <strong>17</strong>, 128<br />
Powell S. 58<br />
Prazak D. 69<br />
Preda I. 10<br />
Prepelita P. 131<br />
Prieto C. 26, 138<br />
Raboso D. 130<br />
Ramos A.R. 21<br />
Ramos-Barrado J.R. 47<br />
Rayon E. 11<br />
Rebouta L. 98<br />
Reid R.J. 50<br />
Reis E.M.C.C. 89<br />
Repa P. 69<br />
Ribera J. 77<br />
Rico M. 104<br />
Rico V. 23<br />
Rico J. 20<br />
Rios P. 113<br />
Rodríguez R.J. 36, 38, 104, 112<br />
Rodríguez-Cañas E. 25<br />
Román E. 94, 109, 130<br />
Romero J. 13<br />
Rueda F. 121<br />
Ruiz A. 130<br />
Ruiz S. 53<br />
Rusu G.G. 126<br />
147
Leinen D. 47<br />
Leisch M. 88<br />
Lévy L. 113<br />
López-Callejas R. 124<br />
López-Cartes C. 101<br />
López-Ibáñez R. 47<br />
Lousa A. 13, 41<br />
Lozada-Morales R. <strong>17</strong>, 128<br />
Lozano P. 130<br />
Lucas F. 76<br />
Maneira M.J.P. 42, 45, 48, 90<br />
Marco J.M. 59<br />
Mardare D. 119<br />
Mari D. 67<br />
Marín M. 100<br />
Marques H.P. 48, 70, 91<br />
Marques S.M. 21, 1<strong>17</strong><br />
Martín F. 47<br />
Martínez L. 94<br />
Martínez R. 36, 38, 104<br />
Martínez-Martínez D. 101<br />
Matilla C. 32, 53<br />
Matveeva E. 11, 63<br />
Medina N. 53<br />
Meier A. 106<br />
Mejia J.P. 41<br />
Mendez J. 94<br />
Mercado-Cabrera A. 124<br />
Miralles LL. 107<br />
Mohammedi L. 137<br />
Moina C. <strong>129</strong><br />
Montero I. 112, 113, 130<br />
Mosunov A.S. 15<br />
Moutinho A.M.C. 70, 91, 120<br />
Moya J.S. 72<br />
Muñoz-Castro A.E. 124<br />
Narayanan K.L. <strong>17</strong><br />
Neto M.A. 9<br />
Nevshupa, R. 109<br />
Nunes Y. 42, 45, 48<br />
Nunzi J.M. 118<br />
Ochando I.M. 26, 138<br />
Orgaz F. 79<br />
Oliva A.I. 25<br />
Oliveira F. 24<br />
146
Gabouze N. 125<br />
Galán L. 112, 113, 130<br />
García G. 36<br />
García J.A. 36, 38, 79, 104<br />
García M. 130<br />
García-López F.J. 26<br />
García-Luis A. 12, <strong>129</strong>, 136<br />
García-Rocha M. 128<br />
Garg D. 20<br />
Gheriani R. 133, 137<br />
Gikal B.N. 31<br />
Girtan M. 118, 126<br />
Godoy-Cabrera O.G. 124<br />
Gomes J.R. 99<br />
Gomes M.J.M. 44<br />
Gómez-Aleixandre C. 37<br />
González D. 12, <strong>129</strong>, 136<br />
González R. 114<br />
González-Elipe A.R. 20, 23, 43, 62<br />
Gordo P.R. 42, 45<br />
Gracia F. 62<br />
Gronych T. 69<br />
Guerra M. 95<br />
Gulbekian G.G. 31<br />
Gutierrez A. 10<br />
Gutiérrez M.T. 27<br />
Hadjar Y. 135-139<br />
Halimi R. 133, 134, 135, 137-139<br />
Harkati C. 134<br />
Herrasti P. 121<br />
Hidalgo J.M. 52, 68<br />
Högberg H. 86<br />
Huttel Y. 94<br />
Jacobs R. 94<br />
Jensen H.S. 108<br />
Jiménez-Rioboó R.J. 26<br />
Jiménez-Rodríguez J.J. 22<br />
Jiménez-Sáez J.C. 22<br />
Jousten K. 29<br />
Khalfallah F, 139<br />
Khodorov A. 44<br />
Kreissing U. 98<br />
Kunst M. 116<br />
Lara A. 61<br />
Legras J-C. 71<br />
145
Cavaleiro A. 16, 39, 79, 96, 102<br />
Chigiatto P. 81<br />
Coelho B. 24<br />
Colera I. 114<br />
Colligon J.S. 15<br />
Contreras-Puente G. 127<br />
Corengia P. 136, <strong>129</strong><br />
Costa F.M. 9<br />
Costa M.L. 89, 92, 93<br />
Cotrino J. 20, 43<br />
Cristo P.M.S. 93<br />
Dabos-Seignon S. 118<br />
Daniel B. 58<br />
Day Ch. 108<br />
de la Piedad-Beneitez A. 124<br />
de la Rosa-Vázquez J. 124<br />
de las Heras E. <strong>129</strong><br />
de Segovia J.L. 52, 68, 109, 112, 113, 114<br />
Devia A. 41<br />
Dias A.A. 89,92, 93<br />
Díaz B. 100<br />
Díaz M. 72<br />
Díaz R. 121<br />
Duarte A. 24<br />
Dumitru L. 119<br />
Van Eesbeek M. 113<br />
Elovikov S.S. 15<br />
Escobar Galindo R. 11, 26<br />
Escrivao M.L. 90<br />
Espinós J.P. 20, 23<br />
Esteve J. 41<br />
Evaristo M. 96<br />
Falcony C. 103<br />
Fazio G. 83<br />
Ferreira Q. 48<br />
Fernandes A.J. 21, 1<strong>17</strong><br />
Fernandes A.J.S. 9, 24-140<br />
Fernández A. 101<br />
Ferrerira J.A. 30, 33<br />
Ferreira R. 19<br />
Fonseca A.P. 70<br />
Freitas P.P. 19<br />
Freitas S. 19<br />
Frutos F. 23<br />
Fuentes G.G. 38, 112<br />
144
AUTHOR’S INDEX<br />
Aouabdia Y. 46<br />
Ababou A. 125<br />
Abb el Lefdil M. 121<br />
Abdel Hamid B. 46<br />
Achete C.A. 99<br />
Acuña R. 61<br />
Afonso C.N. 65<br />
Agote I. 136<br />
Aguilar-Hernández J. 127<br />
Aissani L. 134<br />
Ait-Hamouda K. 125<br />
Al-Dmour E. 107<br />
Albella J.M. 11, 37, 79,103<br />
Alberdi A. 76, 100<br />
Almeida F. A. 140<br />
Álvarez L. 94<br />
Alves E. 21, 98<br />
Amaral M. S. 140<br />
Andrés M. 27<br />
Araiza J.J. 103<br />
Arias-Carbajal A. 127<br />
Auger M.A. 103<br />
Aznárez J.A. 25<br />
Baban C. 131<br />
Barocio S.R. 124<br />
Barradas N.P. 98<br />
Barranco A. 43, 62<br />
Belda A. 76<br />
Bellido-González V. 58<br />
Bergoglio M. 67<br />
Boineau F. 71<br />
Borrás A. 43, 62<br />
Brizuela M. 12, <strong>129</strong>, 136<br />
Buijnsters J.G. 37<br />
Cáceres D. 26, 114<br />
Calcatelli A. 67<br />
Camargao S.S. 99<br />
Camero M. 37<br />
Canário A.R. 91, 120<br />
Carda J. 77<br />
Carneiro J.O. 21, 1<strong>17</strong><br />
Carrapichano J.M. 99<br />
Carvalho P. 75<br />
143
142
AUTHORS’S INDEX<br />
141
JUNE 28 WEDNESDAY AFTERNOON<br />
JS2-WeA-P.8 NANO TO MICROMETRIC HFCVD DIAMOND ADHESION STRENGTH<br />
TO Si 3 N 4 . F.A. Almeida, M.S. Amaral, F.J. Oliveira, R.F. Silva. Dept. of Ceramics and Glass Engineering,<br />
CICECO, Univ. of Aveiro, 3810-193 Aveiro, Portugal. A.J.S. Fernandes. Dept. of Physics,<br />
Univ. of Aveiro, 3810-193 Aveiro, Portugal<br />
CVD diamond coated materials possess unique properties (hardness, thermal conductivity, chemical<br />
inertness) that demand their selection as components of tribosystems working under mechanical<br />
and/or chemical severe conditions. Examples of such applications are cutting tools for highly abrasive<br />
materials and mechanical seals for pumping of corrosive liquids. Furthermore, an increasing interesting<br />
field of application is biomedicine, namely cirurgical tools and coatings for articular implants,<br />
where diamond’s biocompatibility is an essential issue. However, the high surface roughness of conventional<br />
microcrystalline CVD diamond is a major problem when considering such purposes, as the<br />
sliding contact of diamond asperities may increase stress and temperature levels, leading to an increasing<br />
wear rate. To overcome this drawback, today’s goal is the development of diamond crystals with<br />
very small grains of nanometric size by adequate CVD parameters, avoiding the typical columnar<br />
growth of microcrystalline diamond structures. When considering tribological and mechanical applications,<br />
adhesion of the film to the substrate determines the success of the component in service. In this<br />
study, distinct diamond coatings on silicon nitride ceramic substrates with different crystallite sizes<br />
were investigated: i) nanocrystalline diamond (~25 nm); ii) submicrometric diamond (~ 40 nm); and<br />
iii) conventional micrometric size (~10 μm). The coatings, with thickness of about 40 μm, were grown<br />
by hot filament CVD technique. The effect of these diamond structures on adhesion strength to the ceramic<br />
substrate will be evaluated by Brale tip indentation and correlated with their Raman signature.<br />
140
JUNE 28 WEDNESDAY AFTERNOON<br />
JS2-WeA-P.7 STUDY OF SOME PROPERTIES OF HARD TUNGSTEN CARBIDE<br />
COATINGS. F. Khalfallah, Y. Hadjar, R. Halimi. Laboratoire des Couches Minces et Interfaces,<br />
Département de Physique, Faculté des Sciences, Université Mentouri, 25000 Constantine, Algérie.<br />
In this work, we have studied the properties of hard coatings of tungsten carbides. The samples are<br />
thin layers of Tungsten deposited at 500°C on two types of steel (containing 1 and 0,7% wt. carbon)<br />
substrates. The samples were then heat treated in vacuum, at various temperatures (500-1000°C) and<br />
during different times.<br />
The formation of tungsten carbides, the evolution of the microstructure and the morphology of the surface<br />
of samples were followed by X-ray diffraction (XRD) and scanning electron microscopy (SEM).<br />
The measurements of micro-hardness were carried out by Vickers tests.<br />
Thermal annealing produces reactions and some other structural changes in the tungsten layers which<br />
depend on the carbon content in substrate.<br />
It is established that the formation of tungsten carbides occurs above annealing at 800°C. The reaction<br />
is more rapid on substrate containing 1%C. The mono-carbide WC forms after annealing at 1000°C.<br />
The hardness of coatings increases continuously from 400 to 1200 Kg/mm² as the temperature of annealing<br />
increases from 500 to 900°C. The samples rich on carbon show higher hardness.<br />
Key words: hard coatings, tungsten, carbides, thin films.<br />
Presenting author: F. KHALFALLAH<br />
Contacts and email: Tel/Fax: 213 31 61 47 11; fa_fares@yahoo.fr<br />
Presentation type: Poster<br />
139
JUNE 28 WEDNESDAY AFTERNOON<br />
JS2-WeA-P.6 OPTICAL AND STRUCTURAL STUDY OF EB-PVD ZrO 2 THIN FILMS.I.<br />
M. Ochando, M. Vila and C. Prieto. Instituto de Ciencia de Materiales de Madrid, Consejo Superior<br />
de Investigaciones Científicas. Cantoblanco, 28049 – MADRID, Spain.<br />
Zirconium oxide is a widely used material because of its heat resistance, low thermal conductivity,<br />
high refractive index and high transparency in the visible and near infrared region, very high chemical<br />
inertness and high laser damage threshold. Due to these properties, its applications can be found in<br />
very different aspects of technology. For instance, zirconia has been applied as thermal barrier coating<br />
(1), optical filters, laser mirrors(2), buffer layer for high T C superconductor on Si (3), high temperature<br />
oxygen separation (4), oxygen sensors(5), and solid oxide fuel cells(6).<br />
Films of zirconia can be prepared by different techniques. Typically, thin films prepared by sputtering<br />
are used for gate dielectric in microelectronics applications and zirconia films prepared by electron<br />
beam physical vapour deposition (EB-PVD) are candidates for advanced thermal barrier coatings<br />
(TBC) for the new generation of land-based gas turbines as well as for optical applications. In the interest<br />
host materials with a high luminescent efficiency and superior stabilization, tetragonal ZrO2 is<br />
an attractive material due to the refractive index, electrical, chemical and mechanical characteristics.<br />
ZrO 2 thin films prepared on Si(100) substrates by electron beam physical vapour deposition (EB-<br />
PVD) are investigated by X-ray diffraction and optical absorption spectroscopy. Results show tetragonal<br />
stabilized phases of zirconium oxide independently of the yttria addition in the starting material. In<br />
this work, it is reported the variation of the crystallite size as a function of the deposition rate, showing<br />
that crystallites are in the nanometric range and that a remarkable crystallite size increase is observable<br />
for thin films prepared at low deposition rates.<br />
In addition, it is presented the optical absorption spectroscopy characterization in order to determine<br />
the refractive index; the obtained values does not depend on the deposition rate being in agreement<br />
with the bulk ones. It is shown EB-PVD prepared samples have good performance for optical and protective<br />
coatings.<br />
2<br />
3<br />
4<br />
5<br />
6<br />
S.M. Meier, D.K. Gupta, J Eng. Gas Turbines Power Trans. ASME 116 (1994) 250.<br />
W.H. Lowdermilk, D. Milam, F. Rainer, Thin Solid Films 73 (1980) 155.<br />
D.K. Fork, D.B. Fenner, G.A.N. Connell, J.M. Phillips, T.H. Geballe, Appl. Phys. Lett. 57 (1990) 1137.<br />
J. Han, Y.Zeng, G. Xomeritakis, Y.S. Lin, Solid State Ionics 98 (1997) 63.<br />
M. Sayer , K.Sreenivas, Science 247 (1990) 1056.<br />
N.Q. Minh, J. Am. Ceram. Soc. 76 (1993) 563.<br />
138
JUNE 28 WEDNESDAY AFTERNOON<br />
JS2-WeA-P.5 ELABORATION AND CHARACTERIZATION OF THIN TITANIUM<br />
COATINGS ON HIGH CARBON STEEL SUBSTRATES. L. Mohammedi. Laboratory of Materials<br />
Physic. University of Ouargla – 30 000 – Algeria. R. Gheriani. Laboratory of Materials Physic.<br />
University of Ouargla – 30 000 – Algeria. R. Halimi. Laboratoire Couches Minces et Interfaces, Campus<br />
Chaâb Erssas, Université Mentouri de Constantine - 25 000 Constantine – Algérie.<br />
In this work we have elaborated, by cathodic sputtering, thin titanium coatings on steel substrates containing<br />
≈ 2% Wt of carbon. The so prepared samples are submitted to various thermal anneals in vacuum<br />
between 400°C and 1000°C, and then characterized structurally and mechanically by X-ray diffraction<br />
(XRD), scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and hardness<br />
tests. The analysis of samples showed the formation and the growth of titanium carbide above<br />
400°C. It is established that carbon, iron and titanium atoms interdiffuse intensively, and form a diffusion<br />
zone which is, roughly, homogeneous and essentially constituted from titanium carbide. This new<br />
layer presents a good performances (for example, at 900°C, the value of microhardness is H v = 3200<br />
kg mm -2 , which is larger than that of bulk TiC H v = 3000 kg mm -2 ).<br />
Key words: thin films, hard coatings, carbide, diffusion, titanium<br />
137
JUNE 28 WEDNESDAY AFTERNOON<br />
ETCHC-WeA-P.4 DEPOSITION OF Ti-B-Al-N COATINGS BY MAGNETRON SPUT-<br />
TERING OF COMPOSITE SHS TARGETS. A. García-Luis * , M. Brizuela, P. Corengia, D. González,<br />
I. Agote. INASMET-Tecnalia, Paseo de Mikeletegi 2, 20009 San Sebastián, Spain<br />
The synthesis of complex multicomponent coatings by magnetron sputtering usually involves the use<br />
of several single-material targets, multi-material targets or composite targets. There are several methods<br />
of producing composite targets, for example, hot pressing, hot extrusion, hot isostatic pressing or<br />
plasma spraying of the component materials of the target. However, each of these methods has some<br />
limitations regarding purity, porosity, uniformity of the microstructure or manufacturing costs. Self-<br />
Propagating High-temperature Synthesis (SHS) is an energy-efficient alternative method which uses<br />
exothermic reactions to synthesize compact and pure inorganic materials, including intermetallics, ceramics<br />
and ceramic composites.<br />
In this work, Ti/TiB 2 (5 % Al) composite targets produced by the SHS technique has been used to deposit<br />
PVD coatings based in Ti-B-Al-N compositions. The process optimization has included the<br />
study of the experimental parameters (cathode power, gas flows and heating on the chamber) on the<br />
coating properties. Mechanical properties have been evaluated by dynamic ultramicroindentation<br />
techniques and scratch testing, while tribological tests have been carried out against ball bearing steel<br />
by the pin-on-disk method.<br />
Ultramicrohardness values up to 36 GPa, together with a very good elastic behaviour (elastic work 92<br />
%) have been obtained for some selected Ti-B-Al-N coatings. The adhesion of these coatings to steel<br />
substrates has been satisfactory, with values of critical load in the scratch test higher than 55 N. Finally,<br />
the wear tests confirm the good tribological properties of these coatings, giving no measurable<br />
wear of the coated disk after the pin-on-disk test.<br />
* Corresponding author: Tel: +34 943 003700; fax: +34 943 003800, e-mail: agarcia@inasmet.es<br />
136
JUNE 28 WEDNESDAY AFTERNOON<br />
JS2-WeA-P3 CARBIDES FORMATION IN TANTALUM THIN LAYERS DEPOS-<br />
ITED ON STEEL SUBSTRATES. Y. Hadjar. Institut de Tronc Commun Sciences Exactes et<br />
Technologie, Université de Batna, Algérie, R. Halimi, Laboratoire Couches Minces et Interfaces,<br />
Université Mentouri, 25000 Constantine, Algérie.<br />
In the present work we are intending to elaborate and to study thin film coating of tantalum carbides<br />
on steel substrates. The procedure used in order to prepare the samples consist on depositing, by<br />
electron gun evaporation, a thin film (4µm thickness) of tantalum on steel substrates containing 1<br />
%wt. of carbon, then, annealing the system (substrate/coating) in vacuum at a temperature at which<br />
the carbon of the substrate may diffuse into the Ta metallic film. This fact leads to the formation of<br />
tantalum carbides. The effects of the annealing on the kinetic of tantalum carbides formation and<br />
morphology have been investigated using X- ray diffraction (XRD), secondary ion mass spectroscopy<br />
(SIMS) and scanning electron microscopy (SEM). The mechanical characterization was performed<br />
by measuring microhardness and adhesion. It is found that at annealing up to 800°C the<br />
compounds Ta 2 C and TaC are formed. During the subsequent heat treatment from 900°C to 1100°C<br />
the final TaC phase grows at the expense of the Ta2C phase. Moreover, the microhardness and adhesion<br />
of the films increase significantly with increasing annealing temperature. At a given temperature,<br />
the microhardness increases, with the rise of the annealing time, to reach a maximum and then<br />
decreases. The final coating layer has a golden color and presents a columnar structure. The formation<br />
mechanisms are discussed.<br />
Key words: hard coatings, tantalum carbides, thin films, diffusion.<br />
Presenting author: R. HALIMI<br />
E-mail: rachid_halimi@yahoo.fr<br />
Presentation type: Poster<br />
135
JUNE 28 WEDNESDAY AFTERNOON<br />
JS2-WeA-P.2 SYNTHESIS AND CHARACTERIZATION OF THIN HARD COAT-<br />
INGS OF CHROMIUM CARBIDES. L. Aissani. Département de Physique, Centre universitaire<br />
de Khenchela, Algérie. C. Harkati, and R. Halimi. Laboratoire Couches Minces et Interfaces, Département<br />
de Physique, Faculté des Sciences, Université Mentouri, 25000 Constantine, Algérie.<br />
Hard chromium carbide coatings were elaborated by depositing a chromium layer ( 3μm or 1 μm<br />
thickness ), using the physical vapour deposition technique of magnetron sputtering, on carbon steel<br />
substrates and, subsequently, annealing the system in vacuum at temperatures from 200°C to<br />
1200°C. Structural characterization was assessed using scanning electron microscopy and X-ray diffraction.<br />
Some mechanical properties such as micro and nano-hardness and residual stresses were<br />
studied. It was found that the binary carbides Cr 7 C 3 , and Cr 23 C 6 appear at 700°C and 900°C respectively.<br />
The Cr 7 C 3 compound transforms then at 1000°C into ternary carbide (Cr,Fe) 7 C 3 . It was<br />
showed that the micro and nano-hardness increase with the rising of annealing temperature until<br />
reaching a maximum value and then decreases. The increase of the hardness is associated to the<br />
chromium carbides formation, which are harder. However, its decrease is due to the iron atoms diffusion<br />
into the coating layer. Thicker Chromium coatings present a better adhesive properties. It is,<br />
also, observed that the compressive residual stresses in coating (σ ϕ = -734 MPa at 900°C) become<br />
tensile at 1000°C (σ ϕ = 127 MPa).<br />
Keywords: Chromium, coating, carbides, thin films<br />
Presenting author: L. AISSANI<br />
E-mail: lindaaissani2004@yahoo.fr<br />
Presentation type: Poster<br />
134
JUNE 28 WEDNESDAY AFTERNOON<br />
JS2-WeA-P.1 IMPROVEMENT OF MECHANICAL PROPERTIES OF STEEL<br />
SUBSTRATES SURFACE BY DEPOSITION OF THIN TITANIUM FILMS OBTAINED BY<br />
MAGNETRON SPUTTERING METHOD. R. Gheriani. Physical laboratory of Materials, University<br />
of Ouargla , 30.000- Algeria. R. Halimi. Unity of research, Materials and applications, University<br />
of Constantine, 25.000 – Algeria.<br />
Titanium carbides are well known materials with great scientific and technological interest. The applications<br />
of these materials take advantage of the fact that they are very hard, refractory and that<br />
they have metallic properties.<br />
In this work, We have studied the influence of the heat treatment temperatures ( 400-1000°C) on the<br />
interaction between the titanium thin films and steel substrates. Steel substrates, 100C6 type (AF-<br />
NOR norms), containing approximately 1 wt % of carbon, were coated at 200°C with titanium thin<br />
films by magnetron sputtering.<br />
The samples were characterized by X ray diffraction (XRD), Auger electron spectroscopy (AES) and<br />
scanning electron microscopy (SEM). Vikers micro-hardness measurements carried out on the annealed<br />
samples showed that the micro-hardness increases with annealing temperature, reaches a<br />
maximum (3500 kg/mm 2 ), then decreases progressively. The growth of micro-hardness is due to the<br />
diffusion of the carbon, and to the formation of titanium carbide. However, the decrease of microhardness<br />
is associated to the diffusion of iron and the formation of iron oxide (Fe 2 O 3 ). At higher<br />
temperatures, we note the formation of titanium oxide (TiO 2 ).<br />
133
JS2 POSTERS<br />
132
JUNE 28 WEDNESDAY AFTERNOON<br />
JS1-WeA-P.8 ON THE INFLUENCE OF TE EXCESS ON THE OPTICAL PROP-<br />
ERTIES OF VACUUM EVAPORATED ZNTE THIN FILMS. P. Prepeliţă, M.Rusu, C.Baban,<br />
G.I.Rusu. Faculty of Physics “Al. I. Cuza” University, B-dul Carol I, No.11, Iasi, Romania. (e-mail:<br />
prepelita@stoner.phys.uaic.ro)<br />
ZnTe thin films are intensively studied due to their interesting properties such as high transmission<br />
coefficient, large energy bandgap, low electrical resistivity, etc. An important factor that influences<br />
the properties of these films is the deviation from their stoichiometric composition. In present paper,<br />
the influence of tellurium excess on the optical properties of evaporated ZnTe thin films is investigated.<br />
The studied films (d = 0.700 µm - 1.300 µm) were deposited onto unheated glass substrates by<br />
evaporation under vacuum of ZnTe powder at source temperature ranged between 900 K and 1200<br />
K. The structural analysis of the films was performed by XRD and AFM techniques. The optical parameters<br />
(refractive index and absorption coefficient) both for as deposited and heat treated samples<br />
were determined from transmission spectra in the spectral range 340 nm - 1400 nm.<br />
It was found that the studied films present a polycrystalline zinc blende structure with preferential<br />
orientation of (111) planes parallel to the substrate. An excess of tellurium atoms which aggregate in<br />
crystallite form during film annealing was observed. This Te excess determines a significant increase<br />
of the absorption coefficient near the fundamental absorption edge and of refractive index in the infrared<br />
domain. Depending on Te content, the optical bandgap energy, E g , calculated from the absorption<br />
spectra, ranged between 1.9 eV and 2.4 eV.<br />
The results are discussed in correlation with film structure and the impurity levels introduced by the<br />
Te excess.<br />
131
JUNE 28 WEDNESDAY AFTERNOON<br />
JS1-WeA-P.7 UHV REACTIVE EVAPORATION GROWTH OF TITANIUM NI-<br />
TRIDE THIN FILMS, LOOKING FOR MULTIPACTOR EFFECT SUPPRESSION IN<br />
SPACE APPLICATIONS. Ana Ruiz and Elisa Román. Instituto de Ciencia de Materiales de Madrid.<br />
Consejo Superior de Investigaciones Científicas. Cantoblanco. E-28049-Madrid. Spain Pilar<br />
Lozano*, Mariano García and Luis Galán. Departamento de Física Aplicada. Universidad Autónoma<br />
de Madrid.Cantoblanco. E-28049 Madrid. Spain. Isabel Montero. Instituto de Ciencia de Materiales<br />
de Madrid. Consejo Superior de Investigaciones Científicas. Cantoblanco. E-28049-Madrid. Spain.<br />
David Raboso. ESA/ESTEC. Keplerlaan, 1. 2200 AG Noordwijk. The Netherlands.<br />
A low secondary electron emission yield which remains stable after exposure to ambient, as well as a<br />
good electrical conductivity, have proved to be basic criteria for selecting a reliable coating in RF<br />
components for space applications, in order to reduce the multipactor effect. Although titanium nitride<br />
is among the most appropriate materials, its actual performance is very much dependent on the<br />
deposition conditions. Standard deposition techniques used for TiN thin films or coatings often produce<br />
layers that are far from optimal, specially concerning secondary emission yield and its stability<br />
when exposed to air.<br />
In this work, an ultra-high vacuum reactive evaporation procedure has been tested and optimized for<br />
the growth of TiN thin films, throwing very good results both in composition of the TiN layers and<br />
SEY values and performance. Sublimation of Ti filaments is carried out in a ultra-high vacuum<br />
chamber in which a controlled leak of high purity N 2 is placed close to the substrate surface, thus<br />
maintaining the overall pressure in the high vacuum range and preventing nitridation of the Ti filaments.<br />
Detailed description of the growth procedure, substrate preparation and deposition protocol<br />
will be described with special emphasis on the relevant growth parameters and practical hints and<br />
how to achieve them. We present a study of the samples grown, such as stoichiometry and composition<br />
obtained by means of XPS and AES, and secondary electron emission measurements versus<br />
time in the scale of several months. The results obtained show that the deposition technique throws<br />
the best results towards the multipactor effect suppression.<br />
*present address: Instituto Universitario de Investigación en Nanociencia de Aragón. Universidad de<br />
Zaragoza.<br />
Edificio Interfacultativo II. c/ Pedro Cerbuna,12.E-50009 Zaragoza (Spain)<br />
130
JUNE 28 WEDNESDAY AFTERNOON<br />
JS1-WeA-P.6 DC-PULSED PLASMA NITRIDING (DCPPN) OF STANLESS STEEL:<br />
MICROSTRUCTURE, CORROSION A WEAR BEHAVIOUR. P. Corengia 1 , E. De Las<br />
Heras 2 , M. Brizuela 1 , D. González 1 , A. García-Luis 1 , G. <strong>Ybarra</strong> 2 , C. Moina 2 . 1 Fundación INASMET-<br />
Tecnalia, Paseo de Mikeletegi 2, 20009 San Sebastián, Spain. 2 Instituto Nacional de Tecnología Industrial,<br />
Av. Gral. Paz 5445, C.C. 157, (B1650 WAB) San Martín, Argentina.<br />
Stainless steels are usually employed as engineering materials due to high corrosion resistance.<br />
However, low wear resistance and poor tribological behaviour limit their use in some industrial applications.<br />
Therefore, there is an increasing interest in improving surface properties through plasma<br />
assisted treatments, notably ion nitriding. Although stainless steels can be nitrided with the consequential<br />
increase in surface hardness, which improves their tribological performance, this is accompanied<br />
by a loss of corrosion resistance of the nitrided case. Nitriding of stainless steels leads to a<br />
depletion of chromium content in the matrix, thus reducing the corrosion resistance of the nitrided<br />
layer.<br />
In the present work, industrial-scale DC-pulsed plasma nitriding for 20 h at 673K was used to improve<br />
the surface properties of both martensitic (AISI 410) and austenitic (AISI 316L) stainless<br />
steels. The effect of nitriding on structural and mechanical properties of the nitrided layer was investigated<br />
by optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and<br />
microhardness.<br />
The tribological behaviour was studied and compared to the behaviour of the same steel in asreceived<br />
condition. The wear resistance was investigated using an Amsler-disc-machine, employing<br />
a dry combined contact of rolling–sliding with three different applied loads. The wear mechanisms<br />
involved during the test of unnitrided and plasma nitrided steels were investigated by microscopic<br />
observation of the surfaces, the corresponding cross-sections and the produced wear debris. In addition<br />
microhardness profiles were done in order to evaluate the work hardening effect during the wear<br />
process. Electrochemical experiments in 3% NaCl solution were carried out to characterize the corrosion<br />
behaviour of unnitrided and nitrided stainless steels.<br />
Analysis and discussion of the tribological results show that plasma nitriding improves the wear resistance<br />
of the surface on stainless steels and the main wear mechanism appears to be delamination.<br />
Consequences on the load bearing capacity are discussed.<br />
The modified layers of the nitrided AISI 316L steel were composed of “expanded austenite”, while<br />
the nitrided AISI 410 samples were characterized by the presence of “expanded ferrite”, CrN and<br />
Fe 4 N.<br />
The DCPPN samples of both AISI 316L and AISI 410 revealed a surface hardness above 1000 HV<br />
and a sharp interface between the case (nitrided layer) and the core (matrix).<br />
Results of electrochemical measurements of unnitrided and DCPPN specimens were analysed and<br />
related to the microstructural characteristics of the nitrided case.<br />
Corresponding author: Tel: +34 943 003700; fax: +34 943 003800, e-mail:<br />
pablo.corengia@inasmet.es<br />
<strong>129</strong>
JUNE 28 WEDNESDAY AFTERNOON<br />
JS1-WeA-P.5 PHOTOLUMINESCENCE OF RHODAMINE 6G DOPED AMOR-<br />
PHOUS TIO 2 THIN FILMS GROWN BY SOL-GEL. R. Palomino-Merino 1 , J. Torres-<br />
Kauffman 1 , R. Lozada-Morales 1 , and O. Portillo-Moreno 2 , Benemérita Universidad. Autónoma de<br />
Puebla. 1 Posgrado en Optoelectrónica, Facultad de Ciencias Físico-Matemáticas. 2 Facultad de Ciencias<br />
Químicas. México. M. García-Rocha, and O. Zelaya-Angel. Department of Physics. Centro de<br />
Investigacion y de Estudios Avanzados del IPN. P.O. Box 14-740, Mexico 07360 D.F.<br />
Rhodamine 6G doped amorphous titania thin films were prepared by the sol-gel technique. The films<br />
were grown at room temperature and supported on silica-glass substrates which were previously<br />
chemically activated. Photoluminescence (PL) spectra were registered at room temperature by using<br />
as photoexcitation the 325 nm He-Cd line. The PL versus the photon energy emission curves peak at<br />
around 3.2 eV, which open the possible application of this material for solid state UV laser devices<br />
fabrication.<br />
128
JUNE 28 WEDNESDAY AFTERNOON<br />
JS1-WeA-P.4 PHOTOLUMINESCENCE AND BAND-SPLITTING IN CDS THIN<br />
FILMS, INFLUENCE OF CDCL 2 AND THERMAL ANNEALING. O. Vigil-Galán, G.<br />
Contreras-Puente, and J. Aguilar-Hernández. Escuela Superior de Física y Matemáticas, Instituto Politécnico<br />
Nacional, México 07738 D.F. J. Vidal-Larramendi, and A. Arias-Carbajal. Univ. de la Habana,<br />
43100, La Habana, Cuba. O. Zelaya-Angel. Departamento de Física, CINVESTAV-IPN, P.O.<br />
Box 14-740, México 07360 D. F.<br />
CdS thin films were deposited on conducting glass substrates by three different techniques: (a)<br />
chemical bath deposition (CBD), (b) close spaced vapor transport (CSVT), and (c) laser ablation<br />
(LA). As-grown and coated with CdCl 2 CdS-samples were thermal treated (TT) in Ar. From optical<br />
absorption measurements the valence band splitting in cubic and hexagonal layers are observed (in<br />
CBD and CSVT films). In the case of CdS films grown by CSVT the hexagonal wurtzite (W) crystalline<br />
phase is observed in as-grown and TT samples, while using CBD as-grown and annealed CdS<br />
films are cubic zincblende (ZB). For LA-CdS samples no band splitting was observed in both asgrown<br />
and annealed samples, these two types of LA-CdS layers have W as crystalline phase. Band<br />
splitting is characterized for the variation of the energy band gap (E g ) shift (ΔE g ) due to the spin-orbit<br />
*<br />
*<br />
interaction with ΔE g = 0.069 eV, where ΔE g → Δ E g<br />
when ZB → W, with Δ E g<br />
= 0.081 eV, the<br />
change is owing to the reordering of splitting levels because of the addition of the crystal field interaction.<br />
The evolution of the crystalline quality and the ΔE g change in the three kinds of grown films,<br />
beside optical absorption measurements, was studied from photoluminescence spectra<br />
127
JUNE 28 WEDNESDAY AFTERNOON<br />
JS1-WeA-P.3 OPTICAL CHARACTERIZATION OF VACUUM EVAPORATED<br />
CdZnTe THIN FILMS DEPOSITED BY STACKED LAYER METHOD. G.G. Rusu, M. Rusu,<br />
M. Girtan. Faculty of Physics, “Al.I. Cuza” University, B-dul Carol I, No. 11, Iasi, Romania (e-mail:<br />
rusugxg@uaic.ro)<br />
The interest in the study of CdZnTe (CZT) alloys in thin films has been increased due to their important<br />
applications in technology of thin film devices as solar cells, photo-detectors, gamma-ray detectors,<br />
etc.<br />
Among other preparation techniques of CZT, the physical vapour deposition is often preferred. In<br />
such method, the evaporation of CdTe and ZnTe mixed powder or co-evaporation from dual CdTe<br />
and ZnTe sources are frequently used. An inconvenient of these procedures is the difficulty to control<br />
of Zn content in as evaporated CdZnTe films due to the vapour pressure difference between<br />
CdTe and ZnTe and to the lower sticking coefficient of Zn.<br />
To avoid this inconvenient, in present paper, a modified two source evaporation technique was used<br />
to prepare CdZnTe thin films. Namely, during film deposition, the film substrates, placed onto a rotating<br />
disk, passed successively with constant rate over the CdTe powder and metallic Zn evaporation<br />
sources respectively, separated between them by two glass cylinders. In this way, nanolayered<br />
CdTe/Zn structures with uniform Zn content were deposited. The structural and optical properties of<br />
as deposited CdZnTe films were investigated.<br />
Depending on the preparation conditions, both quasi-amorphous and oriented (111) polycrystalline<br />
films were obtained. Also, depending on Zn content and heat treatment, the value of optical band<br />
gap, E g , for studied films ranged between 1.48 eV and 1.63 eV.<br />
126
JUNE 28 WEDNESDAY AFTERNOON<br />
JS1-WeA-P.2 STUDY OF OPTICAL PROPERTIES OF DIAMOND LIKE CARBON<br />
/POROUS SILICON ANTIREFLECTION COATING LAYERS FOR MULTICRYSTAL-<br />
LINE SILICON SOLAR CELL APPLICATIONS. K. Ait-Hamouda. Labo Instrumentation,<br />
Faculté d’Electronique et informatique, USTHB, BP 32 El-Alia Bab-ezouar Alger, Algérie. M.<br />
Ouchabane. CDTA , Haouche Loukil BP<strong>17</strong>, Baba-Hassen Alger, Algérie. A. Ababou. Labo Instrumentation,<br />
Faculté d’Electronique et informatique, USTHB, BP 32 El-Alia Bab-ezouar Alger, Algérie.<br />
N. Gabouze. UDTS, 2Bd Frantz Fanon BP 399, Alger Algérie<br />
In the past decade, Diamond Like Carbon (DLC) coatings have received great attention essentially<br />
due to their unique properties such as mechanical hardness, adhesion strength and chemical inertness,<br />
and recently in the sensing application, combined with porous silicon. In addition, the same<br />
research group demonstrates an enhancement of the photoluminescence of the porous layer subjected<br />
to a DLC layer deposition.<br />
In this work, we report a study on some optical properties of DLC films. The DLC films have been<br />
deposited by DC discharge plasma enhanced chemical vapor deposition. The deposited layers have<br />
been characterized by spectrophotometry, ellipsometry and FTIR analysis.<br />
The evolution of optical properties for different DLC thickness layers has been correlated with the<br />
FTIR spectra change. In addition, The DLC films have been deposited on multicrystalline solar cell<br />
with a PS film (< 0.3 μm) as an antireflection coating. The results reveal that the solar cell efficiency<br />
strongly depends on the DLC layer thickness. The quantum efficiency of the solar cell coated with a<br />
DLC layer increases by 5% order than the uncoated cell.<br />
125
JUNE 28 WEDNESDAY AFTERNOON<br />
JS1-WeA-P.1 γ N -SHIFTING AS A FUNCTION OF N 2 CONTENT IN AISI 304 NI-<br />
TRIDING. R. Valencia-Alvarado a , A. de la Piedad-Beneitez , J. de la Rosa-Vázquez , R. López-<br />
Callejas , S. R. Barocio , O. G. Godoy-Cabrera , A. Mercado-Cabrera , R. Peña-Eguiluz and A.<br />
E. Muñoz-Castro. Instituto Nacional de Investigaciones Nucleares, Plasma Physics Laboratory, A<br />
P. 18-1027, 11801 México, D.F. Instituto Tecnológico de Toluca, AP 890, Toluca, México. Instituto<br />
Politécnico Nacional, ESIME, 07738, México, D.F. a E-mail: rva@nuclear.inin.mx<br />
We present in this work some experimental results obtained from nitriding AISI 304 stainless steel at<br />
different temperatures by means of RF/DC generated 10 15 -10 16 m -3 density plasmas in the 1-4 eV<br />
temperature range. The samples were biased up to –500 V. Substrate temperatures proof to be an<br />
influential factor in the diffusion of the impinging ions into the material under treatment. In turn,<br />
this temperature during the expanded γ N shift, is a function of the amount of nitrogen introduced to<br />
the sample given by the bias, the depth of the nitrided layer and the plasma characteristics. Thus, we<br />
have chosen the substrate temperature as a global control variable in order to analyze the evolution<br />
of the nitrogen enrichment process through its influence on the X ray diffraction imaging of the γ N<br />
shift in the samples. The optimization of the temperature is explored along with its limits in terms of<br />
the Cr precipitation threshold.<br />
124
JS1 POSTERS<br />
123
JUNE 28 WEDNESDAY AFTERNOON<br />
RIVA-TF-WeA-P.7 GROWTH OF CRYSTAL GERMANIUM-CARBIDE BY IMPLAN-<br />
TATION . Genene Tessema 1,2 1 Faculty of Science, Department of Physics, Addis Ababa University,<br />
P.O.BOX 1<strong>17</strong>6, Addis Ababa, Ethiopia. 2 Helmholtz-Institut für Strahlen und Kernphysik, Nussalle<br />
14-16, 53115 Bonn, Germany<br />
The interactions of carbon with probe nucleus 111 In have been studied in germanium using the perturbed<br />
angular correlation (PAC) method, which has the ability to detect the microscopic environments<br />
of the probe atom by means of the interaction of the nuclear moments of the probe and the surrounding<br />
electromagnetic fields 1,2 . At high dose carbon implantation in germanium two complexes<br />
have been identified by their unique quadrupole interaction frequencies. An interaction frequency of<br />
ν Q = 207(1) MHz (η = 0.16(3)) appeared at annealing temperatures below 650 ο C. Above 650 ο C, it<br />
was replaced by a second interaction frequency of ν Q = 500(1) MHz ( η= 0). The frequencies are attributed<br />
to two different carbon-indium pairs. The orientation of the corresponding electric field gradients<br />
and thermal stability of the defect complexes are studied. The results are found to be in good<br />
agreement with other methods 3 .<br />
1. Th. Wichert, M. Deicher, G. Grübel, R. Keller, N. Schulz and H. Skudlik, Appl. Phys. A 48, 59<br />
(1989)<br />
2. G. Schatz and A. Weidinger, Nuclear Condensed Matter Physics, John Wiley and<br />
Sons, New York (1992)<br />
3. L. Hoffmann, J. C. Bach, and B. Bech Nielsen, Phys. Rev. B ; Vol. 55(<strong>17</strong>), 11 167 (1997)<br />
122
JUNE 28 WEDNESDAY AFTERNOON<br />
RIVA-TF-WeA-P.6 AgInTe 2 CHALCOPYRITE THIN FILMS OBTAINED BY<br />
ELECTRODEPOSITION TECHNIQUES AND ANNEALING. R. Díaz, F. Rueda Dpto. Física<br />
Aplicada Universidad Autónoma de Madrid, 28049 Madrid, Spain. P.Herrasti, E. Vazquez Dpto. Química<br />
Física Aplicada Universidad Autónoma de Madrid, 28049 Madrid, Spain. M. Abd el Lefdil Dpt<br />
de Physique, Université de Rabat, Maroc<br />
In order to obtain single phase thin films of the system Ag-In-Te for thin film solar cell applications,<br />
electrodeposition techniques followed by a baking in Te atmosphere were used. For the formation of the<br />
precursor films three alternative processes were followed, 1t) the co-electrodeposición of Ag and In, 2d)<br />
a layer of Ag with an overlayer of InTe and 3d) a layer of Ag and an overlayer of In. The vacuum<br />
annealing were done with a source of Te metal close to the films that allowed to crystallize into ternary<br />
chalcopyrite phase the as deposited amorphous films. Bath compositions, deposition potentials and<br />
deposition times have been changed to obtain the precursor thin films on substrates of molybdenum<br />
supported by glass. In order to determine the optical properties, SnO 2 coated substrates were also used.<br />
The single phase films are obtained by further annealing in Te atmosphere in the 250-400 o C range with<br />
different cooling profiles. This annealing strongly affects the Te concentration as well as the In/Ag<br />
atomic ratio and the number of phases. Single chalcopyrite phase has been obtained for specific<br />
annealing conditions and is related to Te concentration.<br />
Composition and X-ray studies have been carried out and several phases of AgInTe 2 and In-rich<br />
Telluride chalcopyrites have been found. The film morphology and unit cell parameters for single<br />
phase samples depend strongly on the composition in the annealed samples.<br />
The support of contract No CTQ2005-04469/BQU is acknowledged<br />
121
JUNE 28 WEDNESDAY AFTERNOON<br />
RIVA-TF-WeA-P.5 VAPOUR SOURCE WITH SUBMONOLAYER CONTROL. H. P.<br />
Marques, A. R. Canário, O. M. N. D. Teodoro and A. M. C. Moutinho. CEFITEC, Departamento de<br />
Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2<strong>82</strong>9-<strong>51</strong>6 CAPARICA,<br />
Portugal<br />
To achieve highly accurate controlled depositions a specially designed vapour source was developed.<br />
It provides direct rate and thickness monitoring with submonolayer control.<br />
This compact dosing system basically consists of an evaporation source, a quartz crystal microbalance<br />
and a shutter. The source was intended to evaporate metals with low to medium melting temperature.<br />
It was tested with a high purity Ag wire (99.99%) wrapped around a tungsten filament. Resistive<br />
heating was provided by an adjustable constant current through the filament.<br />
The microbalance and the surface are mounted on the same line with the filament in between. The<br />
careful geometric configuration and distances of the microbalance, filament and surface are such that<br />
only 1/10th of the amount of metal deposited on the quartz crystal is deposited on the sample surface.<br />
Therefore the resolution of the microbalance is extended by one order of magnitude.<br />
The direct thickness measurement by the quartz microbalance with factory parameters was checked<br />
in a calibration experiment. For the calibration an Ag film was deposited on polycrystalline Au surface<br />
and the growth followed with LEIS. The break at the monolayer formation was used to calibrate<br />
the thickness measurements.<br />
This source is being successfully used to study the growth of Ag clusters on TiO 2 . The deposition<br />
rate is a known parameter to control the size of the nanoclusters. During the depositions the mechanical<br />
shutter provides an accurate vapour blanking to the surface. The typical dosing rate may be<br />
as low as 0.035 ML/min, where 1 ML corresponds to 1.4x10 15 atoms.cm -2 .<br />
120
JUNE 28 WEDNESDAY AFTERNOON<br />
RIVA-TF-WeA-P.4 NITROGEN-DOPED TiO 2 THIN FILMS DEPOSITED ONTO<br />
ITO/GLASS SUBSTRATES. Diana Mardare. Al.I.Cuza University, Faculty of Physics, Carol I<br />
Blvd., No.11, Iasi 700506, ROMANIA. Luca Dumitru. Al.I.Cuza University, Faculty of Physics,<br />
Carol I Blvd., No.11, Iasi 700506, ROMANIA<br />
Titanium dioxide films are extensively used in optical thin film device applications owing to their<br />
appropriate optical properties, high thermal and chemical stability in hostile environments. These<br />
films present good durability, a high transmittance in the visible spectral range, and a high refractive<br />
index, so that they are suitable for applications, such as: antireflection coatings, multilayer optical<br />
coatings (used as optical filters), optical waveguides, etc. Also, TiO 2 has focussed a considerable attention<br />
in the past decades as a material with a strong oxidation power, being considered one of the<br />
best photocatalytic material which can be used in order to solve some of the world environmental<br />
problems.<br />
Titanium oxide crystallizes in three different forms: anatase (tetragonal), rutile (tetragonal) and<br />
brookite (orthorhombic) and may also exist in an amorphous state. Rutile is a denser phase than anatase<br />
and brookite, being also the most thermodynamically stable. By changing the deposition parameters,<br />
by performing a heat treatment, or by doping with different impurities, the ratio of the<br />
mentioned phases changes, leading to changes in optical and electrical properties of titanium oxide<br />
thin films [1-3]. The three phases are characterized by different optical properties and determine different<br />
transmittances, optical constants and optical band gaps of the thin films. The catalytic properties<br />
are connected with the large band gap value of the anatase phase (3.2 eV) associated with a low<br />
recombination rate of the charge carriers generated in the surface area by the incident photons.<br />
Undoped and nitrogen-doped titanium oxide films were prepared by reactive magnetron sputtering<br />
onto ITO/glass substrates. Film structure and surface morphology were investigated by X-ray diffraction<br />
and atomic force microscopy. X-ray diffraction (XRD) studies revealed an amorphous structure<br />
of the as-deposited thin films. The surface roughness was derived from AFM imaging. By heat<br />
treatment the amorphous films became polycrystalline. The heat-treated-nitrogen-doped films have a<br />
pure anatase structure, while the undoped ones contain only the rutile phase.<br />
The contact angle of the deionized water with film surface was monitored during both photoactivation<br />
and recovery regimes. The results are discussed in terms of the effects of surface roughness and<br />
of rutile-anatase TiO 2 phase transformation induced by heat treatment and by nitrogen doping, as reflected<br />
in optical transmittance results.<br />
[1] D. Mardare, M. Tasca, M. Delibas and G. I. Rusu, Appl Surf Sci 156 (2000) 200.<br />
[2] A. R. Bally, E. N. Korobeinikova, P. E. Schmid, F. Lévy and F. Bussy, J Phys D: Appl Phys 31<br />
(1998) 1149.<br />
[3] D. Mardare and P. Hones, Mater Sci Eng B 68 (1999) 42.<br />
119
JUNE 28 WEDNESDAY AFTERNOON<br />
RIVA.TF-WEA-P.3 ON THE PHYSICAL PROPERTIES OF PENTACENE THIN FILMS.<br />
Mihaela Girtan a,b Sylvie Dabos – Seignon a , J.M. Nunzi a . a Laboratoire POMA, UMR CNRS 6136,<br />
Université d’Angers, 2 Bd. Lavoisier, 49045 Angers cedex, France, email: mihaela.girtan@univangers.frb<br />
Faculty of Physics, Al.I. Cuza University of Iasi, Romania<br />
Pentacene thin films with thickness ranged between 50 nm and 200 nm were deposited by vacuum<br />
thermal evaporation on glass and ITO substrates at room temperature. The rate of deposition was<br />
about 0.14 nm/s. The influence of substrate nature and films thickness on the film morphology was<br />
investigate by atomic force microscopy (AFM). Electrical and optical investigations were correlated<br />
with the structural and morphological analyses.<br />
118
JUNE 28 WEDNESDAY AFTERNOON<br />
RIVA-TF-WeA-P.2 PHOTOCATALYTIC DEGRADATION OF COMMERCIAL DYES<br />
USED IN THE TEXTILE INDUSTRY BY THE DEPOSITION TiO 2 THIN FILMS ON<br />
GLASS SUBSTRATES. S.M. Marques 1 , C.J. Tavares 1 , V. Teixeira 1 , J.O. Carneiro 1 , A.J. Fernandes<br />
2 .<br />
1 Departamento de Física, Universidade do Minho, 4800-058 Guimarães, Portugal.<br />
2 Departamento de Física, Universidade de Aveiro, 3810-193 Aveiro, Portugal<br />
ctavares@fisica.uminho.pt<br />
The interest in nanoparticle photocatalytic titania (TiO 2 ) thin films has been increasing over the last<br />
few years, due to the self-cleaning nature of these coatings. They have been used on industrial applications,<br />
mainly due their ability to degrade pollutants dissolved in water. Titania acts as a photocatylist<br />
for the dissociation of organic impurities on a particular surface, such as glass. The driving<br />
force behind this photocatalisation is simply ultraviolet (UV) light and atmospheric oxygen. The thin<br />
films of titania were deposited by unbalanced reactive magnetron sputtering, from a high purity Ti<br />
target in an Ar/O 2 atmosphere, with an argon flow rate of 60 sccm (working gas) and a variable oxygen<br />
flow rate in he range of 1.5-9 sccm (reactive gas). Due to the fact that the deposition temperature<br />
is rather low (≈ 200ºC), the titanium dioxide particles that nucleate on the substrate do not have sufficient<br />
energy and mobility to crystallise in a regular lattice, such as Brookite, Anatase or Rutile. In<br />
order to achieve this thermodynamical equilibrium and enhance the composition between the crystallographic<br />
phases, after deposition the samples were thermally annealed in a high vacuum furnace at<br />
different temperatures, 300ºC, 400ºC and 500ºC for 2 hours. In order to comprehend the underlying<br />
structure, X-ray diffraction measurements were then preformed in these heat treated samples and the<br />
composition of the films was study by Rutherford Backscattering spectroscopy (RBS). We also estimated<br />
the thickness of the films made with different flow rates of oxygen and with different times of<br />
deposition, using the Swanepoel’s method for the calculation of the optical properties of the coatings.<br />
The photocatalytic behaviour of the titania coatings was assessed by combined ultra-violet irradiation<br />
and absorption measurements of particular dyes. The observed photo-decomposition of the<br />
aqueous solution (organic pollutants) was measured in the UV/Vis Spectrum by the decrease of the<br />
maximum absorbance with irradiation time. The colour of the dye becomes colourless during this<br />
process, hence indicating that the chemical oxidation-reduction mechanisms abound on the surface<br />
of the titania films. As pollutants, we used dyes that are currently used in the textile industry, as it is<br />
the case of the reactive dye “RED 41”.<br />
1<strong>17</strong>
JUNE 28 WEDNESDAY AFTERNOON<br />
RIVA-TF-WeA-P.1 SEM AND XPS ANALYSIS OF POLYCRYSTALLINE GAN FILMS<br />
GROWN BY CYCLIC PULSED LASER DEPOSITION. P. Sanguino 1 , R. Schwarz 1 . 1 Departamento<br />
de Física, Instituto Superior Técnico, Lisboa, Portugal M. Wilhelm 2 , M. Kunst 2 2 Hahn-<br />
Meitner-Institut, Solare Energetik, Berlin, Germany O. Teodoro 3 Departamento de Física, Universidade<br />
Nova de Lisboa, Monte de Caparica, Portugal<br />
We describe a detailed study of Scanning Electron Microscopy (SEM) combined with Energy Dispersive<br />
Spectroscopy (EDS) analysis to study composition and structure of 500 nm thick polycrystalline<br />
GaN samples. The films have been deposited by Cyclic-Pulsed Laser Deposition (Cyclic-PLD)<br />
with a Nd:YAG nanosecond pulsed laser at 1064 nm. SEM pictures of the GaN layers revealed a<br />
structure composed of grains with typical dimensions of 200 nm. Coalescence of the grains was<br />
more evident for a 1 m thick sample. EDS mapping of the GaN layer was performed for Ga, N, O,<br />
and Al and could be related with the corresponding SEM scan. Both EDS and XPS composition<br />
analysis pointed to a Ga rich (or N deficient) GaN layer.<br />
116
RIVA-TF POSTERS<br />
115
JUNE 28 WEDNESDAY AFTERNOON<br />
RIVA-SS-WeA-P.3 ELECTRON STIMULATED DESORPTION STUDY OF DEFCT<br />
SITES ON THE MgO(100) SURFACE USING QUADRUPOLE MASS SPECTROMETRY<br />
AND TIME OF FLIGHT. I. Colera * , J. L. de Segovia ** , D. Cáceres * , E. Román ** and R. González<br />
* . * Departamento de Física. Universidad Carlos III de Madrid. Leganés. 28911 Madrid. Spain. **<br />
Laboratorio de Física e Ingeniería de Superficies. Instituto de Ciencia de Materiales.<br />
CSIC.Cantoblanco. 28049 Madrid. Spain<br />
While the quadrupole mass spectrometer (QMS) is an excellent tool to identify desorbed ions and<br />
energy thresholds in electron stimulated desorption (ESD) experiments, its analysis of the ion kinetic<br />
energy distribution is questionable. However, time of flight (TOF) is an excellent technique to<br />
analyse the ion energies by using the QMS as the driving tube for the time of flight. The simultaneous<br />
use of the ESDQMS and ESDTOF techniques yields excellent results in the determination of the<br />
ion nature, ion threshold, and ion energy distribution in the study of site defects of on the MgO(100)<br />
surface. Defect sites are identified by exposing the MgO(100) surface to D 2 O and H 2 18 O. Thus, the<br />
D and 18 O can be differentiated from the 16 O and H surface atoms. The energy of the exploring electrons<br />
varied from 200 to 600 eV, and an intensity of 100 nA was used to avoid surface damage. The<br />
sample charge was also studied as a function of the incident electron en energy.<br />
114
JUNE 28 WEDNESDAY AFTERNOON<br />
RIVA-SS-WeA-P.2 SECONDARY ELECTRON EMISSION YIELDS OF EXTER-<br />
NAL DIELECTRIC COATINGS USED IN SPACE . Isabel Montero, Ainhoa Pardo, Pablo<br />
Rios and José Luis de Segovia. Instituto de Ciencia de Materiales de Madrid. CSIC. Cantoblanco.<br />
28049-Madrid. Spain. Luis Galán. Universidad Autónoma de Madrid. Cantoblanco. 28049-Madrid.<br />
Spain. Léon Lévy. Office National d'Etudes et de Recherche Aerospatiales, 2 Avenue Edouard Belin,<br />
31055 Toulouse, Cedex 4, France. Marc Van Eesbeek. European Space Research and Technology<br />
Centre (ESTEC), European Space Agency (ESA), Keplerlaan 1, PO Box 299, NL-2200 AG Noordwijk,<br />
The Netherland<br />
Within ESA Program, AO4136 “Material Characterisation for Plasma Interaction Analysis”, headed<br />
as prime contractor by ONERA, our group from ICMM (CSIC) and UAM has been developing a research<br />
on secondary electron emission and photoemission properties of reliable insulator materials to<br />
study their charging behaviour in space.<br />
The spacecraft surface potential is a function of the net current flow to or from the spacecraft surface.<br />
Electrons impinging on the spacecraft can produce secondary electron emission. Photoemission<br />
from the extreme ultraviolet photon range is the most important since in that region many materials<br />
have rather large photoelectric yields and the solar spectrum also has significant energy there. This<br />
work presents results on secondary electron emission and photoemission yields of space used external<br />
dielectric coatings. The dielectric materials studied was polymers: kapton, betacloth and upilex,<br />
and doped silicon glasses: CMX and CMO.<br />
The total secondary electron emission coefficient, σ, per primary electron, versus primary energy,<br />
Ep, curve was characterized by the following parameters: σm the maximum value and the corresponding<br />
primary energy Em, and the two crossover energies: E1, the lowest Ep for σ =1, and E2 the<br />
highest Ep for σ =1. The beam pulsing measuring technique was used in order to reduce or avoid the<br />
charge incorporation into the samples. SEY was measured for normal incidence and as a function of<br />
primary electron energy. Current pulses of 0.1 -1 μs of low intensity (1nA-50 nA) were used to reduce<br />
the electron dose received by the sample (≤106electrons/pulse). For each primary energy, the<br />
sample was bombarded with only one current pulse. Surface charge decay occurs immediately when<br />
the e-irradiation is stopped, but it depends on the discharging time constants. After each measurement,<br />
the charge of the sample was removed: the trapped charge was liberated with the mercury<br />
lamp (negative surface charging) and the flood-gun (positive surface charging). Analysis of the coatings<br />
was performed, apart from SEY and PES measurements, by XPS (X-ray Photoemission Spectroscopy),<br />
SEM (Scanning Electron Microscopy), EDX (Energy Dispersive X-ray Spectroscopy) and<br />
UVS (Ultraviolet spectroscopy).<br />
113
JUNE 28 WEDNESDAY AFTERNOON<br />
RIVA-SS-WeA-P.1 TiCr ALLOYS OF LOW SECONDARY ELECTRON EMISSION<br />
FOR ANTIMULTIPACTOR APPLICATIONS. G. G. Fuentes and R. J. Rodríguez, AIN-Centro<br />
de Ingeniería Avanzada de Superficies, Cordovilla, 31191, Pamplona, Spain. L. Galán, Departamento<br />
de Física Aplicada. Universidad Autónoma de Madrid. Cantoblanco. 28049-Madrid. Spain. I.<br />
Montero and J. L. Segovia, Instituto de Ciencia de Materiales de Madrid. CSIC. Cantoblonco.<br />
28049-Madrid. Spain<br />
TiCr alloys of low secondary electron emission have been investigated as potential anti-multipactor<br />
coatings. Cathodic-arc evaporation technique in Ar atmosphere was used. The ion energy can be<br />
controlled by the substrate biasing. Chemical state analysis and surface composition were obtained<br />
by X-ray Photoemission Spectroscopy (XPS). Depth profiling was performed by Glow Discharge<br />
Optical Emission Spectroscopy (GDOES). Scanning Electron Microscopy images show the formation<br />
of grains on the surface. The film composition is homogeneous, however, the composition of the<br />
grains varied with their size. Larger grains are richer in titanium, while small ones are rich in chromium<br />
as indicated by energy Dispersive X-ray analysis. Total secondary electron emission yield was<br />
determined by measuring the sample current to ground when bombarded by a primary electron beam<br />
of determined energy. The secondary electron emission coefficient of TiCr alloy exposed to air was<br />
lower than those of chromium or titanium coatings and their nitrides. The experimental secondary<br />
emission yield values together with a Montecarlo model of the secondary emission process were<br />
used to obtain the multipactor threshold.<br />
112
RIVA-SS POSTERS<br />
111
WENESDAY AFTERNOON<br />
POSTER SESSIONS<br />
110
JUNE 28 WEDNESDAY MORNING<br />
WS-18-WeM-INV.12 THE EFFECT OF MECHANICAL AND FRICTIONAL PHE-<br />
NOMENA ON THE QUALITY OF VACUUM IN ADVANCED TECHNOLOGIES. R.A.<br />
Nevshupa. Department of Vacuum Mechanics and Tribology (MT-11), Bauman Moscow State<br />
Technical University, 2-Baumanskaia 5, Moscow 105005, Russia. J.L. de Segovia, E. Roman. Department<br />
of Surface Physics and Engineering, Institute of Material Science of Madrid, C/ Sor Juana<br />
Ines de la Cruz 3, Cantoblanco, Madrid 28049, Spain<br />
By the last quarter of the twentieth century, as the result of several progresses in materials, coatings,<br />
degassing procedure, and pumping technologies, attaining of extremely high vacuum below 10 -8 Pa<br />
had became almost routine task in many technologies ranging from electronic and optoelectronic industries<br />
to large particle accelerators and physical experimental systems. These progresses allowed<br />
to control precisely desorption of gases from stationary surfaces faced to vacuum and to obtain specific<br />
desorption rate from these surfaces below 10 -8 Pa·m 3·m -2·s -1 . In this circumstances secondary<br />
desorption phenomena come to the foreground to provide quality of the total and partial pressures in<br />
technological systems. Tribodesorption, i.e. desorption of gas stimulated by mutual friction, indentation<br />
and other types of mechanical action, is one of the most important among these desorption phenomena<br />
due to high desorption yield and abundance of moving parts in modern ultrahigh vacuum<br />
technological equipment. Specific desorption rate during sliding of stainless steel, other metals and<br />
tribological coatings can be as high as 10 -2 - 10 -3 Pa·m 3·m -2·s -1 . Although contact area, which molecules<br />
are desorbed from, is usually very small, instant pressure increase due to translation of moving<br />
parts inside vacuum system can be of the order of 10 -6 - 10 -7 Pa that is critical for many technological<br />
processes. Moreover, friction is a source of hydrocarbons, carbon oxides, water vapours and other<br />
contaminating substances, which might harm sensitive production.<br />
Tribodesorption is a complex phenomenon based on three main physical sources: desorption of the<br />
topmost adsorbed gas layers, emission of gas molecules from the shallow subsurface zones and tribochemical<br />
reactions. In high and ultrahigh vacuum the late two sources are dominating. The composition<br />
of desorbed gas depends on many factors including kind of material, content of the gas in<br />
the material, presence of adsorbed phases and so on. Time behaviour of tribodesorption has maximum<br />
at the beginning of friction of fresh surface and slowly decreases during friction. However, tribodesorption<br />
rate can be restored after resting time during 12 or more hours or after moderate heating<br />
of the rubbed surface. These facts point the diffusion of gas atoms and molecules in the material<br />
bulk as a precursor of tribodesorption.<br />
In addition, tribodesorption is strongly correlated with any damage of the surface, i.e. plastic deformation,<br />
fracture, cracking, wear and so on. This feature is very promising for developing of reliable<br />
tribological coatings for vacuum applications.<br />
109
JUNE 28 WEDNESDAY MORNING<br />
WS-18-WeM-INV.11 QA EFFORTS IN MANUFACTURING LARGE CRYOPUMP<br />
SYSTEMS FOR NUCLEAR FUSION APPLICATION. Hans S. Jensen and Chr. Day. Institute<br />
for Technical Physics, Forschungszentrum Karlsruhe, 76021 Karlsruhe, Germany.<br />
Forschungszentrum Karlsruhe (FZK) is contributing to the ITER (Latin: The way) project, the next<br />
generation fusion machine. ITER is the experimental step between today’s studies of plasma physics<br />
and tomorrow's electricity-producing fusion power plants. It is an international project involving<br />
many Associations from all over the world. The philosophy of the ITER construction, which is<br />
planned to be ready in ten years from now, is based on in-kind contributions. This means that each<br />
Association is actively taking responsibility for the components it provides to ITER: responsibility in<br />
cost, time, compliance to the Technical Specification, and quality. Within the general Quality Assurance<br />
framework which is set by the ITER Legal Entity, there is quite some flexibility left for the individual<br />
Association as to how fulfil quality aspects for the specific component; this approach is<br />
typical for a big R&D project, such as ITER, involving many prototypical components. Forschungszentrum<br />
Karlsruhe is expected to become the leading Association for provision of the large<br />
tailor-made cryopumping systems for ITER.<br />
This talk exemplifies the FZK experiences of manufacturing and the related quality assurance management<br />
for a recently accomplished R&D project, namely for a cryosorption pumping system used<br />
in a test facility of a neutral beam injector that will be used to heat the plasma of a nuclear fusion reactor<br />
with a beam of deuterium or hydrogen molecules. The huge gas throughput into the vessel of<br />
the test facility results in challenging needs on the cryopumping system, comprising two identical<br />
tailor-made pumps. To establish a mean pressure of several 10 -5 mbar in the test vessel a pumping<br />
speed of about 350 m 3 /s per pump is needed. This was realized with charcoal coated cryopanels<br />
which effectively pump hydrogen. For the cooling of the cryopanels, liquid helium at saturation<br />
pressure is used and therefore a two-phase forced flow in the cryopump system must be controlled.<br />
FZK received the responsibility to design, build, install and test the hardware for this task. The FZK<br />
specified requirements, detailed in 11 individual technical specifications which each included strict<br />
QA requirements. The manufacturing of the components were placed with a large number of industrial<br />
companies within Europe. The central contract for the assembly of the cryopumps was placed<br />
with an industrial company with experience in manufacture of advanced scientific components. This<br />
Main Assembly Contractor (MAC) manufactured the cryopumps using FZK design and drawings,<br />
but MAC also received a number of special components as FZK free issue items, where FZK was responsible<br />
for the testing and quality control before, during and after the manufacture.<br />
This presentation begins with a short outline of the cryopumping system design. It then identifies the<br />
FZK activities during some of the manufacturing processes, in particular the Third Party premanufacturing<br />
approval, construction approval, inspection of approved materials, checking welders´<br />
qualifications, signing quality plans, witnessing the pressure testing, witnessing the vacuum leak testing,<br />
etc. The vacuum integrity of the different circuits is of paramount importance and vacuum leak<br />
testing has been included as holding points in the Quality Plan. All components have been tested to<br />
JUNE 28 WEDNESDAY MORNING<br />
WS-18-TuA-INV.10 SPANISH SYNCHROTRON RADIATION: SOURCE: PRO-<br />
JECT STATUS AND VACUUM SYSTEM. Ll. Miralles and E. Al-Dmour. CELLS, Barcelona.<br />
Spain<br />
The Storage Ring ALBA is a 3 GeV third generation synchrotron light source under construction in<br />
Barcelona (Spain). ALBA is optimized for high photon flux density with a beam emittance of 4.5<br />
nm.rad and a large number of straight sections for Insertion Devices (3´ 8 m, 12´ 4.2 m and 2´ 2.6 m)<br />
in a relatively small circumference of 268.8 m. Top-up operation is foreseen from the start. The injector<br />
complex will consist of a 100 MeV Linac and a full energy Booster with a rather small emittance<br />
9nm.rad. The design of the lattice and of the major components of the accelerator complex<br />
(Linac and Booster, Magnets, RF system, Vacuum system) has been completed and the procurement<br />
procedure has started for the large majority of them. The construction of the building is planned to<br />
start in the first half of 2006 and the commissioning of the storage ring is foreseen for the end of<br />
2008. This report gives an overview of the status of the project.<br />
107
JUNE 28 WEDNESDAY MORNING<br />
WS-18-WeM-INV.9 PHYSICAL AND TECHNOLOGICAL ASPECTS OF MEMS VAC-<br />
UUM PACKAGING. F. Völklein, A. Meier, FH Wiesbaden, University of Applied Sciences. Am<br />
Brückweg 26, D-65428 Rüsselsheim, Germany<br />
The realization of Micro Electro Mechanical Systems (MEMS) or Micro Opto Electro Mechanical<br />
Systems (MOEMS) requires sofisticated fabrication technologies based on thin film deposition,<br />
photolithography and etching techniques. MEMS fabrication can be divided into three<br />
major groups:<br />
i) fabrication with additive and subtractive processes on the wafer level<br />
ii) packaging, involving processes such as bonding, lead attachment and encapsulation in a protective<br />
body or in cavities with reduced gas pressure (vacuum)<br />
iii) testing, including package leak test, electrical integrity and MEMS functionality.<br />
The last two process groups incorporate the most costly steps. MEMS packaging is more difficult<br />
and expensive than packaging of Integrated Circuits (IC) and may be totally different (e.g. for gas<br />
sensors) from IC housing.<br />
MEMS vacuum packaging is required for accelerometers in order to optimize the damping of the devices.<br />
High-Q micro resonators might need a good vacuum. Mechnical vacuum sensors using piezoresistive<br />
or capacitive measuring effects include small cavities (volumes in the order of 1 mm³)<br />
with reduced reference pressure or vacuum.<br />
Cavity sealing can serve as a batch-compatible packaging technique by encapsulating a chip feature<br />
or whole chip at a time. Chip features can be sealed by surface micromachining using Polysilicon or<br />
Silicon Nitride deposition techniques and sacrificial layer technology. Such micromachined surface<br />
packages (microshells) are much smaller than typical bulk MEMS packages. Microshells can be<br />
made by defining thin gaps (100 nm) between the substrate and the perimeter of the structural elements<br />
by etching away a sacrificial layer sandwiched between the two and then sealing the resulting<br />
gaps. In so-called reactive sealing thermal oxidation of the Polysilicon and Si-substrate seals the narrow<br />
openings left after removal of the spacer phosphosilicate (PSG) sacrificial layer. Alternatively,<br />
sealant films, such as oxides and nitrides, can be deposited over small etchant holes. The first commercial<br />
absolut Polysilicon pressure sensor incorporates such a reactively sealed vacuum shell. Epitaxial<br />
cavity sealing and HEXIL cavity sealing are alternative technologies. These and other lithography-defined<br />
packages, such as those involving ultraviolet patternable polymers, might be an integral<br />
part of the overall fabrication processs and lend to inexpensive batch solutions.<br />
In bulk micromachining and Si fusion-bonded (SFB) surface micromachining, cavities are fabricated<br />
by bonding, respectively, a glass plate (anodic bonding) or a Si wafer (fusion bonding) over etched<br />
cavities in a bottom Si wafer. Field-assisted thermal bonding (anodic bonding, also known as electrostatic<br />
bonding) can be established between a sodium-rich glass and Silicon at relatively low process<br />
temperatures. This method is mostly applicable to wafer-scale chip bonding. SFB is performed<br />
between flat Si wafers with slightly oxidized surfaces. When incorporating an intermediate layer between<br />
two substrates, many thermal vacuum bonding techniques are feasible. Silicon microstructures<br />
can be sealed together by eutectic bonding, e.g. Au-Si eutectic bonding at 363°C. The most important<br />
problems of MEMS vacuum packaging are the very small volumes of cavities combined with<br />
the outgassing during the sealing process. Long term stable vacuum in microcavities can be realized<br />
by using thin getter layers and sealing materials with low permeation coefficients.<br />
106
WS-18 SESSION<br />
105
JUNE 28 WEDNESDAY MORNING<br />
JS2-WeM-OR.5 DECORATIVE COATINGS OF TITANIUM OXIDE OBTAINED BY<br />
PVD. J.A. García, R. Martínez. M. Rico and R.J. Rodríguez. Asociación de la Industria Navarra.<br />
C/San Cosme y San Damián s/n, Pamplona 31191 Spain.Email: jagarcia@ain.es<br />
In the last years PVD techniques have strongly emerged in the European market of the decorative<br />
coatings. Faucets and other bath accessories are actually been coated with ceramic films like TiN<br />
(golden yellow) and TiCN (brass) with excellent reproducibility and corrosion resistance, but the use<br />
of these kind of hard coatings just provide a limited list of metallic colours.<br />
In the recent years a wider colour range are been achieved using optical interference phenomena by<br />
depositing nanometric metal Oxide films. It is possible to obtain different colours by controlling the<br />
final thickness of the oxide layers. This article gathers the research to obtain different interference<br />
colours, reports the obtained reflectance curves and tries to find the relations between the oxide<br />
thickness measures by Glow discharge optical emission spectrometry with the colour parameters<br />
measured with a spectrophotometer. Microstructure and thickness had also been measured by using<br />
field emission scanning electron microscopy. As conclusion we can demonstrate that the final colour<br />
is the results of the destructive interference, depending of the relation between the wave length of the<br />
colour and the thickness of the oxide film.<br />
Keywords. Decorative coatings, Interference colours, GDOES, FESEM<br />
104
JUNE 28 WEDNESDAY MORNING<br />
JS2-WeM-OR.4 HARDNESS AND TRIBOLOGY MEASUREMENTS ON ZrN COAT-<br />
INGS DEPOSITED BY REACTIVE SPUTTERING TECHNIQUE. M. A. Auger. Departamento<br />
de Física. Universidad Carlos III. Avda. de la Universidad, 30. 28911 Leganés, Madrid.<br />
Spain. J. J. Araiza. Unidad Académica de Física. Universidad Autónoma de Zacatecas. Avda. Preparatoria<br />
Nº 301. Fracc. Progreso. Zacatecas, Zac. 98000 Méjico. C. Falcony. Departamento de Física.<br />
CINVESTAV-IPN. Aptdo. 14-740. Méjico D.F. 07360 Méjico. O. Sánchez and J.M. Albella. Departamento<br />
de Física e Ingeniería de Superficies. Instituto de Ciencia de Materiales de Madrid-CSIC. C/<br />
Sor Juana Inés de la Cruz, 3. 28049 Cantoblanco, Madrid. Spain.<br />
Thin films based on transition metal nitrides have been widely used in many applications because of<br />
their interesting properties (mechanical, tribological, chemical stability, etc.) together with their<br />
shiny and golden appearance, which make them highly attractive for applications as protective and<br />
decorative coatings in different industrial and commercial sectors.<br />
In this work, a series of ZrN coatings have been grown in a rf sputtering deposition chamber, where<br />
different ratios of Ar/N 2 gases (5/1, 5/5, 1/5 sccm) were introduced during the process as a reactive<br />
atmosphere. Once deposited, the coatings were thermally treated in a 500 o C oxygen atmosphere trying<br />
to promote the oxynitride formation (ZrNO), which has been proposed as a suitable material for<br />
being used as optical and decorative coatings. Due to the incorporation of oxygen to the matrix of<br />
covalent metal-nitrogen bonds, the electronic properties are modified giving place to interesting<br />
changes in the colour range of the coatings, thus allowing the control of the surface appearance in<br />
decorative applications.<br />
The chemical composition, mechanical and tribological properties of the as-deposited and thermally<br />
treated samples have been measured by different techniques: EDX, nanoindentation and pin-on-disk<br />
techniques respectively. ZrN samples grown at 5 sccm Ar + 1 sccm N 2 showed a composition close<br />
to the stoichiometry, and offered the best mechanical and tribology behaviour. These samples, after<br />
being subjected to the oxygen thermal treatment, improve even more their hardness, making them<br />
more suitable for protective and decorative purposes.<br />
103
JUNE 28 WEDNESDAY MORNING<br />
JS2-WeM-OR.3 TRIBOLOGICAL CHARACTERIZATION OF TUNGSTEN NITRIDE<br />
COATING AT ELEVATED TEMPERATURE. T. Polcar, N.M.G. Parreira and A. Cavaleiro a *.<br />
ICEMS – Grupo de Materiais e Engenharia de Superfícies, Faculdade de Ciências e Tecnologia da<br />
Universidade de Coimbra – Pólo II, 3030-201 Coimbra, Portugal. * To whom all correspondence<br />
should be addressed (albano.cavaleiro@dem.uc.pt)<br />
Transition metal nitrides are known for the unique combination of excellent mechanical properties<br />
(hardness and Young’s modulus), high melting point, good chemical stability and high electrical<br />
conductivity. However, tungsten nitrides still stand aside of the main attention, particularly compared<br />
to titanium or chromium nitrides. The first studies of tungsten nitrides thin films were performed, basically,<br />
for electronic applications such as, semiconductors or diffusion barriers. In the 90´s, W-N<br />
coatings were started to be studied for mechanical applications and further studies were performed<br />
on the addition of different elements (e.g. W-Ti-N and W-Si-N) in order to improve their mechanical<br />
properties. There are only few studies dealing with tribological properties of tungsten nitrides and<br />
showing their good wear resistance. In our previous study, tungsten nitride coatings with different nitrogen<br />
content showed excellent wear resistance in case of sliding against ceramic Al 2 O 3 and Si 3 N 4<br />
balls. However, many engineering applications require good tribological properties, particularly wear<br />
resistance, at elevated temperature. Thus, the present study is focused on the tribological behaviour<br />
(friction coefficient and wear rate) of tungsten nitride coating at temperature in the range 20 - 600°C.<br />
The structure, hardness, friction and wear of tungsten nitride coating prepared by dc reactive magnetron<br />
sputtering were investigated. The tribological tests were performed on a pin-on-disc tribometer<br />
in terrestrial atmosphere with Al 2 O 3 balls as sliding partner. The wear tracks and the ball wear scars<br />
were investigated by scanning electron microscopy in order to characterize the dominant wear<br />
mechanisms. The coating wear rate was negligible up to 200°C exhibiting a decreasing tendency;<br />
however, the wear dramatically increased at higher temperatures. The coating peeled off after the test<br />
at 600°C.<br />
102
JUNE 28 WEDNESDAY MORNING<br />
JS2-WeM-INV.2 TRIBOLOGICAL CHARACTERIZATION OF METAL CAR-<br />
BIDE/AMORPHOUS CARBON NANOCOMPOSITES: FROM MACRO TO THE MICRO-<br />
SCALE. J.C. Sánchez-López*, D. Martínez-Martínez, C. López-Cartes, A. Fernández. Instituto de<br />
Ciencia de Materiales de Sevilla, CSIC-Universidad de Sevilla, Avda. Américo Vespucio 49, 41092-<br />
Sevilla, Spain. *E-mail: jcslopez@icmse.csic.es<br />
The design of multilayered and nanocomposite coatings structures have allowed to achieve superior<br />
hardness, toughness and excellent wear resistance useful for many industrial applications. The optimization<br />
of the tribological performance of such materials represents a challenge as depends not only<br />
on factors intrinsic to the coatings (chemical composition, microstructure, phase composition, texture…)<br />
but, besides, others related to the application conditions (adhesion to the substrate, nature of<br />
the counterfaces, environment, load, etc.). In this work, we review the results obtained for nanocomposite<br />
coatings made of nanocrystalline metal carbides and amorphous carbon (a-C) prepared by<br />
PVD techniques. Their characterization appears complicated mainly due to the lack of long-range<br />
order and the heterogeneity in chemical compositions at the nanometric scale. The nanocrystalline/amorphous<br />
ratio appears to be a key-parameter to control the tribological properties and its<br />
quantification results always not easy. Focusing mainly in the TiC/a-C system prepared by magnetron<br />
sputtering as example, it is showed how the investigation of chemical and structural features at<br />
the micro-scale help to determine the aspects influencing the tribological performance at the macroscale.<br />
By varying the power applied to each target (titanium or graphite), it was possible to prepare a<br />
wide family of film structures covering from a quasi-polycrystalline TiC to a nanocomposite formed<br />
by nanocrystals of TiC. The microstructure of one coating, shown in Fig. 1, reveals a nanometric<br />
grain boundary network around TiC crystals of 5 to 10 nm. A complete characterization has been accomplished<br />
by X-ray diffraction (XRD), atomic force microscopy (AFM), transmission electron microscopy<br />
(TEM), electron diffraction and electron energy-loss spectroscopy (EELS) and X-ray photoelectron<br />
spectroscopy (XPS), pin-on-disk and nanoindentation measurements. EELS and XPS<br />
techniques are demonstrated to be very appropriate tools for the estimation of the amorphous phase<br />
inside the nanocomposite because they are sensitive to the bonding environment. In the Fig. 2 it is<br />
depicted the modification of the shape and position of the C K-edge for different coatings when the<br />
contents of TiC and a-C are varied. The increment of the TiC contribution is accompanied by a gradual<br />
rise of the friction coefficient due to the lack of sufficient amorphous lubricant phase. Combining<br />
the complementary information given by the different techniques it was possible to obtain a mapping<br />
of the tribological and mechanical properties as a function of the synthesis conditions that helps in<br />
the selection of the best coating for specific applications.<br />
Fig. 2 C K-edge<br />
EELS spectra and<br />
associated friction<br />
values for different<br />
TiC/a-C coatings<br />
Fig. 1: HRTEM image for a TiC/a-C film<br />
101
JUNE 28 WEDNESDAY MORNING<br />
JS2-WeM-OR.2 WEAR RESISTANCE OF TITANIUM-ALUMI-NIUM-CHRO-<br />
MIUM-NITRIDE NANOCOMPOSITE THIN FILMS. A. Alberdi, M. Marín, B. Díaz.<br />
Fundación Tekniker. Avda. Otaola, 20. 20600 Eibar (Spain). O. Sánchez. Institute of Materials<br />
Science (ICMM). Cantoblanco, 28049 Madrid (Spain)<br />
Titanium nitride, titanium-aluminium nitride and chromium nitride are now used widely in<br />
manufacturing industry to protect cutting and forming tools against wear. TiN was the first<br />
PVD ceramic coating to be used successfully to machine steel in industry and it is still the most<br />
recognized. TiN is a wear resistant coating suitable for a wide range of applications. It is used<br />
for machining carbon stainless steels, cast irons and aluminium alloys, protecting dies, moulds<br />
and a range of metal stamping and forming tools. However, TiN has now been superseded in<br />
many applications by TiAlN, which offers superior performance for a range of metal machining<br />
and fabrication applications. It has been pointed out that the reason for this better performance<br />
is the formation of aluminium oxide on the surface, which increases its operational temperature<br />
range. Although CrN is softer than TiN, CrN is a tough ceramic coating with good<br />
oxidation resistance. Presently, CrN is the PVD hard coating recommended for most metal<br />
forming applications.<br />
Advanced PVD coatings based on TiAlN are being developed recently, which possess enhanced<br />
high temperature oxidation and wear resistance. Typical strategy to enlarge the temperature<br />
range of TiAlN is the addition of metals able to generate high resistant oxides, like<br />
chromium, molybdenum, yttrium or vanadium.<br />
In this way, authors have developed novel TiAlCrN multilayered nanocomposite thin films,<br />
which alternate CrN and TiAlN individual 10-12 nm thickness layers up to a total thickness of<br />
1-3 μm. These coatings were grown on WC-Co inserts and high speed steel samples by simultaneous<br />
arc evaporation of pure Cr and Ti-Al alloy targets. Wear resistance of these coatings<br />
was studied through high temperature pin-on-disk experiments. Results demonstrated that this<br />
kind of coating structures improved several times the wear resistance at high temperature of<br />
commercially available TiAlN coatings.<br />
Key words: TiAlCrN ceramic coatings, physical vapour deposition, high temperature wear resistance.<br />
100
JUNE 28 WEDNESDAY MORNING<br />
JS2-WeM-OR.1 TRIBOLOGICAL PROPERTIES OF SILICON NITRIDE CERAMICS<br />
COATED WITH DLC AND DLC-Si AGAINST 316L STAINLESS STEEL J. R. Gomes. Departamento<br />
de Engenharia Mecânica, CIICS, Universidade do Minho, 4800-058 Guimarães, Portugal.<br />
J. M. Carrapichano. Departamento de Engenharia Mecânica, Instituto Superior de Engenharia de<br />
Coimbra, 3040-228 Coimbra, Portugal. S. S. Camargo Jr., R. A. Simão, C. A. Achete. Departamento<br />
de Engenharia Metalúrgica e de Materiais, Universidade Federal do Rio de Janeiro, Cx. Postal<br />
68505, 21945-970 Rio de Janeiro, RJ, Brazil. R. F. Silva. Departamento de Engenharia Cerâmica e<br />
do Vidro, CICECO, Universidade de Aveiro, 3810-193 Aveiro, Portugal.<br />
Diamond-like carbon (DLC) is an adequate coating on a large variety of materials for tribological<br />
purposes. Its intrinsic hardness, smoothness and solid lubricious capability are key properties that afford<br />
an outstanding combination of low friction coefficient and high wear resistance. However, the<br />
performance of a tribosystem is also determined by the type of counterface material, the environmental<br />
conditions and the presence or not of interfacial media. For example, in the automotive parts<br />
industry, the valve guides or the transmission gears are today coated with DLC. Another practical<br />
example of contacts that may involve steel as the mating material of DLC are forming tools to manufacture<br />
steel products. Plasma enhanced chemical vapour deposition (PECVD) of DLC-Si or pure<br />
DLC coatings were performed, respectively, by conventional rf glow discharge from gaseous mixtures<br />
of methane and silane or taking only pure methane. In this work, an engineering ceramic, silicon<br />
nitride (Si 3 N 4 ), is used as DLC substrate aiming the minimization of adhesion problems, usually<br />
found when some metallic substrates are employed. The ceramic substrates were placed onto the<br />
cathode of the deposition system where the rf power was applied achieving self-bias voltages varying<br />
from -200 to -800 V.<br />
The tribological properties were assessed by pin (316L stainless steel)-on-disc (Si 3 N 4 ) experiments,<br />
without lubricant, at room temperature, under ambient air and 50-60% relative humidity. The normal<br />
applied load assumed the values of 10 N and 20 N. The sliding speeds varied from 0.2 m/s to 1.0<br />
m/s. The characterisation of the disc and pin worn surfaces was carried out by scanning electron microscopy<br />
provided with energy dispersive X-ray spectrometry (SEM/EDS) and atomic force microscopy<br />
(AFM). A first set of experiments was carried out in order to compare the tribological behaviour<br />
of DLC-Si and pure DLC coatings on Si 3 N 4 . An early partial delamination of the DLC-Si coatings<br />
was observed, although leading to a steady-state friction regime with friction coefficients<br />
around 0.14, a low value in unlubricated conditions. This favourable frictional response is due to the<br />
wear-induced surface graphitisation and to the role of self-lubricating layers of adhered debris in<br />
both the sliding surfaces. The stainless steel contact surface was extensively covered by a Si, C and<br />
O rich tribolayer, promoting a third-body protection to the steel pin. An improved tribological response<br />
was obtained with pure DLC coated Si 3 N 4 discs sliding against the stainless steel pins. This<br />
system almost instantaneously attains the steady-state friction regime, keeping the DLC film integrity,<br />
contrarily to the DLC-Si damaging, which leads to noisy friction curves coming from cyclic<br />
frictional events. The preservation of the coating demonstrates an adequate adhesion for tribological<br />
purposes up to 20 N of applied load. The wear coefficient of the pure DLC coated Si 3 N 4 disc was, at<br />
least, one order of magnitude lower than that of the DLC-Si coated one, always below 10 -6 mm 3 N -<br />
1 m -1 . The set of tribological experiments of pure DLC coatings obtained under distinct self-bias application<br />
during the PECVD process revealed that the wear coefficient values obtained for the –200V<br />
biased coating are slightly better than those presented by the –800V biased one. However, with respect<br />
to the friction coefficient values, a trend to lower values occurs for the –800V biased films.<br />
Additionally, the typical friction pattern for low biased grown coating is much more unstable than<br />
the very smooth one of the –800V biased film.<br />
99
JUNE 28 WEDNESDAY MORNING<br />
JS2-WeM-INV.1 SURFACE ANALYSIS OF NITRIDES AND OXYNITRIDE COM-<br />
POUNDS WITH ION BEAMS. E. Alves, N. P. Barradas, Instituto Tecnológico Nuclear, EN. 10,<br />
2686-953 Sacavém .F. Vaz, L. Rebouta, C. Tavares, Universidade do Minho, Departamento de<br />
Física, 4800-058 Guimarães, Portugal. U. Kreissig, Forschungszentrum Rossendorf e.V., Postfach<br />
<strong>51</strong>0119, 01314 Dresden, Germany.<br />
Titanium nitride and oxynitride compounds exhibit interesting properties for applications in fields<br />
ranging from protective/decorative coatings to solar panels. The properties of these compounds are<br />
related to the oxide/nitride ratio and can be tailored by tuning this ratio. Then, accurate composition<br />
measurements are fundamental to understand the behaviour of these structures. Ion beam based techniques<br />
(IBA) are unique for this purpose. The composition throughout the entire thickness of the<br />
films was determined by Rutherford Backscatering Spectrometry (RBS). To get information on the<br />
profile of light elements (O, N) and detect the presence of hydrogen on the films, heavy ion elastic<br />
recoil detection analysis (HI-ERDA) was performed.<br />
The results indicate a nearly constant stoichiometry through the entire analysed depth. The oxygen<br />
fraction in the films increases with gas flow, reaching a value of x~0.33 for a reactive gas flow mixture<br />
of 6.25 sccm The colouration varied from the shiny golden for low oxygen contents (characteristic<br />
of TiN films) to dark blue for higher oxygen contents. During growth mixed zirconium nitride<br />
and oxide phases form. Furthermore, the deposition rate correlates with the oxygen content variations,<br />
showing a continuous decrease with reactive gas flow.<br />
98
JS2 SESSION<br />
97
JUNE 28 WEDNESDAY MORNING<br />
RIVA-SS-WEM-OR.8 THE TRIBOLOGICAL BEHAVIOUR OF W-S-C FILMS IN PIN-<br />
ON-DISK TESTING AT ELEVATED TEMPERATURE. M. Evaristo, T. Polcar, A. Cavaleiro,<br />
ICEMS -Faculdade de Ciências e Tecnologia da Universidade de Coimbra, Dep. Eng. Mecânica, Rua<br />
Luís Reis Santos, 3030-788 Coimbra, Portugal<br />
Transition metal dichalcogenides (TMD) are well known for their self lubricant properties, due to<br />
unique crystal structure. However, the structure of TMD presents some drawbacks, particularly, they<br />
have low hardness making them inappropriate to applications requiring high load bearing capacity.<br />
Moreover, TMD films exhibit morphologies with high porosity promoting oxidation, particularly in<br />
humid atmosphere or elevated temperature.<br />
Several approaches have been used to increase the mechanical properties of TMD thin films. One of<br />
the most successful is either doping TMD with a metal, which increases hardness, or the deposition<br />
of an interlayer improving adhesion. MoS 2 is one of the most studied TMD, showing good results<br />
when deposited with an interlayer and doped with Ti, Cr, and other metals.<br />
There is a reference in literature showing that WS 2 has higher oxidation resistance than MoS 2 (about<br />
100ºC), therefore, it is a good candidate for films with good tribological behaviour at high temperatures.<br />
Previous works showed that the hardness and adhesion of W-S films doped with C or N deposited<br />
with a Ti interlayer significantly increased compared to pure WS 2 . The analysis of friction and<br />
wear behaviour at elevated temperatures was the main aim of this study.<br />
W-S-C films were deposited by magnetron sputtering in an Ar atmosphere with a Ti interlayer. A<br />
carbon target with several pellets of WS 2 incrusted in the zone of the preferential erosion was used.<br />
The number of pellets was changed to modify the carbon content in the films, which varied from 26<br />
up to 70at.%. Doping W-S films with carbon lead to a substantial increase of the hardness in the<br />
range 4 to 10GPa; the maximum of hardness was obtained for coatings with the carbon content of<br />
40at.%.<br />
The XRD diffraction patterns showed that there was a loss of crystallinity with the increase of the<br />
carbon content in the film. SEM images of the cross section of the films showed decrease of the dimensions<br />
of the columnar structure and decrease of the porosity as the carbon content in the films increased.<br />
The coatings were tested by pin-on-disk from room temperature (RT) up to 400ºC. At RT, the friction<br />
coefficient was in range 0.3-0.1, and the wear rate decreased with the carbon content. At temperatures<br />
higher than 100ºC, the friction is below 0.1 for all compositions, which can be explained<br />
by the atmosphere drying.<br />
The tribological behaviour of the coatings with increasing temperatures depends on the films carbon<br />
content. For low carbon content up to 40at.%, the wear rate was almost independent of the temperature<br />
up to 300º, while it increased dramatically in case of coatings with high carbon content. The<br />
highest carbon content (∼70at.%) coatings were peeled off from the substrate at temperatures exceeding<br />
100 ºC. In general, the limiting temperature for W-S-C coatings is 400ºC.<br />
96
JUNE 28 WEDNESDAY MORNING<br />
RIVA-SS-WEM-OR.7 AB INITIO CALCULATIONS FOR THE EXCITED STATE AND<br />
THE CATION OF DIPHENYL ETHER AND COMPARISON WITH REMPI EXPERI-<br />
MENTS. M. Guerra and A. C. S. Paiva. CEFITEC Department of Physics, Faculdade de Ciências<br />
e Tecnologia, Universidade Nova de Lisboa, 2<strong>82</strong>9-<strong>51</strong>6, Caparica, Portugal.<br />
The structure and minimum energy conformations of diphenyl ether (Ph 2 O) both for the ground state<br />
and the first excited state are calculated using HF/6-311++G**, MP2/6-311++G**, BLYP/6-<br />
311++G** and B3LYP/6-311++G** ab initio and density functional computations. Potential energy<br />
surfaces are also obtained for the rotation of the phenyl rings relatively to the C-O-C plane both for<br />
the neutral molecule and the positive ion. The global minimum of the Ph 2 O potential energy surface<br />
was found to be a “twisted” conformation and it doesn’t change with the excitation to the first excited<br />
state nor with a single ionization, altough the C-O-C-C dihedral angle varies slightly and the<br />
molecule floppyness decreases. An initial study of the molecule fragmentation was performed at<br />
B3LYP/6-311++G** theory level.<br />
The spectra of Ph 2 O cooled in a supersonic jet expansion, obtained with one-color resonance enhanced<br />
two-photon ionization suggests the existence of different conformations [1] . The first excited<br />
state low-frequency vibrations for three of the conformers were investigated using a Configuration<br />
Interaction aproach (CI-Singles) and Complete Active Space Multiconfiguration Self Consistent<br />
Field (CASSCF) method. The comparison between the calculated and observed spectra for all the<br />
conformers thus allows us to assign the major bands.<br />
Keywords: Conformational analysis; Diphenyl ether; Photoionization; Ab initio calculation<br />
[1] A. C. S. Paiva et al., International Journal of Mass Spectrometry 221 (2002) 107-115<br />
95
JUNE 28 WEDNESDAY MORNING<br />
RIVA-SS-WeM-OR.6 SURFACE ANALYSIS OF NBR ELASTOMERS MODIFIED<br />
WITH DIFFERENT PLASMA TREATMENTS. L. Martínez, L. Álvarez, Y. Huttel, J. Méndez,<br />
E. Román. Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC) Cantoblanco, 28049-Madrid,<br />
Spain. A. Vanhulsel, B. Verheyde, R. Jacobs, Flemish Institute for Technological Research (VITO).<br />
Boeretang 200, 2400-MOL, Belgium.<br />
In this work, three rubber–like materials with applications applied in the automotive industry were<br />
studied: two Nitrile Butyl Rubber (NBR 7201 and NBR 9003) and one Hydrogenated Nitrile Butyl<br />
Rubber (HNBR 8001). Different atmospheric pressure plasma treatments were used to modify the<br />
surface properties of these materials in order to improve their tribological (properties). Surface<br />
analysis of the samples by means of X-ray Photoelectron Spectroscopy (XPS) was performed in order<br />
to get information about the surface chemistry and the elemental composition of the contact surfaces.<br />
In addition, wetting experiments were also performed by measuring the contact angle with in<br />
the frame of the sessile drop method. The obtained results allow an evaluation of the surface free energy<br />
of the solids and of the impact of different plasma treatments. The XPS results showed a modification<br />
of the surface composition of both NBR rubbers, while the same treatments produced slight<br />
modifications on the surface chemistry of the HNBR. The main modification was based on an increase<br />
in the oxygen content. The combination of N 2 and CH 3 COOH produced the strongest modifications<br />
of the surface composition of the tested elastomers. All these surface modifications also produced<br />
a change on the surface energy of the rubber-like materials. The results obtained in the contact<br />
angle measurements revealed that the plasma treatments produced a modification of the wettability<br />
of the rubber-like NBRs and, therefore, a modification of their surface free energy.<br />
94
JUNE 28 WEDNESDAY MORNING<br />
RIVA-SS-WeM-OR.5 DEVELOPMENT OF AN APPLICATION FOR MONI-<br />
TORIZATION AND ANALYSIS OF THE ELECTRIC SIGNAL OF AN ULTRAVIOLET<br />
PHOTOELECTRON SPECTROMETER. P. M. S. Cristo, A. A. Dias, P. Vieira, M. L. Costa.<br />
1 Centre for Physics and Technological Research, CEFITEC, 2 Departamento Física, Faculdade de<br />
Ciências e Tecnologia, Universidade Nova de Lisboa, Monte de Caparica, 2<strong>82</strong>9-<strong>51</strong>6, Caparica, Portugal.<br />
e-mail: aad@fct.unl.pt<br />
The development of an application for monitorization and analysis of the electric signal of an ultraviolet<br />
photoelectron spectrometer [i], witch allows for more precision in both the spectrometer<br />
analysis parameters and in the collected data, is presented.<br />
The principal features are the control of the voltage applied to the analyser hemispheres and the acquisition<br />
of counts from the spectrometer.<br />
A Labview programming environment was chosen, jointly with a Data Acquisition board for the<br />
counting, input and output data.<br />
The construction of a Digital-Analogic converter is also included in the project in order to convert<br />
the digital signal available in the acquisition board and controlled by the Labview to analogical data<br />
for input in the spectrometer.<br />
References<br />
[i] F. Innocenti, L. Zuin, M.L. Costa, A.A. Dias, A. Morris, A.C.S. Paiva, S. Stranges, J.B. West,<br />
J.M. Dyke, J. Elec. Spec. Rel. Phen. 2005, 142, 241-252.<br />
93
JUNE 28 WEDNESDAY MORNING<br />
RIVA-SS-WeM-OR.4 DESIGN OF AN ELECTROSTATIC LENS SYSTEM FOR AN<br />
ULTRAVIOLET PHOTOELECTRON SPECTROMETER. R. M. Pinto 1,2 , A. A. Dias 1,2 and<br />
M. L. Costa 1,2 . 1 Centre for Physics and Technological Research, CEFITEC, 2 Departamento Física,<br />
Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Monte de Caparica, 2<strong>82</strong>9-<strong>51</strong>6,<br />
Caparica, Portugal e-mail: aad@fct.unl.pt<br />
The control of an electron beam plays an important role in most of the electron spectrometer systems,<br />
nowadays. Although the use of electrostatic lenses, for purposes of focusing the particles, is<br />
not always necessary, the overall quality of the system in which they are inserted can be improved.<br />
This work aims to design an electrostatic lens system [i] that improves the resolution at the entrance<br />
of a hemispherical deflection analyzer, of a working ultraviolet photoelectron spectrometer [ii,iii],<br />
while maintaining a constant transmission.<br />
The spectrometer does not have any kind of controlled focusing device other than a spatial collimator.<br />
An optimal solution has to be found, concerning the dimensions of the existing apparatus. Simulations<br />
using ion optics programs and the study of several lenses configurations are the suitable<br />
means to reach such a goal. The existence of aberrations is taken into account.<br />
References<br />
[i] O. Sise, M. Ulu, M. Dogan. Nucl. Instr. and Meth. in Phys. Res. A 2005, 554, 114-131.<br />
[ii] J.M. Dyke, G. Levita, A. Morris, J.S. Ogden, A.A. Dias, M. Algarra, J.P. Santos, M.L. Costa,<br />
P. Rodrigues, M. Andrade, M.T. Barros. Chem. Eur. J. 2005, 11, 1665-1676.<br />
[iii] L. Beeching, A.A. Dias, J.M. Dyke, A. Morris, S. Stranges, J. West, N. Zema, L. Zuin, Molecular<br />
Physics 2003, 101, 575-5<strong>82</strong>.<br />
92
JUNE 28 WEDNESDAY MORNING<br />
RIVA-SS-WeM-OR.3 WORK FUNCTION CHANGES INDUCED BY TEMPERATURE<br />
IN Ag/TiO 2 SURFACES. H. P. Marques, A. R. Canário, A. M. C. Moutinho and O. M. N. D.<br />
Teodoro CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade<br />
Nova de Lisboa, 2<strong>82</strong>9-<strong>51</strong>6 CAPARICA, Portugal<br />
When one studies the catalytic behaviour of a surface, the energy required to remove electrons from<br />
the surface is a meaningful parameter since electron transfer is involved in many surface reactions.<br />
Therefore, the surface work function is important to understand the mechanisms of heterogeneous<br />
catalysis.<br />
Growth dynamics of silver clusters supported on TiO 2 (110) mono-crystals have been studied by<br />
several authors [1-5]. Silver atoms deposited in the crystal at room temperature exhibit a 3D Volmer-<br />
Weber growth mode. When the substrate is cooled to LN 2 temperature, the Ag atoms have very low<br />
surface mobility and a quasi-2D growth is observed [2].<br />
The work function measurements performed during cluster growth show different behaviour depending<br />
on the substrate temperature, which translates on the cluster size [6]. During growth, at lower<br />
temperature the WF changes more rapidly and tends to a lower value than at room temperature.<br />
In this work we studied the work function as a function of the substrate temperature. One equivalent<br />
monolayer of silver was deposited on a TiO 2 (110) surface at LN 2 temperature and a base value for<br />
the work function was determined. The substrate was then annealed for 5 minutes. The sample was<br />
allowed to cool down again to LN 2 temperature and the work function was measured. The procedure<br />
was repeated for increasing annealing temperatures up to 200ºC.<br />
For all work function measurements the onset method was used. The secondary electron threshold is<br />
shifted in energy according to the work function change.<br />
Keywords: Work function, titanium oxide, silver clusters.<br />
[1] U. Diebold, Surface Science Reports, 48 (2003) 53.<br />
[2] C.T. Campbell, Surf. Sc. Reports, 27(1997) 1 111<br />
[3] C. Su, J.C. Yeh, J.L. Lin and J.-C. Lin, App. Surf. Sci. 169 (2001) 366.<br />
[4] K. Luo, T.P. St Clair, X. Lai, and D.W. Goodman, J. of Phys. Chem. B 104 (2000) 3050.<br />
[5] A.R. Canário, E.A. Sanchez, Yu. Bandurin and V.A. Esaulov, Surf. Sci. 547 (2003) L887<br />
[6] H.P. Marques, A.R. Canário, O.M.N.D. Teodoro and A.M.C. Moutinho Riva V<br />
proceedings, submitted to Vacuum<br />
91
JUNE 28 WEDNESDAY MORNING<br />
RIVA-SS-WeM-OR.2 PLANAR MAGNETRON DISCHARGE. AN EXPERIMENTAL<br />
PROFILE ANALYSIS OF THE TARGET EROSION BASED ON A TWO-DIMENSIONAL<br />
FLUID MODEL IN THE STEADY STATE. M. L. Escrivão, P. J. S. Pereira*, M. R.<br />
Teixeira and M. J. P. Maneira. CeFITec, Departa-mento de Física, Faculdade de Ciências e Tecnologia<br />
da Universidade Nova de Lisboa, Quin-ta da Torre, 2<strong>82</strong>9-<strong>51</strong>6, Caparica, Portugal. * Also in<br />
Área Científica da Matemática, Instituto Superior de Engenharia de Lisboa, Rua Conselheiro<br />
Emídio Navarro, 1949-014 Lisboa, Portugal<br />
.<br />
In the present work the erosion depth is measured along a diameter of a circular magnetron target.<br />
The horizontal and vertical components of the magnetic induction are measured at points of the<br />
plasma that are vertically above this diameter and at different distances from the target.<br />
The experimental profile of the target erosion is analysed on the basis of the plasma density distribution<br />
near the target which is obtained using a two-dimensional fluid model in the steady state.<br />
90
JUNE 28 WEDNESDAY MORNING<br />
RIVA-SS-WeM-OR.1 USE OF A RADIO-FREQUENCY POWER SUPPLY COUPLED<br />
TO A HIGH TEMPERATURE FURNACE IN ULTRAVIOLET PHOTOELECTRON SPEC-<br />
TROSCOPY. E. M. C. C. Reis 1,2 , A. A. Dias 1,2 , O. M. N. D. Teodoro 1,2 and M. L. Costa 1,2 . 1 Centre<br />
for Physics and Technological Research, CEFITEC. 2 Departamento Física Faculdade de Ciências e<br />
Tecnologia, Universidade Nova de Lisboa, Monte de Caparica, 2<strong>82</strong>9-<strong>51</strong>6, Caparica, Portugal. e-<br />
mail: aad@fct.unl.pt<br />
Temperatures up to 2500 ºC have to be attained for analysing solid samples by Ultraviolet Photoelectron<br />
Spectroscopy (UVPES), using a high temperature furnace[i]. A radio-frequency (RF) power<br />
supply seems ideal for this purpose [ii].<br />
The RF source, operating near the photoelectron spectrometer, creates an electromagnetic field that<br />
causes interference in photoelectron trajectories. In order to eliminate this effect the RF power supply<br />
should be used in a pulsed mode in conjunction with a linear gate in detector circuits.<br />
The frequency chosen to obtain these pulses is of 50 Hz, since that is the frequency used by the<br />
mains. The 50 Hz waves are rectified, being allowed to pass only the positive voltages, eliminating<br />
the negative ones.<br />
Considering that the maximum power available from the generator is reduced to less than half of its<br />
original value, as a result of the pulses, a considerable amount of power is necessary to raise the<br />
temperature.<br />
Modifications performed in both a RF power supply and detector circuits, together with its coupling<br />
to an existing high temperature furnace will be presented.<br />
References<br />
[i] J.M. Dyke, G. Levita, A. Morris, J. S. Ogden, A.A. Dias, M. Algarra, J.P. Santos, M.L. Costa,<br />
M.T. Barros, J. Phys. Chem. A 2004, 108, 5299-5307.<br />
[ii] D. Bulgin, J. Dyke, F. Goodfellow, N. Jonathan, E. Lee, A. Morris, J. Elec. Spec. Rel. Phen.<br />
1977, 12, 67-76.<br />
“<br />
89
JUNE 28 WEDNESDAY MORNING<br />
RIVA-SS-WeM-INV.1 STM STUDY OF MODIFICATIONS ON VACUUM FIRED 304L<br />
STAINLESS STEEL SURFACES. M. Leisch and A. Stupnik. Institute for Solid State Physics,<br />
Graz University of Technology, Petersgasse 16, 8010 Graz, Austria<br />
In UHV and XHV applications high temperature bakeout (vacuum firing) is a common method to reduce<br />
the hydrogen outgassing rate from stainless steel surfaces. This procedure reduces the amount<br />
of hydrogen in the bulk. At low bulk concentration hydrogen, outgassing is basically limited by surface<br />
recombination.<br />
The surface of glass bead blasted 304L steel samples was investigated by STM after normal bakeout<br />
procedure at 300°C and after vacuum firing at 1000°C. During vacuum firing a complete reconstruction<br />
of the surface can be observed. Already after 5 min of vacuum firing the formation of (111) terraces<br />
with monoatomic steps can be found. Slightly tilted crystallites exhibit (111) terraces intersected<br />
by bunched steps and facets. These facets form a nearly regularly pattern corresponding in<br />
orientation almost to the (100) and (110) planes. After 15 min vacuum firing large (111) terraces<br />
with extensions up to 200nm intersected by bunched steps can be observed. The general appearance<br />
of the surface after vacuum firing indicates a significant reduction of active sites for recombination<br />
of hydrogen. This supports the present understanding of outgassing for this material.<br />
Supported by „Zukunftsfonds des Landes Steiermark“<br />
88
RIVA-SS SESSION<br />
87
JUNE 28 WEDNESDAY MORNING<br />
WeM-Pl.3 FUNCTIONAL CERAMIC THIN FILMS, NEW MATERIALS FOR THE<br />
FUTURE, FROM NATURALLY NANOLAMINATED MAX-PHASES TO TAILORED<br />
NANOCOMPOSITES OF CARBIDES, OXIDES AND NITRIDES. H. Högberg, Thin Film<br />
Physics Division, Department of Physics (IFM), Linköping University, SE-58183 Linköping, Sweden.<br />
There is a strong desire to design a material with properties that match the demands foreseen in future<br />
applications. Thus, the development of functional materials is gaining increased attention in materials<br />
science today. This presentation focuses on two such highly promising branches of functional<br />
thin films, namely the layered ternary ceramic compounds known as the M n+1 AX n (n=1-3) phases,<br />
where M is an early transition metal (Ti, Nb), A is a group 13-15 element (Al, Si, Ge), and (X) is either<br />
C or N, and nanocomposites from the TiC/SiC, TiN/SiN x and ZrO 2 /Al 2 O 3 systems. A limited<br />
miscibility for one of the constituents is inherent to all of these systems, which causes segregation of<br />
the element during synthesis. For the MAX phases, typically synthesized as bulk materials at temperatures<br />
of ∼1300 o C, the process yields an anisotropic crystal structure in which MX blocks are interleaved<br />
by pure A-element layers. This nanolaminated structure give rise to the unique set of properties<br />
for these materials as reported by Barsoum et al. Typically the MAX phases show high oxidation<br />
resistance in combination with good thermal and electrical conductivities. These attributes are<br />
also ideal for advanced thin film applications were multi-functionality is required at elevated temperatures<br />
and/or harsh environment. Recently, we have developed dc magnetron sputtering processes<br />
for the growth of MAX-phase thin films from the systems Ti-A-C, A=Al, Si, Ge, or Sn, using either<br />
growth from elemental sources or Ti 3 SiC 2 and Ti 2 AlC (MAXTHAL®) targets. The processes enables<br />
the growth of epitaxial thin films on Al 2 O 3 (0001) substrates at substrate temperatures in the region<br />
700-1000 o C, including known bulk phases such as Ti 2 GeC, Ti 2 SnC, Ti 3 SiC 2 , and Ti 3 GeC 2 as<br />
well as new phases Ti 4 SiC 3 , Ti 4 GeC 3 , and Ti 3 SnC 2 . Characterization with four-point probe resistivity<br />
measurements shows that our thin films are good conductors. Nanoindentation confirms the ductile<br />
deformation behavior of the MAX phases and reveals details on the formation of pile up.<br />
For the nanocomposite thin films from particularly the TiN/SiN x system the pioneering work by<br />
Vepřek et al has provided invaluable knowledge regarding the microstructure design of films with<br />
improved properties. Their studies show that increased hardness is only achieved when the secondary<br />
amorphous phase (SiN x ) form a 1-2 monolayer thick tissue around small (
PLENARY<br />
85
WEDNESDAY<br />
84
JUNE 27 TUESDAY AFTERNOON<br />
WS-18-TuA-INV.8 ADVANCED PROCESS AND EQUIPMENT CONTROL (APC/AEC)<br />
THROUGH FINE GAS ANALYSIS IN VACUUM SYSTEMS FOR SEMICONDUCTOR<br />
MANUFACTURING. Giuseppe FAZIO, ST Microelectronics - Italy<br />
In the Advanced Process and Equipment Control (APC/AEC) the studies and the evaluations related<br />
to new methodologies and new devices are considered key activities.<br />
In vacuum chamber the Optical Emission Spectroscopy (OES) and Residual Gas Analyzer (RGA)<br />
are two instruments consolidated and widely utilized due to their high performance and flexibility.<br />
OES<br />
RGA<br />
OES and RGA applications<br />
Main application<br />
Other application<br />
Process Control<br />
Equipment Control<br />
(i.e., End Point Detection) (i.e., finger print equipment)<br />
Equipment Control<br />
Process Control<br />
(i.e., leak detection)<br />
(i.e., degas step optimization)<br />
Also from APC/AEC point of view these two instruments (OES and RGA) and their various applicable<br />
methodologies (process and equipment control) have to be continuously developed.<br />
Some of our direct experiences concerning these aspects will be showed.<br />
OES example<br />
Optical emission spectroscopy (OES) is widely used to perform in situ characterization and plasma<br />
processing control, as for instance in dry etching end point detection.<br />
In current practice only UV-VIS range is used, which corresponds to electronic transitions of molecular<br />
or atomic levels.<br />
However, when areas to be patterned within the wafer are small, and etching selectivity is not well<br />
known, the OES could not be enough.<br />
To detect the optical end point a new portion of the spectra has been studied (corresponding to molecular<br />
vibrational modes) and its emission enhancement.<br />
RGA example<br />
When the pressure is lower than 10mTorr a miniature array of quadrupole mass spectrometers has<br />
been considered (Micropole sensor).<br />
This sensor has a small size and it is feasible to install it in a small volume, without loosing high performances,<br />
and turns out to be very flexible on applications.<br />
Recently an instrument for advanced diagnostic using the RGA Micropole has been developed.<br />
This instrument allows technicians to control the vacuum chambers in order to have higher accuracy<br />
and faster analysis, requirements more and more important for hi-tech industries like the semiconductor<br />
one.<br />
When the pressure is higher than 10mTorr the traditional RGA (quadrupole) requires pump system.<br />
For this reason the system is not suitable for industrial field: cumbersome and complicated from a<br />
maintenance point of view.<br />
Therefore, we have evaluated alternative instruments: ICP plasma source, analysis by OES of atomic<br />
and molecular emission due to plasma excitation of residual gases.<br />
Hardware malfunctions were simulated on etch equipment and the consequent behaviour of the<br />
plasma emission spectrum was analyzed in order to evaluate and quantify detectable differences.<br />
The installation of this type of sensor on Transfer Module of the metal etch tool has been planned for<br />
the detection in line for leakage and humidity. In particular the focus concerns the wet cleaning recovery<br />
after PM and the reduction of the possible particle contamination produced by humidity.<br />
83
JUNE 27 TUESDAY AFTERNOON<br />
WS-18-TuA-INV.7 THE DESIGN AND OPERATION OF THE JET VAC-<br />
UUM AND FUELLING SYSTEMS AND THEIR RELEVANCE TO ITER. R J<br />
H Pearce, Euratom-UKAEA Association, Culham Science Centre, Oxon, OX14 3DB.<br />
UK . M. <strong>Wykes</strong>, ITER IT, IPP, Boltzmannstr. 2, 85748 Garching, Germany.<br />
JET is the world largest magnetic confinement fusion device and the only device with the capability<br />
to operate with tritium. JET first operated in 1983 and since this time it has been regularly enhanced<br />
and upgraded. Agreement is now well advanced for building ITER at Caderache in France. JET has<br />
played a key role in the ITER design, in particular by operating in deuterium/tritium, by testing divertor<br />
designs, in developing first wall technology, by operating with high power heating systems<br />
and in consolidating ITER operating scenarios.<br />
The JET main vacuum vessel is of doubled walled construction of volume ~200m 3 and is capable of<br />
being baked to 320 o C. It is pumped by turbo-molecular pumps in addition to a high pumping speed<br />
cryogenic pump in the divertor region. Typically JET now operates at 200 o C with a base pressure in<br />
the 10 -8 mbar region. The total pressure is dominated by deuterium outgassing and by the vapour<br />
pressure of deuterium held on the supper critical helium cryogenic pumps. Impurity partial pressures<br />
are in the 10 -10 mbar region.<br />
The JET vacuum vessel and other vacuum containment system also act as the primary containment<br />
system for tritium injected or stored in the JET. This necessitates the need for high integrity on all<br />
boundary components and double containment on delicate components.<br />
The vacuum characteristic of JET are significantly affected by plasma facing components. These<br />
have been an important area of development and change in magnetic confinement fusion devices. On<br />
JET the vacuum vessel’s first wall has been regularly changed, progressing from inconel, to graphite,<br />
to the current carbon fibre composite (CFC). In addition various experiments with partial beryllium<br />
coverage have been performed. A full beryllium wall with a tungsten coated, CFC divertor is<br />
planned for the future as a reference for ITER.<br />
The physics programme on JET has lead to demanding requirements for the supply of gas to the torus.<br />
In particular the pumped divertor necessitates scenarios with high fuelling rates. In total 12 fuelling<br />
points are used. It is required to deal with large numbers of gas species, expensive gas species,<br />
reactive gas species as well as tritium gas. An automated system is used for introducing gas into JET.<br />
The system gives the flexibility for gases to be changed frequently without compromising gas purity.<br />
Three successful experimental tritium campaigns have been performed on JET. An initial tritium inventory<br />
of 20g has been used for a total injection, to date, of ~36g. The experiments have provided<br />
very valuable experience in complex systems on, tritium handling, retention and accounting. New<br />
challenges will however be encountered within the ITER fuel cycle with ~3Kg of tritium proposed to<br />
be on site and ~850Kg to be injected through the life of ITER.<br />
The design and operation main JET vacuum and fuelling systems are described. These are compared<br />
with the proposed systems for ITER. Where there is particular ITER relevant experience, in the design,<br />
manufacturing, and operation of vacuum and fuelling systems, this is highlighted.<br />
<strong>82</strong>
JUNE 27 TUESDAY AFTERNOON<br />
WS-18-TuA-INV.6 QUALITY CONTROL AND LEAK DETECTION IN LARGE VAC-<br />
UUM SYSTEMS. P. Chiggiato. CERN, European Organization for Nuclear Research. CH-1211<br />
Geneva 23, Switzerland.<br />
Large ultra-high vacuum systems can be jeopardized by the failure of a single vacuum component.<br />
As a consequence, a careful choice of materials, assembling techniques and surface treatments is<br />
mandatory in order to avoid leaks (both real and virtual) and excessive outgassing that could spoil<br />
the efficiency of the pumping system. However, even if the suitable choice of the production procedure<br />
is taken, a dedicated quality control plan is essential to avoid the result of clumsy operations<br />
and drifts in the production parameters.<br />
For the Large Hadron Collider (LHC), which is under construction at CERN and expected to run at<br />
the end of 2007, thousands of vacuum components are being produced and different quality control<br />
programs are applied. For the particular case of the about 1200 long straight section (LSS) vacuum<br />
chambers, the quality insurance program will be reviewed by taking into account the most critical<br />
steps of the production procedure, namely extrusion of the OFS tubes, vacuum brazing of the<br />
flanges, TIG welding, chemical treatment of the inner surface, and deposition of the Ti-Zr-V nonevaporable<br />
getter (NEG) thin film. Several characterization techniques are involved, for example X-<br />
ray radiography, optical and metallurgical analysis, leak detection, surface sensitive inspection (XPS<br />
and AES) and non-traditional vacuum measurements.<br />
The quality control plan continues also after the installation of the components in the accelerator ring<br />
or into complex devices like superconducting magnets and distributing field boxes. In this context,<br />
the validation criteria for the NEG film activation process in the LSS will be presented. In addition,<br />
an alternative method for detecting leaks in the complex cryogenic lines of the superconductive<br />
quadrupoles of the LHC will be described.<br />
In order to save and to simply retrieve the massive quantity of data coming from the different controls,<br />
a dedicated software has bee developed at CERN; for most of the components installed in the<br />
main ring, it allows the tracking of all the production and control reports together with the actual position<br />
in the accelerator.<br />
81
WS-18 SESSION<br />
80
JUNE 27 TUESDAY AFTERNOON<br />
JS1 SESSION<br />
ROUND TABLE<br />
CHAIRMAN: J. M. ALBELLA ICMM-CSIC-ES<br />
PRESENTERS:<br />
A. CAVALEIRO UNIVERSITY OF COIMBRA. PT<br />
J.A. GARCÍA AIN, ES<br />
F, ORGAZ MEC.ES<br />
79
JUNE 27 TUESDAY AFTERNOON<br />
JS1-TuM-INV.12 MICROFABRICATION BY DIRECT WRITING ON DIELECTRICS<br />
USING ULTRASHORT LASER PULSES. J. Solis, Instituto de Optica, CSIC, Serrano 121, E-<br />
28006 Madrid, SPAIN<br />
Subsurface modification of transparent materials with femtosecond laser pulses is a promising tool<br />
for the fabrication of 3-D photonic elements. However, in spite of its successful application to the<br />
production of waveguides and other photonic elements such as gratings, waveguide amplifiers, or<br />
photonic band-gap structures in a variety of dielectric materials, its widespread use is still hampered<br />
by several problems related to the control of energy deposition inside the dielectric material. The<br />
presence of spherical aberrations, as a consequence of the refractive index mismatch at the airdielectric<br />
interface, as well as non-linear propagation phenomena have already been identified as<br />
critical issues, very particularly in high refractive index materials. The presentation will provide an<br />
overview of the fundamentals of this processing technique as well as different strategies aimed either<br />
at better controlling the energy deposition inside the material or at producing functional photonic<br />
elements in “difficult” materials like heavy metal oxide glasses.<br />
78
JUNE 27 TUESDAY AFTERNOON<br />
JS1-TuA-INV.11 SURFACE FUNCTIONALIZATION OF CERAMIC TILES BY<br />
NOVEL DESIGN TECHNIQUES (PLASMA, INK JET, ETC.) J. Ribera, Invest Plasma S.L.<br />
Poligono Estadio, Nave 34. 12004 Castellon. J. Carda, Inorganic and Organic Chemistry dept, Campus<br />
Riu Sec, Universitat Jaume I. 12080 Castellón<br />
Spanish ceramic industry is one of the major world producers of ceramic tiles reaching annual production<br />
volume of more than 600 million m 2 . Nevertheless currently high competition by other countries<br />
can be observed. This makes necessary to introduce higher added value to the products, creating<br />
new functionalities. One of the important areas of interest in near future is surface treatment with the<br />
use of nanoparticles and thin-film technology and new processes in order to obtain functionally new<br />
products with higher added value. In this respect a review of the traditional decorative techniques for<br />
ceramic tiles, indicating the new possibilities of plasma-coating of metal and oxide coatings and laser<br />
treatment with decorative purposes in order to create desired colour in situ. As well the ink jet technologies<br />
and development of new nanoparticulate pigments development in the will be highlighted.<br />
77
JUNE 27 TUESDAY AFTERNOON<br />
JS1-TuA-INV.10 DECORATIVE COATINGS ON ENAMEL CERAMICS DEPOS-<br />
ITED BY PVD TECHNIQUES. A. Alberdi. Fundación Tekniker. Avda. Otaola, 20. 20600<br />
Eibar, Spain..F. Lucas, A. Belda. Fritta S.L. CV-20 Km 8, 12200 Onda (Castellón), Spain.Mª<br />
José Orts. Instituto de Tecnología Cerámica (ITC). Campus Universitario Riu Sec, 12006 Castellón,<br />
Spain<br />
Ceramic tiles - floor tiles, wall tiles and other decorative articles - are usually made by firing a ceramic<br />
backing, which is coated with a consolidated layer of frits and crystalline materials that glaze<br />
after the baking process. The ceramic backing may be raw, as when the single-fire method is used,<br />
or else baked, when the double-fire method is used.<br />
Obviously, ceramic glazed products must have technical and decorative qualities that make them<br />
suitable for the use to which they are to be put, such as hardness, resistance to cracking, wear and<br />
scratching, imperviousness and insolubility in water and in those acids and alkalis with which they<br />
may enter into contact in normal use. Decorative effects are created depending on the finishing<br />
process used, for example, gloss or matt, opaque or transparent, smooth or granulated, polished, etc.<br />
Modern decorative trends ask for conferring the tile a metallic appearance.<br />
Current ceramic metallizing techniques normally consist of adding a given amount of metal to the<br />
baked tiles, but prior to glazing or final enamelling, so their finishes have very low scuff and<br />
scratching resistance, being impossible to use on floors or facades, and they are not resistant to<br />
chemical attack. Furthermore, the gloss of current finishes does not exceed 200‰ at angle of incidence<br />
of 60º.<br />
Recently, new metallizing techniques have been developed using Physical Vapour Deposition<br />
(PVD) methods. The authors set up a novel procedure to metallise enamelled products. Under vacuum<br />
and after degassing the tile backing, a metallic coating grows on the enamelled tile surface by<br />
bombardment with metallic ions and neutral atoms of titanium, zirconium, tantalum or chromium.<br />
These atomic species are generated by a high intensity arc discharge (in the range 50-250 A) between<br />
an electrode made of the metal of interest, normally a rod, pipe or plate, and an auxiliary cooper<br />
electrode. Apart from pure metal films, nitrides and carbo-nitrides of these metals can be also<br />
deposited on the tile surface by adding nitrogen and hydro carbide gases in the vacuum chamber.<br />
Using this new procedure, enamelled tiles coated with 0.3 microns thick decorative films were produced,<br />
which show attractive colours and metal appearance. Finishing colours depended on the<br />
chemical nature of the film: golden (zirconium, titanium and tantalum nitrides), metallic grey (chromium<br />
nitride, and pure Ti, Zr or Cr), reddish brown or purple (titanium carbo-nitrides). Apart from<br />
the attractive colour, these decorative surfaces exhibit an outstanding metallic gloss (ZrN 736‰ at<br />
angle of incidence of 60º), and excellent resistance to acids and alkaline substances.<br />
Key words: Ceramic tiles, decorative coatings, physical vapour deposition.<br />
.<br />
76
JUNE 27 TUESDAY AFTERNOON<br />
JS1-TuA-INV.9 HARD DECORATIVE METAL-OXYNITRIDE THIN FILMS PRE-<br />
PARED BY PVD. F. Vaz, P. Carvalho.Departamento de Física, Universidade do Minho, 4800-058<br />
Guimarães, Portugal.<br />
The main objective of this work is the preparation of decorative zirconium oxynitride, ZrO x N y , thin<br />
films by dc reactive magnetron sputtering. Film properties were analyzed as a function of the reactive<br />
gas flow and were correlated with the observed structural changes. Measurements showed a systematic<br />
decrease in deposition rate with the increase of the reactive gas flow and revealed 3 distinct<br />
modes: i) metallic mode, ii) a transition mode and iii) an oxide mode. The measurements of target<br />
potential were also consistent with these changes, revealing a systematic increase from 314 to 337 V.<br />
Structural characterization uncovered different behaviors within each of the different zones, with a<br />
strong dependence of film texture on the oxygen content. These structural changes were also confirmed<br />
by resistively measurements, whose values ranged from 250-400 cm for low gas flows<br />
and up to 10 6 cm for the highest flow rates. Color measurements in the films revealed a change<br />
from bright yellow at low reactive gas flows, to red-brownish at intermediate flows and dark blue for<br />
films prepared at the highest flows. Hardness measurements gave higher values for the region where<br />
larger grain sizes were found, showing that the grain growth hardening effect is one of the main parameters<br />
that can help explain the observed behavior. Also the peak intensity ratio and the residual<br />
stress states were found to be important factors for explaining this behavior.<br />
75
JS1 SESSION<br />
74
TUESDAY AFTERNOON<br />
73
JUNE 27 TUESDAY MORNING<br />
WS-18-TuM-OR.10 A NEW PROCEDURE AND DEVICE FOR THE STUDY OF HY-<br />
DRIDING PROCESSES FROM THE INNER SURFACE OF NUCLEAR FUEL CLAD-<br />
DINGS. M. Díaz a , J. S. Moya a , J. L. Sacedón a* a Instituto de Ciencia de Materiales de Madrid<br />
(CSIC), Cantoblanco, Madrid-28049, Spain. B. Remartínez b , S. Pérez b . b TEMAT Iberdrola, Pº<br />
Virgen del Puerto, Madrid-28005, Spain<br />
A new method and UHV equipment 1,2 that allows the study of the hydriding process of fuel claddings<br />
from the inner surface is described. The hydriding is performed by heating the cladding in an<br />
ultra-high vacuum chamber while hydrogen flows inside the tube. The external H 2 partial pressure,<br />
the tube electrical resistance and the power dissipated by the reaction are measured throughout the<br />
process. These measurements at different hydriding stages are complemented with an optical microscopy<br />
analysis of the claddings give insight into the main physical processes 1 . As a consequence a<br />
description of the hydriding first stages is provided. The method allows the measurement of the incubation<br />
and failure times and the total energy dissipated by the hydriding reaction. In addition, useful<br />
information about the kinetics of the hydriding process is obtained from external H 2 partial pressure<br />
vs hydride rim thickness plot<br />
This method has been applied to test the durability and reliability against the hydriding reaction of<br />
commercial fuel claddings of zirconium alloys with different compositions and thermal treatments.<br />
An additional study of the variation of Vickers hardness and elastic modulus with the stoichiometry<br />
and thickness of the zirconium hydride rim formed inside this type of claddings has been carried out<br />
by nanoindentation and XRD measurements. From these results it is possible to obtain some conclusions<br />
about the mechanical stress distribution induced by the hydriding process and its influence in<br />
the failure of these industrial elements.<br />
1 Patent No.: US 6,873,672 B2<br />
1 Patent No.: WO 2005/076286 A1<br />
1<br />
J. L. Sacedón, M. Díaz, J. S. Moya, B. Remartínez, J. Izquierdo, Journal of Nuclear Materials, 327 (2004) 11-18.<br />
72
JUNE 27 TUESDAY MORNING<br />
WS-18-TuM-OR.9 CALIBRATION OF HELIUM LEAKS: REFERENCE METHOD<br />
AND DISSEMINATION. RANGE FROM 4.10 -14 MOLE.S -1 (10 -10 PA.M 3 .S -1 ) TO 4.10 -6<br />
MOLE.S -1 (10 -2 PA.M 3 .S -1 ). Pierre OTAL, Frédéric BOINEAU, Jean-Claude LEGRAS. Laboratoire<br />
National de Métrologie et d’Essais (LNE)<br />
LNE developed in the last years a new method for the calibration of helium leaks. It is based on the<br />
measurement of the pressure variation p due to the flow rate of the leak in a known volume. The<br />
pressure is measured using a capacitance diaphragm gauge starting at about 3 Pa. A capillary leak is<br />
calibrated as a function of the input pressure for both helium and nitrogen. The pressure variation allows<br />
to creating a flow range over a decade.<br />
Then the leak is supplied with mixtures of helium in nitrogen at different known concentrations<br />
down to 100 ppm. The flow rate of helium is calculated from the total flow measured by the p and<br />
the concentration measured in the LNE gas analysis laboratory. Different combinations of input<br />
pressure and concentrations allow to defining step by step the flow scale down to 4.10 -14 mole.s -1 .<br />
An uncertainty budget will be presented. The estimated uncertainty is ranged from 2 % at 4.10 -6<br />
mole.s -1 to 5.5 % at 4.10 -14 mole.s -1 . Two methods are used for disseminating the measurements to<br />
industry:<br />
- A method by substitution, where the helium leak so defined is used to reproduce the same<br />
output signal of a leak detector as observed with a working reference leak.<br />
- A direct measurement of the client helium leak using the output signal of the leak detector.<br />
In that case, the output signal is fitted as a function of the leak over 3 decades using 5 helium<br />
leaks firstly calibrated.<br />
Some results related to the linearity and the reproducibility of the leak detector will be given.<br />
A comparison with another calibration technique developed for the low gas flow measurement has<br />
been carried out in the higher part of the range. The agreement between the two methods operating<br />
under vacuum for the first one and near the atmosphere for the other one was about 1 %, inside the<br />
estimated combined uncertainty.<br />
71
JUNE 27 TUESDAY MORNING<br />
WS-18-TuM-OR.8 CURRENT TRENDS IN LEAK TESTING TECHNOLOGY<br />
A. P. Fonseca, H. P. Marques, A. M. C. Moutinho and O. M. N. D. Teodoro. METROVAC – Laboratório<br />
de Tecnologia e Metrologia de Vácuo. CEFITEC, Departamento de Física, Faculdade de<br />
Ciências e Tecnologia, Universidade Nova de Lisboa, 2<strong>82</strong>9-<strong>51</strong>6 CAPARICA, Portugal<br />
Leak detection techniques are not of exclusive use of the vacuum scientist but are increasingly taking<br />
their place in the demanding industrial environment. Accordingly, the definition of what is a leak<br />
must also evolve to accommodate the points of view of the industry. A leak always involves a flow<br />
of mass though the walls of a vessel. It usually results in an escape of liquids, vacuum or gases from<br />
sealed components or systems.<br />
Due to the demands of the electronics industry and increased activities in space exploration, the need<br />
to develop new equipments and devices that had to be free of significant leakage appeared.<br />
The maximum acceptable leak rate for a given product depends upon the nature of the product. In a<br />
compact electronic device, like a photon multiplier, with a size of 2 cm 3 even a leak rate of 10 -<br />
10 mbar l s -1 will be too high, producing a lifetime of only about 7 hours!<br />
Leak detectors range in complexity from a tank of water, in which bubbles from a leak can be seen,<br />
to highly sophisticated systems using radioactive tracer gases, depending on the leak detection technique<br />
– e.g. acoustics, hydrostatic test, tracer fluids or gases, high voltage discharge. However, is the<br />
application that defines the most appropriated method.<br />
Commercial helium mass spectrometer leak detectors can commonly detect leaks down to 10 -10<br />
mbar.l.s -1 range. Lower rates can appear from molecular permeation and not from orifices and therefore<br />
are difficult to distinguish.<br />
High sensitivity in commercial leak detectors is longer the most demanded requirement. Most developments<br />
are being made in order to miniaturize the detectors as well as to fully automate its operation.<br />
It has been developed a miniature mass spectrometer [ref MKS] with dimensions of<br />
30x30x15 cm and weight less than 8 kg. With this kind of portable detectors it’s less time-consuming<br />
to detect leaks in large vacuum systems that often require access to a great number of test points.<br />
The latest published papers favour developments in acoustics detection technology for example Holland<br />
et al describes a method for in-orbit identification and location of a leak in the International<br />
Space Station using structure-borne ultra-sonic noise.<br />
In this paper is work we summarize the most suitable leak detection methods according to the application<br />
and the maximum admissible leak rate.<br />
70
JUNE 27 TUESDAY MORNING<br />
WS-18-TuM-OR.7 HEALIUM LEAKS TRACEBILITY AT CZECH METROLOGY<br />
INSTITUTE (CMI). Dominik Prazak. Czech Metrology Institute, Okruzni 31, 638 00, Brno,<br />
Czech Republic. Jiri Tesar. Czech Metrology Institute, Okruzni 31, 638 00, Brno, Czech Republic.<br />
Petr Repa. Charles University Prague, V Holesovickach 2, 180 00, Prague 8, Czech Republic.<br />
Ladislav Peksa. Charles University Prague, V Holesovickach 2, 180 00, Prague 8, Czech Republic.<br />
Tomas Gronych. Charles University Prague, V Holesovickach 2, 180 00, Prague 8, Czech Republic.<br />
Martin Vicar. Czech Metrology Institute, Okruzni 31, 638 00, Brno, Czech Republic.<br />
The tightness of vacuum systems has very high and increasing importance in contemporary research,<br />
industry and safety of work. Its consequence is continuous and growing demand for the calibration<br />
services in this field.<br />
Mass spectrometers as helium leak detectors are traditionally used for accurate measurement of vacuum<br />
leaks. The critical point of their accuracy is their low long-term stability. It is necessary to calibrate<br />
them with very short recalibration periods utilizing the secondary helium leak standards. But,<br />
of course, these secondary standards need the traceability to the standards of higher order. Until recently,<br />
CMI has used the services of other national metrological laboratories, but this system has<br />
been becoming more and more insufficient.<br />
So there has been decided to build our own primary standard of vacuum leaks in the framework of<br />
United vacuum laboratory of CMI and Charles University – Prague. The recently finished high vacuum<br />
standard based on continuous expansion has been chosen as the base leading to the reduction of<br />
costs. That implies use of constant pressure - variable volume flow meter and comparative measurement<br />
method. Its preliminary range is 3 . 10 -7 - 7 . 10 -4 Pa . m 3. s -1 with uncertainty less than 0.5 %, but we<br />
study the possibilities of its extending. First of all it is needed in the lower range limit.<br />
The paper will describe the problems that have occurred during construction (flow meter based on<br />
bellows, its compression mechanism and measurement, reproducibility of its volume, pressure and<br />
temperature stabilization and measurement, parasitic effects), the method of traceability and the attainable<br />
uncertainties.<br />
[1] ŘEPA, P., TESAŘ, J., GRONYCH, T., PEKSA, L., WILD, J.: Analyses of gas composition in<br />
vacuum systems by mass spectrometry. Journal of Mass Spectrometry. 2002 (37), p. 1287-<strong>129</strong>1.<br />
[2] PEKSA, L., GRONYCH, T., ŘEPA, P., TESAŘ, J.: Measuremet of the pressure differences in a<br />
large chamber where the pressure is generated dynamically. Vacuum. 2002 (67), p. 333-338.<br />
[3] PEKSA, L., ŘEPA, P., GRONYCH, T., TESAŘ, J., PRAŽÁK, D.: Uncertainty analysis of the<br />
high vacuum part of the dynamic flow standard. Vacuum. 2004 (76), p. 477-489.<br />
69
JUNE 27 TUESDAY MORNING<br />
WS-18-TuM-OR.6 LEAK CALIBRATION BY COMPARISON WITH REFERENCE<br />
STANDARD LEAKS. J. M. Hidalgo * and J. L. de Segovia ** * Telstar Industrial S. L., José Tapiolas<br />
120, Tarrasa, Spain. ** Instituto de Ciencia de Materiales, CSIC, Cantoblanco, 2<strong>82</strong>49 Madrid,<br />
Spain.<br />
e-mail: jldesegovia@icmm.csic.es/j.mhidalgo@telstar.es<br />
For an industrial calibration laboratory the faster and reproducible method for helium leak calibration<br />
is by comparing the leak to be calibrated with standard leaks already calibrated at a National<br />
Calibration Laboratory or Accredited Laboratory, using a mass spectrometer tuned to Helium gas. In<br />
the present work all the possible sources of uncertainties are discussed and they relative contributions<br />
presented. Special consideration is given to the problem of the long term satiability contribution.<br />
The optimal capacity of measurement is obtained according to the results obtained by application<br />
of the specific calibration procedure.<br />
68
JUNE 27 TUESDAY MORNING<br />
WS-18-TuM-INV6.5 LEAK DETECTION: CALIBRATIONS AND REFERENCE<br />
FLOWS ARE REQUIRED IN EVERY TYPE OF APPLICATIONS: PRACTICAL EXAM-<br />
PLES. A.Calcatelli, Istituto Nazionale di Ricerca Metrologica, I.N.RI.M., Turin, Italy.M.Bergoglio,<br />
Istituto Nazionale di Ricerca Metrologica, I.N.RI.M., Turin, Italy<br />
D. Mari, Istituto Nazionale di Ricerca Metrologica, I.N.RI.M., Turin, Italy<br />
Several methods and related instrumentation are used for leak detection from bubble emission to the<br />
ultrasound devices, to pressure/vacuum variation measurements (vacuum gauges, thermal conductivity<br />
sensors), to halogen leak detectors or detectors using radioisotopes, to the more recent instruments<br />
based on selective ion pump detection (SIPD) and finally to the application of mass spectrometry.<br />
The most diffused methods for the leak rates lower than 10 -3 Pa m 3 /s that is based on the<br />
application of mass spectrometry with tracer gas (generally helium) is considered (MSLD). MSLD<br />
represents the best choice for industrial control of tightening for its good sensitivity and obtainable<br />
speed of testing. The leak test may be performed with various methodologies (vacuum, pressure or<br />
vacuum-pressure) and its purpose may be to localize the leaks or to quantify them.<br />
Leak detection is considered, at European level, by the WG 6 (leak testing) of the CEN/TC 138 (Non<br />
Destructive Testing), and worldwide level by the SC 6 “Leak detection methods” of the ISO/TC 135<br />
(Non Destructive Testing). At European level, several standards have been published regarding terminology<br />
as well as the choice of the method or the calibration of a leak detector and calibration of<br />
standard leaks.<br />
If the leak detector output must have a real meaning in term of gas flow-rate the instrument has to be<br />
calibrated and its uncertainty must be evaluated. Therefore, the calibration of a leak detector is performed<br />
with reference to known gas flow-rates by using the so-called standard leaks both of permeation<br />
or geometrical type (generally capillaries) which are used to generate flow from 10 -9 Pa m 3 /s<br />
to 10 -3 Pa m 3 /s; these standard leaks are calibrated with reference to atmospheric pressure or vacuum<br />
against primary gas flow-meters. The I.N.RI.M. primary flowmeters are shortly described which<br />
cover the following gas flow-rate ranges:<br />
• 2.10 -9 Pa m3/s e 2x10 -8 Pa m 3 /s with reference to vacuum, extended uncertainty 8%<br />
• 2x10 -8 - 3.10 -5 Pa m 3 /s with reference to vacuum, extended uncertainty from 2% to 0.5%.<br />
• 2.10 -5 Pa m 3 /s e 1.10 -3 Pa m 3 /s with reference to atmospheric pressure, extended uncertainty 2%.<br />
Some calibration results are presented together with the preliminary results of a bilateral comparison<br />
which is considered as preparatory for a more wide scale comparison.<br />
A device devoted to on line control of components which need that all the significant parameters be<br />
well defined starting from the mass spectrometer leak detector which is characterized from metrological<br />
point of view, that is to say essentially for what concerns linearity and repeatability of the<br />
out-put by using reference leaks. The whole machine must be well known in its working configuration<br />
for what concerns linearity and repeatability and the traceability chain must be made evident.<br />
67
WS-18 SESSION<br />
66
JUNE 27 TUESDAY MORNING<br />
JS1-TuM-INV.8 ADDED VALUE NANOSTRUCTURED COATINGS WITH TAI-<br />
LORED OPTICAL BEHAVIOUR. C. N. Afonso. Instituto de Optica, CSIC, Serrano 121, 28006<br />
Madrid, Spain.<br />
Optical coatings are generally formed by multilayer films whose spectral transmission / reflection are<br />
typically controlled through the number of layers, their refractive index and their thickness. However,<br />
current applications demand more functionalities such as selective operation depending on input<br />
conditions (intensity, polarization, etc...), tuneable or ultrafast response, and in many cases, several<br />
functions in the same coating. The design of the structure of the coating in the nanoscale is an<br />
attractive route to achieve this goal.<br />
This presentation aims to show examples on how nanostructuring allows tailoring the properties of<br />
the film or coating to the desired applications. It will first be illustrated through the production of<br />
nanocomposite materials formed by metal nanoparticles embedded in a dielectric host that are known<br />
to exhibit optical resonances due to dielectric or classical confinement effects. These effects are responsible<br />
for colouring of many decorative glasses when the dimensions of the nanoparticles are<br />
much smaller than the wavelength of the light. Whereas bulk techniques usually disperse nanoparticles<br />
randomly, thin film technologies offer the possibility of organising nanoparticles in layers. This<br />
layered structure can be then designed in order to achieve the desired response. This concept can<br />
straightforwardly be extrapolated to other “dopants” such as ions or different hosts such as glasses or<br />
ceramics. Examples will be given on how the optical response of nanocomposite films /coatings can<br />
be tuned through the dimensions and separation of the nanoparticles, their “layered” distribution or<br />
the use of different hosts. Finally, the possibility of incorporating different functionalities in the same<br />
coating either through the use of different “dopants” or pairs “dopants”-host will be illustrated.<br />
65
JUNE 26 TUESDAY MORNING<br />
JS1-TuM-INV-7 COATINGS FOR OPHTHALMIC LENSES. T. Vilajuana, Departamento<br />
de I+D+I INDO, Sta. Eulàlia, 181 08902 L’Hospitalet de Llobregat, Barcelona. Spain. E-mail:<br />
toni@indo.es<br />
Since 1937 Indo is the leading company in the ophthalmic optics Spanish market, and one of the five<br />
main European companies of the sector. The core activity of the company is the fabrication of spectacle<br />
lenses, which represents more than 50% of the total turnover. The investment in R&D activities<br />
was 2.5% of the sales income in 2005 and is planned to increase an additional 4% in 2006.<br />
The main requirements of an ideal ophthalmic lens, are lightness, transparency, scratch resistance<br />
and impact strength. Additionally, an ideal lens should be as thin as possible. Organic or polymeric<br />
lenses have a clear advantage in terms of weight and impact resistance when compared to mineral<br />
glass. Nevertheless, a polymeric lens can be more easily abraded than a mineral one. Particularly,<br />
high refractive organic lenses can easily be scratched. For this reason, the application of anti-scratch<br />
coatings has become necessary to increase the abrasion resistance of polymeric lenses. Typically, that<br />
coating is a few micron layer of a composite based on a polysiloxane matrix containing silica<br />
nanoparticles. This provides the required flexibility and toughness to obtain good scratch resistance<br />
and optimum adhesion of the coating to the lens.<br />
An additional benefit of some lenses is that they adapt to light conditions, changing its transmittance<br />
according to the amount of light outdoors. The benefit of this photochromic lenses is that they provide<br />
a dynamic adaptation to light conditions and a UV protection. This is due to the presence in the<br />
lens of molecules that react with UV radiation. The absorption of UV radiation changes the molecule’s<br />
steric configuration, and consequently absorbing visible light. This is why the lens becomes<br />
dark brown or grey, etc. This process is reversible and in the absence of UV light, the lenses become<br />
clear. Some polymer lenses are casted mixing these photochromic molecules with the lens monomer,<br />
while others are applied a photochromic layer in the external surface of a clear lens.<br />
Lenses reflect light, since they consist of two optical surfaces that are immersed in an environment of<br />
different refractive index. The higher the difference, the more light is reflected. This light reflected is<br />
perceived as ghost images that superpose to natural perception and reduce the quality of vision,<br />
which contributes to increase fatigue. These reflections can be practically be reduced with the application<br />
of an antireflective (AR) coating, typically composed of 5 to 7 layers of metal oxides.<br />
The first AR coatings easily got dirty and the smudges and fingerprints were more visible and difficult<br />
to remove. In fact, many patients found it difficult to keep clean. The application of a hydrophobic<br />
and oleophobic topcoat is a big advantage for these lenses, since they stay cleaner longer than<br />
previous ones. The composition of that layer is based on a mixture of perluorated hydrocarbons and<br />
silica compounds that repeal water and grease.<br />
Since lenses are produced in large quantities, additional concerns like uniformity of optical and mechanical<br />
properties are important key factors in order to decide which technology is used to produce<br />
these coatings. Lens reflectance, abrasion resistance, coating durability, hydrophobicity and photochromism<br />
has to be tightly controlled.<br />
Developing new polymer materials with better optical and mechanical properties requires the application<br />
of complex coatings and technologies. The production of millions of them at a competitive<br />
cost and in a personalised basis is the challenge of the leading ophthalmic optical companies.<br />
64
JUNE 27 TUESDAY MORNING<br />
JS1-TuM-INV.6 SMART OPTICAL WINDOWS OF VARIABLE TRANSPARENCY. E.<br />
Matveeva, Universidad Politécnica de Valencia (UPV), Centro Materiales y Tecnologías de Micro<br />
Fabricación (MTM), Unidad Asociada al Instituto de Ciencias de Materiales de Madrid, Cami de<br />
Vera s/n, E-46022 Valencia, España<br />
The rare earth metals as well as its alloys with magnesium, or proper magnesium alloyed with iron,<br />
nickel, manganese, etc. while being put into the contact with hydrogen form metal hydrides which<br />
are wide-band semiconductors transparent in visible range of electromagnetic spectrum. Reversibility<br />
of hydrogenation reaction allows for fabrication of the so-called Smart Optical Windows (SOW) that<br />
change their reflectivity in function of external impact (application of electric field, change of intensity<br />
of external light, change of temperature, etc.). The two approaches presently existed are hydrogenation<br />
of alloys in gas phase and in liquid phase. The first process is performed in pure H 2 and allows<br />
for achieving a long life-time, mere contrast of reflecting/transparent states and fair reproducibility<br />
of results. However, it would need pumping the hydrogen in and out to the chamber where hydrogenating<br />
metal is contained. Second approach is related with hydrogenation of alloys in liquid<br />
phase under the cathodic bias. Alkaline solutions are mainly used as electrolytes for hydrogenation<br />
(typically 1-6M KOH). This is due to the fact that those metals which possess hydrogenation ability<br />
are stable at high pH values, while neutral or acid electrolytes provoke their fast oxidation. Examples<br />
of electrochemical behavior of different hydrogenated materials will be demonstrated during the talk<br />
together with the optical transformations accompanied the hydrogenation/ dehydrogenation processes.<br />
The generalized design of the SOW with an electrical control consists of the two thin film electrodes<br />
and a conducting media between them. The whole system must be sealed to assure functional stability<br />
and integrity of the device similarly to devices used liquid crystals. One of the electrodes (principal)<br />
is hydrogenated and another is the transparent auxiliary electrode that mainly serves as a means<br />
to apply the potential. Due to limitations toward the electrolytes demonstrated by the principal electrode<br />
(basic conductive media) the second auxiliary electrode must work at the same conditions: immersed<br />
in 1-6M KOH. Indium-tin-oxide (ITO) gave firstly the impression to be a suitable candidate<br />
for an auxiliary electrode in SOW. Nevertheless, its proper electrochemistry in basic electrolytes<br />
governed by the mobility of the structural oxygen ions, deep reduction and changes in composition<br />
and conductivity make the SOWs fabricated with ITO as an auxiliary electrode not reliable. Other<br />
approaches to make conductive a transparent surface (glass/polymer) and exploit possibilities to fabricate<br />
a sandwich-type device are analyzed.<br />
In more advanced SOW technology the use of the polymeric conductive media has been demonstrated.<br />
Nowadays, the polymeric electrolytes (or conductive ionic membranes) have extended applications<br />
in hydrogen production, separation technologies and electrochemical synthesis. The key point<br />
in the conductive polymers (membranes) is the formation of the highly extended and penetrated network<br />
of the conductive nano-metric ionic passes formed from the overlapped solvated (hydrated)<br />
shells of the functional (acid) groups attached to the polymer chains. The dual character of the resulted<br />
material (consistency of polymer and conductivity of electrolyte) offers new options in SOW<br />
fabrication. The device implemented the Nafion membrane soaked in water and other solvents<br />
showed an acceptable working voltage, good transition to the transparent state and satisfactory lifetime<br />
under cycling.<br />
The principal sources for instability and device destruction are discussed based on the experience acquired<br />
in the MTM Center of the UPV.<br />
63
JUNE 27 TUESDAY MORNING<br />
JS1-TuM-INV.5 TAILORING THE OPTICAL PROPERTIES OF THIN FILMS DE-<br />
POSITED BY PLASMA CVD. A. Barranco, A. Borrás, F. Gracia, A.R. González-Elipe. Instituto<br />
de Ciencia de Materiales de Sevilla (CSIC-Universidad de Sevilla), c/Américo Vespucio s/n 41092<br />
Sevilla Spain.<br />
Plasma Enhanced Chemical Vapour Deposition (PECVD) and plasma treatments are being increasingly<br />
used for the fabrication of optical films and coatings. The technique offers a wide ranging control<br />
of plasma surface interactions, high deposition rates and conformal depositions being fully compatible<br />
with the existing silicon based semiconductor technology and scaleable from the laboratory to<br />
the industry. These materials are obtained in the form of single thin films, multilayers, graded index<br />
layers, nanocomposites, patterns, and others for applications such as optical filters, antireflective<br />
coatings, optical waveguides, wavelength shifters, optical sensors, etc. For these applications is critical<br />
the control of the chemical composition and the microstructure of the deposited films.<br />
Novel methodologies for the synthesis of optical thin films using plasmas will be presented. The examples<br />
cover the control of n and k values in organosilicon thin films, the use of sacrificial polymeric<br />
layers to tailor the microstructure of oxide films deposited at room temperature and the microstructural<br />
control of TiO x and MO x /TiOx optical films. Besides, a novel type of organic and nanocomposite<br />
fluorescent films deposited from laser dyes will be discussed. These highly functionalized<br />
thin films are the basis of a novel photonic materials technology (i.e., photonic filters and sensor on<br />
a chip devices).<br />
.<br />
62
JUNE 27 TUESDAY MORNING<br />
JS1-TuM-.INV.4 FUNCTIONAL AND DECORATIVE REFLECTING LAYER<br />
FOR AUTOMOTIVE LIGHTING IN VALEO. J. M. Trigo, R. Acuña, A. Lara and D. Teba,<br />
Valeo Iluminación Martos, Calle Linares 15, 23600 Martos, Jaén. Spain.<br />
The possible developments of metallization process for reflectors are restricted looking for the quality<br />
(maintaining process parameters under control to avoid scraps, creating effective hydrophilic layers<br />
to diffuse more an more fogging materials, homogenizing layers thickness) and productivity (reducing<br />
cycle time, simplifying process steps, decreasing costs and so on).<br />
Following the lean process design rules, the trend is to use short dimension machines as Pylonmet<br />
(Leybold TM) having short cycle times for PECVD, employing classical materials, as Al for reflective<br />
layer and silicone matrix starting from the monomer hexamethyl disiloxane as protective topcoat.<br />
This new concept has the advantages of the sputtering system (material long life, good process<br />
control for product quality consistency, better adhesion with higher layer density) and the advantages<br />
of batch metallization (parts movement and unique chamber).<br />
Many efforts are focused to multiply the decorative possibilities of bezels, some of them without reflective<br />
coatings (mass coloured materials where decorated part is obtained directly by injection of<br />
pigmented thermoplastics); some others employ coloured reflective coatings by changing the metal<br />
itself, creating different chemical reactions with the same metal, giving different colours or with coloured<br />
topcoat.<br />
Paint is an usual choice to give decorative effects on bezels because the metallized pigments give us<br />
some shining appealing surfaces. On some cases, competitive costs can be achieved in front of in<br />
chamber metallization process. Less original effects are achieved masking partially part areas resulting<br />
delimited lines between metallized and non metallized where is visible the natural colour of base<br />
plastic.<br />
The interaction of YAG laser (wavelength on near IR) and reflective coatings, bring us new and<br />
original possibilities for decoration purposes, because laser removes the reflecting layer showing all<br />
kind of patterns by contrast with coloured plastic substrate.<br />
61
JUNE 27 TUESDAY MORNING<br />
JS1-TuM-INV.3 MULTILAYER COATINGS FOR OPTICAL AND ENERGETIC<br />
CONTROL IN GLASSES. F. Villuendas. Departamento de Física Aplicada. Universidad de<br />
Zaragoza. 50009, Zaragoza. Spain<br />
Architectural trends in the last century drove the use of glass façades in construction, since they provide<br />
a lightness aspect to the building, allow the inside-outside communication though the façade and<br />
admit a great variation in the aesthetic aspect. However, the use of glass façades presents several disadvantages,<br />
in particular energetic disadvantages, caused by energy conductive losses with values of<br />
5,7 W/m 2 K in monolithic glass, and by the overheat produced by the excessive solar gain, with values<br />
until 500 W/m 2 in south orientation.<br />
The use of insulating glazing including multilayer sputtered coated glass avoids most of these inconveniences,<br />
giving rise to the development of new products with optimized performances of thermal<br />
isolation and energetic solar transmission. So, sputtering technologies and procedures for large area<br />
glass coatings will be reviewed as the first point in this presentation.<br />
Several coatings have been designed for optical and energetic control in buildings that are often included<br />
in two big groups, solar control coatings that reduce solar transmission of the glazing and<br />
low-emissivity coatings that reflect infrared radiation while they transmit visible light. Optical and<br />
energetic characteristics are determined by absorptive and infrared reflective properties of metallic<br />
layers together with interference conditions in dielectric layers, so that optical and energetic properties<br />
will be dependent on material composition, multilayer structure and thickness of different layers.<br />
Typical multilayer structures for both solar control and low-emissivity coatings will be presented,<br />
showing the optical and energetic characteristics that can be achieved.<br />
The design and development of new multilayer structures with specific energetic and optical properties<br />
is the aim of research activities in our group, that has been carried out in collaboration with the<br />
company Ariño-Duglass. Finally, we present the main features of the design and fabrication processes<br />
followed for the development of several specific purpose coatings, including solar control and<br />
low-emisivitty properties, with improved characteristics of different kinds as those concerning energetic<br />
behaviour, thermal isolation, aesthetic aspect, colour reproduction or chromatic coordinates.<br />
60
JUNE 26 TUESDAY MORNING<br />
JS1-TuM-INV.2 SURFACE TREATMENTS FOR INDUSTRIAL GLASSES J.M. Marco.<br />
Responsable de I+D. Ariño Duglass S.A. La Puebla de Alfinden, Zaragoza. Spain<br />
Glass, as architectural material, has extraordinary characteristics against other transparent materials<br />
in relation to its durability and technical performances. In addition of the intrinsic material characteristics,<br />
glass is subjected to different transformation processes in order to achieve a final product that<br />
fulfils all the requirements demanded in actual architecture. Improvements in mechanical resistance,<br />
safety against breakage, thermal isolation or solar control, are reached by means of several kinds of<br />
treatments. Some of these important performances are only possible through surface processing technologies.<br />
In this presentation, a general overview of the main manufacturing process for industrial glass will be<br />
exposed, underlining the common surface treatments used in this sector. A brief introduction to<br />
products manufactured by pyrolysis and sputtering in order to improve the solar control and thermal<br />
isolation will be presented, exposing real application and performance achieved.<br />
Another important requirement that glass must fulfil is the control over its aesthetic aspect. Application<br />
of paints and enamels by silkprint, roll coating or digital inkjet systems allows to modify the<br />
colour, texture and visual aspect of glass, customizing each architectonical project. Last developments<br />
in float glass decoration and direct application of these products will be presented.<br />
Also, laminated glass technologies give the opportunity to modify the general behaviour of glass, in<br />
this sense it is possible to incorporate a coated or decorated PET that expands the uses of glass. The<br />
possibility to integrate liquid crystal polymers in laminated glass open a way to produce active windows.<br />
Finally, a prospect about new developments expected in the sector will be outlined.<br />
59
JUNE 27 TUESDAY MORNING<br />
JS1-TuM-INV-1 REACTIVE SPUTTERING OF METAL OXIDES AND NI-<br />
TRIDES FOR INDUSTRIAL APPLICATIONS. Victor Bellido-González, Benoit Daniel,<br />
Sarah Powell GENCOA, Physics Road, Liverpool L24 9HP (UK). E-mail: victor@gencoa.com<br />
Magnetron sputtering has become one of the key industrial vacuum coating technologies in regards<br />
to many of today’s applications. In magnetron sputtering, a material called target (e.g. Ti),<br />
suffers ion bombardment by ions of a mainly inert gas (e.g. Argon) and in that bombardment material<br />
is removed and transported onto a desired surface to be coated. The plasma trap around that<br />
target is based on a electric-magnetic cross field (ExB). Some of these processes also involve the<br />
reaction between the element or elements of the target material and a gas. That reaction produced<br />
a coating of very different nature to the target material itself and the process is called reactive<br />
magnetron sputtering. Two groups of these reactive gases are Nitrogen which will give as a result<br />
a nitride of the elements of the target (e.g. TiN) and Oxygen which will give as a result an<br />
oxide of the elements of the target (e.g. TiOx). In some cases the target itself is of a oxide or nitride<br />
nature and generally some sort of degree of reactive sputtering is maintained in order to taylor<br />
specific coating properties (e.g. Ito target sputtering in atmospheres containing O 2 or H 2 ). In<br />
this presentation some of the current issues in the control of such processes will be exposed. Also<br />
practical applications of oxides and nitrides will be explained based on our industrial experience.<br />
These will include multilayer oxides for optical coatings, transparent conductive oxides for<br />
photovoltaic and display technology, oxides for scratch resistance technology, nitrides for decorative<br />
and hard coat applications, solar-thermal absorbers, etc. A short comparison with some<br />
other technologies such as cathodic arc will be exposed as these technologies can be sometimes<br />
found competing on a similar ground of applications.<br />
58
JS1 SESSION<br />
57
JUNE 27 TUESDAY MORNING<br />
TuM-Pl.2 THE ROLE OF ENERGETIC IONS IN THE DEVELOPMENT OF MUL-<br />
TILAYERED X-RAY REFLECTION OPTICS. J. Verhoeven, FOM AMOLF, Kruislaan<br />
407, 1098SJ Amsterdam, The Netherlands<br />
Since the seventies of the past century multilayer systems at nanometre scale have been applied<br />
as spectroscopic elements for wavelengths > 0.1 nm as well as optical reflection systems in the<br />
short wavelength region (
PLENARY<br />
55
TUESDAY MORNING<br />
54
JUNE 26 MONDAY AFTERNOON<br />
WS-18-MoA-OR 5 DYNAMIC EXPANSION SYSTEM AT CEM. C.Matilla;<br />
N.Medina; S.Ruiz. Spanish Centre of Metrology (CEM).<br />
The Spanish Metrology Centre has an orifice-flow primary pressure standard. In this kind of pressure<br />
standard a known flow of gas passes through an orifice of calculated conductance creating a pressure<br />
gradient between both sides of the orifice. The known flow of gas is generated by a precision flowmeter<br />
which can work using the constant volume method or the constant pressure method. Since its<br />
construction the system has suffered several modifications in order to improve its results which will<br />
be described as follows.<br />
The first flowmeter was manually operated. That is the reason why it could basically be used with<br />
the constant volume method. Nowadays it has been completely automatised<br />
and it uses the constant pressure method, which is much more accurate. Data acquisition software<br />
has been designed to monitor all the parts of the system involved. Some parts of the flowmeter have<br />
been correctly isolated by means of aluminium walls to stabilise their temperature.<br />
The first vacuum pump connected to the vacuum chamber was a 300l/s turbomolecular pump. At<br />
present it has been replaced by a 700 l/s turbomolecular pump which allows the system to be closer<br />
to ideal conditions as well as to obtain an appropriate base pressure more easily.<br />
53
JUNE 26 MONDAY AFTERNOON<br />
WS-18-MoA. OR.4 LONG TERM SHIFT IN CAPACITANCE GAUGES: CONTRIBUTION<br />
TO THE TOTAL UNCERTAINTY. J. M. Hidalgo * and J. L. de Segovia** Telstar Industrial S.L.<br />
José Tapiolas 120, O<strong>82</strong>26 Terrassa Spain. ** Instituto de Ciencia de Materiales,CSIC,Cantoblanco,2<strong>82</strong>40Madrid,Spain<br />
e-mail:jldesegovia@icmm.csic.es/j.mhidalgo@telstar.es<br />
One of the contributions to total uncertainty in capacitance gauges is the shift of long-term stability.<br />
This contribution can be only determined by recalibrations usually with a periodicity of one year. In<br />
the present work, we present a study of the “shift” of four capacitance manometers ranging from 1000<br />
mbar to 10 -3 mbar. Recalibration of the reference standard took place at two National Laboratories<br />
with one-year periodicity and for a total time up to six years depending of the gauge. This is an<br />
enough extended period to obtain some conclusions about the long-term stability in this kind of<br />
gauges. Based on their principle of working the higher contribution to the “shift” is expected from the<br />
fatigue of the material of the membrane. The deviation i.e., the difference between the readings of<br />
working standard of the National Laboratory and the calibrating gauge, are also discussed. The several<br />
contributions to the total uncertainty are presented and compared with the uncertainty due to the shift.<br />
As consecutive recalibrations are not performed at the same calibrating points in the primary standard<br />
of the National Laboratory, it is necessary to perform interpolations to obtain the differences of the<br />
readings at the same calibrating points, uncertainty considered in the final expanded uncertainties<br />
52
JUNE 26 MONDAY AFTERNOON<br />
WS-18-MoA.INV.4 CALIBRATION OF PRESSURE SENSORS IN AN INDUSTRIAL<br />
ENVIRONMENT. M. <strong>Wüest</strong>, INFICON Ltd., Alte Landstrasse 6, LI-9496 Balzers, Liechtenstein<br />
National Measurements Institutes calibrate vacuum pressure sensors a few gauges at a time in a laborious<br />
and time consuming fashion resulting in an accurate calibration with small error estimates. A<br />
manufacturer produces a comparatively large number of sensors a day which must be economically<br />
calibrated. Therefore, a manufacturer of vacuum pressure gauges can not spend the same amount of<br />
time at a calibration. Here, we describe a procedure to calibrate vacuum gauges rapidly and cost efficiently.<br />
Maintaining the calibration in an industrial environment is another challenge. Vacuum<br />
gauges are calibrated in the factory in a clean environment with nitrogen. However, during the use of<br />
the gauge, the sensor may encounter an environment which causes coating or etching of sensor elements.<br />
This leads to degradation of the sensor with time and inaccurate pressure readings, but may<br />
be difficult to detect. I will describe examples of contamination and some of the counter measures.<br />
<strong>51</strong>
JUNE 26 MONDAY AFTERNOON<br />
WS-18-MoA-INV.3 CLEANING PROCESSES AND QUALITY CONTROL FOR VAC-<br />
UUM. R J Reid, ASTeC, CCLRC Daresbury Laboratory, Warrington WA4 4AD, UK<br />
Cleaning is an important part of the processing of vacuum components and systems for any level of<br />
vacuum. However, the lower the pressure required, the more stringent the cleaning requirements<br />
must be.<br />
Over recent years, many of the traditional processes used for cleaning have become unacceptable because<br />
of their effect on the environment and, indeed, many have been prohibited by legislation.<br />
In this paper, an outline will be given of the search for the “perfect” cleaning process for UHV and<br />
XHV components which is effective, economical and likely to remain acceptable. We shall discuss<br />
what has become the industry standard use of aqueous detergent based techniques and the use of<br />
some of the newer solvents which have been developed.<br />
Of course, the search for a “perfect” process leads us to pose the question “How do we know when a<br />
system is sufficiently clean?” Some answers to this question will be discussed. This will then lead us<br />
to look at implementation of quality control procedures to ensure that an “as delivered” component<br />
will be satisfactory for purpose.<br />
Examples will be given, including that of a very large XHV vessel currently being manufactured in<br />
Germany.<br />
50
WS-18 SESSION<br />
49
JUNE 26 MONDAY AFTERNOON<br />
RIVA-TF-MoA-OR.16 DUAL DC MAGNETRON CATHODE CO DEPOSITION OF (Al,<br />
Ti) AND [(Al, Ti) N] THIN FILMS WITH CONTROLLED DEPTH COMPOSITION. Y.<br />
Nunes, A. Wemans, H. P. Marques, Q. Ferreira, O. M. N. Todoro and M. J. P. Maneira. Cefitec -<br />
Department of Physics, Faculty of Sciences and Technology, New University of Lisbon, P-2<strong>82</strong>9-<br />
<strong>51</strong>6, Caparica, PORTUGAL.<br />
Recent publications show that [(Ti, Al) N] thin films produced with direct current reactive magnetron<br />
sputtering can significantly improve electrochemical and biocompatibility properties of the base<br />
metal alloy. The purpose of this work is to study the characteristics of titanium-aluminium nitride<br />
[(Ti, Al) N] films produced using a novel coating technique.<br />
Thin (Al, Ti) films with a linear gradient depth composition are obtained from a custom made codeposition<br />
system which employs pure Al and Ti sputter targets. Two direct current magnetron cathodes<br />
with independent plasma sources are simultaneous controlled by custom LabView software<br />
which allows real-time and independent control of the deposition parameters for both cathodes.<br />
Two types of gradient thin films were produced. Starting with 100% Al at bottom and 100% Ti at<br />
surface and starting 100% Ti and ending with 100% Al at surface. Both types of films are of 500nm<br />
thin. Depth profile was acquired using secondary ion mass spectrometry (SIMS). These films of (Ti,<br />
Al) and [(Ti, Al) N], have been grown onto Mg, Glass and Si (100) substrates, the first in argon atmosphere<br />
and the later in nitrogen.<br />
Further analysis will be carried using atomic force microscopy to investigate the surface morphology<br />
and X-ray photoelectron spectroscopy (XPS) in order to detect possible chemical interactions between<br />
the film compounds.<br />
48
JUNE 26 MONDAY AFTERNOON<br />
RIVA-TF-MoA-OR.15 OXIDE THIN FILM COATINGS BY SPRAY PYROLYSIS<br />
ONTO STEEL COILS. R. López Ibáñez. Departamento de Física Aplicada I, Facultad de Ciencias,<br />
Universidad de Málaga, E-29071 Málaga, Spain. F. Martín. Departamento de Igeniería Química,<br />
Facultad de Ciencias, Universidad de Málaga, E-29071 Málaga, Spain. J.R. Ramos-Barrado. Departamento<br />
de Física Aplicada I, Facultad de Ciencias, Universidad de Málaga, E-29071 Málaga,<br />
Spain. D. Leinen. Departamento de Física Aplicada I, Facultad de Ciencias, Universidad de Málaga,<br />
E-29071 Málaga, Spain.<br />
A large scale spray pyrolysis coater has been designed and constructed for industrial pilot trials in<br />
the aim of depositing different functional metallic oxide thin films onto metallic substrates, such as<br />
antireflective layers, self-cleaning films, barrier layers, selective thin films, photocatalytic coatings,<br />
etc. Within the field of solar thermal energy, a zirconia film has been produced onto an aluminized<br />
steel coil of 0.4 m width which has been previously coated with a selective layer elsewhere. The zirconia<br />
film as a top-coat has the function of anticorrosion and protection against ambient impact in<br />
outdoor conditions.<br />
Technical details: Zirconium acetyl-acetonate in a 0.02 molar aqueous solution was used as precursor<br />
for spraying onto the 200º C heated substrate, growing in these conditions aproximately a 10 nm<br />
thick zirconia thin film. After several coating repetitions an 80 nm ZrO 2 thin film was produced.<br />
Characterization: UV-Vis-NIR-MIR hemispherical reflectance spectroscopy showed that the zirconia<br />
coating is highly transparent and acts as an antireflection layer, increasing the solar absorptance in<br />
about 10 %, but not degrading the thermal emittance at 373K, thus improving optical properties for a<br />
solar thermal device. SEM revealed a dense film which covers well the substrate sealing existing<br />
pores. No cracks could be seen on the surface of the coating even after repeating the coating process<br />
for several times, rolling up and unrolling the steel belt from its cylindrical storage. XPS depth profile<br />
analysis showed that the material was well pyrolysed to zirconium oxide. Only 3% of carbon remaining<br />
from the precursor was found inside the film, stabilized in a ZrC phase homogeneously diluted<br />
across the zirconia film thickness. No crystalline structure was detected by XRD. Linear polarization<br />
measurements were carried out in 0.5 molar sodium chloride aqueous electrolyte solutions.<br />
A reduction in the registered current densities showed a decrease in corrosion attack by approximately<br />
one order of magnitude when comparing to the corrosion behaviour of the substrate itself.<br />
Conclusions: Compact, homogeneous and well synthesized zirconia thin films have been deposited<br />
onto a continuously moving steel belt with an industrial scale spray pyrolysis pilot station. The zirconia<br />
film improves corrosion resistance and the optical properties of the layer stack, zirconia topcoat,<br />
selective layer, aluminized steel substrate, with regard to solar thermal applications.<br />
Acknowledgements: Funds from the EU (project SOLABS: ENK6-CT2002-00679) are gratefully<br />
acknowledged.<br />
EU Project SOLABS: Development of unglazed solar absorbers (resorting to coloured selective coatings on steel material)<br />
for building facades, and integration into heating systems. www.solabs.net<br />
47
JUNE 26 MONDAY AFTERNOON<br />
RIVA-TF-MoA-OR.14 STUDY OF THE EFFECT OF SILICON EXCESS AND ARTIFI-<br />
CIAL AGEING ON THE MICROSTRUCTURAL STABILITY OF Al-Mg-Si ALLOYS. Y.<br />
Aouabdia*, Boubertakh ABDEL HAMID*, Hamamda SMAÎL*. * Laboratoire des Propriétés Thermodynamiques<br />
et des Traitements de Surface des Matériaux. Faculté des Sciences, Université Mentouri-Constantine<br />
Route Ain El-Bey, 25000 Constantine, Algérie<br />
aouabdiayoucef@yahoo.fr<br />
The use of Al based alloys for automotive body materials has been driven by a number of issues, in<br />
particular weight saving. We are interested in in Al–Mg–Si alloys with excess Si. For this work, we<br />
study the effect of excess Si on the precipitation of the β’’ phase. Samples from an Al–Mg 2 Si–0.5%S<br />
were studied by differential scanning calorimetry (DSC), optical microscopy, Vickers hardness test<br />
ing, and MEB. Data on reaction kinetics, grain size, and micro-hardness are analyzed with reference<br />
to a stoichiometric alloy. This study revealed that excess Si increases the activation energy for the re<br />
action, and globally improves the mechanical properties of the alloy. The precipitation sequence in the<br />
Al-Mg-Si alloys with excess silicon is generally accepted to be:<br />
clusters of solute atoms GP zone IGP zone II/ β” β’ β (Mg 2 Si)+Si<br />
Key words: Al–Mg– Si alloys, excess Si, precipitation, activation energy, β'<br />
46
JUNE 26 MONDAY AFTERNOON<br />
RIVA-TF-MoA-OR.13 BREAKDOWN VOLTAGE IN MAGNETRON DC GLOW DIS-<br />
CHARGES. THE INFLUENCE OF THE MAGNETIC FIELD. Y. Nunes, A. Wemans, P. R.<br />
Gordo and M. J. P. Maneira. Cefitec - Department of Physics, Faculty of Sciences and Technology,<br />
New University of Lisbon, P-2<strong>82</strong>9-<strong>51</strong>6, Caparica, PORTUGAL.<br />
In abnormal glow discharges with magnetic field, the electrons are confined in a trap near the cathode<br />
allowing work at lower pressures and voltages. For thin film applications this can influence positively<br />
the quality of the sputtered film and decreases the processing time.<br />
d<br />
Fig1. Cathode mounted in the system<br />
and the copper discharge on argon.<br />
Fig2. Magnetic circuit position inside<br />
the cathode body<br />
In this work breakdown voltages of the abnormal glow discharges of argon on copper with magnetron<br />
assistance, are measured for different magnetic configurations.<br />
To achieve this, a cathode, shown in Fig.1, was constructed with a magnetic circuit, based on permanent<br />
NdFeB, which can be systematically moved allowing fine control of magnetic field distribution,<br />
see Fig.2. This way the influence of the magnetic field in the plasma parameters and in particular the<br />
influences in the breakdown voltage are studied.<br />
The breakdown voltages are measured and presented as a function of pressure for different distances<br />
of the magnetic circuit to the target. The study takes in account a range of pressures from 0.2 to 32<br />
Pa and a range of the parallel component of the magnetic induction, from 0.3 T to 1.7 T at the target<br />
surface.<br />
The expression,<br />
V ( P)<br />
= C ⋅e<br />
B<br />
1<br />
P<br />
−<br />
C2<br />
+ C + C ⋅ P<br />
3<br />
4<br />
fits the data of breakdown voltage dependence on the working pressure, with high correlation coefficient<br />
and the constants depend on magnetic distribution<br />
At each magnetic configuration the first exponential term accounts for low pressure range and the<br />
linear term accounts for the higher pressure range. Minima similar to what happens in Paschen’s<br />
Law, are observed which shifts to lower pressure with increase of the magnetic field. This behavior<br />
is systematic and regular.<br />
45
JUNE 26 MONDAY AFTERNOON<br />
RIVA-TF-MoA-OR.12 STRUCTURAL, ELECTICAL AND OPTICal PROPERTIES OF<br />
INDIUM-TIN-OXIDE THIN FILMS preparED by pULSED LASER DEPOSITION. A.<br />
Khodorov, M. Piechowiak* and M.J.M.. Gomes. Physics Center, University of Minho, 4710-057<br />
Braga, Portugal. *Department of Material Science, University of Silesia, 41-200 Cosnowiec, Poland<br />
Indium-tin-oxide (ito) films show an interesting and technologically important combination of properties:<br />
excellent substrate adherence, hardness, chemical inertness, good electrical conductivity and<br />
high transparency in the visible range of electromagnetic spectrum. for using ito films as transparent<br />
electrodes to grow multilayer structures the crystalline quality and preferred orientation of domains<br />
in the films are very important.<br />
In this work we prepared ito thin films by pulsed laser deposition at different temperatures (from 24<br />
up to 600 o c) with several oxygen pressures on glass substrate. the texture selection and cell parameters<br />
were studied with help of x-ray diffraction. the sheet resistance was determined by a four-pointprobe<br />
method at room temperature. the optical properties were examined in the wave-length range<br />
200 - 3200 nm. the dielectric function of ito film was obtained by fitting the measured transmission<br />
and reflection spectra to a dispersion relation, which combines the drude model and lorentz oscillator.<br />
the well crystallized, highly textured and highly transparent films were grown at high temperatures.<br />
variation of substrate temperature as well as oxygen pressure during deposition results in different<br />
structural, electrical and optical properties. the correlation between deposition conditions and<br />
physical properties of ito films was observed and analysed.<br />
This work was supported by fct (grant sfrh/bpd/11675/2002)<br />
44
JUNE 26 MONDAY AFTERNOON<br />
RIVA-TF-MoA-OR.11 ADSORPTION PROPERTIES, MICROSTRUCTURE AND OP-<br />
TICAL BEHAVIOUR OF TIO 2 THIN FILMS PREPARED BY PECVD. A.Borrás, A. Barranco,<br />
J. Cotrino, A.R. González-Elipe. Instituto de Ciencia de Materiales de Sevilla (CSIC-Univ.<br />
Sevilla). Avda. Américo Vespucio s/n. 41092 Sevilla (Spain)<br />
It is a common place that the type of microstructure of thin films is critical for an effective control of<br />
their optical properties. Usually, the microstructure is monitored by direct observation by SEM and<br />
related microscopies. Recently, the use of spectroscopic ellipsometry under controlled ambient conditions<br />
to measure adsorption isotherms has become an interesting technique to asses the type of porosity<br />
in the films. In the present paper we discuss the possibilities of the adsorption isotherm technique<br />
measured by means of a quartz crystal monitor (QCM) to asses the porosity of TiO 2 thin films<br />
prepared by PECVD under different conditions. The microstructure and optical properties of the<br />
films have been also characterized by SEM and optical methods. A large variety of TiO 2 thin films<br />
with different microstructures and optical constants (n ranging from 1.8 to 2.2) have been obtained.<br />
SEM gives information about the type of microstructure developed in the films (columnar, globular,<br />
homogeneous, etc.). In addition, the water isotherms measured with the QCM provides important information<br />
about the type of pores present in the films (i.e., micro, meso or macro pores) and the pore<br />
size distribution. The analysis of the reversibility of the adsorption processes, as well as the dependence<br />
of the adsorption characteristics as a function of the thin film thickness, have furnished important<br />
clues to explain the optical properties of the films and their dependence on thickness. Small<br />
variations of the optical constant of thin films exposed to the atmosphere can be also explained by<br />
realising the irreversibility of some of the adsorption processes under ambient conditions.<br />
The use of adsorption isotherms of vapours to characterize the porous structure of thin films can be<br />
considered as an universal tool for the porous characterization of these materials providing complementary<br />
information on the microstructure of the films<br />
43
JUNE 26 MONDAY AFTERNOON<br />
RIVA-TF-MoA-OR.10 THE INFLUENCE OF MAGNETIC CONFINEMENT IN DI-<br />
RECT ABNORMAL GLOW DISCHARGES. Y. Nunes, A. Wemans, P. R. Gordo and M. J. P.<br />
Maneira. Cefitec - Department of Physics, Faculty of Sciences and Technology, New University of<br />
Lisbon, P-2<strong>82</strong>9-<strong>51</strong>6, Caparica, PORTUGAL.<br />
In this work an experimental study of the magnetic field influence on planar magnetron abnormal<br />
glow discharges of argon on copper targets is presented. A magnetron cathode that allows the control<br />
of the magnetic configuration was developed, and its magnetic circuit characterized.<br />
To quantify the magnetic field influence in the discharge, a confinement power parameter C B , was<br />
defined. This parameter, takes into account simultaneously the useful volume of the field, V C , and<br />
the average of the parallel component of the magnetic induction to which the plasma is subjected.<br />
For a planar magnetron cathode with cylindrical symmetric magnetic field, where r and z are the radial<br />
and height coordinates, and B || the parallel component of the magnetic field in this coordinate.<br />
The confinement power parameter is:<br />
C<br />
∫∫<br />
B<br />
= 2 π<br />
||<br />
)<br />
V C<br />
B ( r,<br />
z rdrdz<br />
Current-voltage-pressure characteristics were measured and the influence of the confinement power<br />
is mapped through current-voltage curves at constant confinement power values, displayed at several<br />
pressures. It was showed that at higher confinement power values the behaviour of the I-V characteristics<br />
is in general well described by the Thornton empirical law, I=kV n .<br />
Systematic study of k and n Thornton parameters with confinement power will be presented. The results<br />
show that above certain value of C B, the Thornton parameter, n, that is considered to characterise<br />
the entrapment efficiency of the electrons, converges to a constant for pressures from 1 to 8 Pa, as<br />
can be seen in Fig1.<br />
Fig.1 – Thornton parameter<br />
n as function of confinement<br />
power C B.<br />
The data shows also that there is dependence between n and k, Thornton parameters.<br />
42
JUNE 26 MONDAY AFTERNOON<br />
RIVA-TF-MoA-OR.9 INFLUENCE OF PRESSURE ON THE STRUCTURAL ME-<br />
CHANICAL AND DECORATIVE PROPERTIES OF TiN THIN FILMS DEPOSITED BY<br />
CATHODIC ARC EVAPORATION. A. Lousa, J. Esteve. Departamento de Física Aplicada y<br />
Óptica, Universidad de Barcelona, Avda. Diagonal 647, E-08028 Barcelona, Catalunya, Spain. J.P.<br />
Mejia, A. Devia. Laboratorio de Física del Plasma, Universidad Nacional de Colombia Sede Manizales,<br />
Campus La Nubia, Manizales, Colombia.<br />
Titanium nitride TiN is one of the hard materials most widely studied and commonly used as decorative<br />
coatings, wear-resistant coatings, diffusion barriers and electrodes in industrial applications. TiN<br />
coatings are deposited by different PVD and CVD deposition techniques. The typical gold color of<br />
TiN makes it an attractive candidate for decorative applications. TiN can be obtained in a relatively<br />
wide range of compositions around stoichiometry. Changing the stoichiometry around the 1:1 composition<br />
broadens the spectrum of colors and can modify the mechanical properties compared with<br />
those of stoichiometric TiN.<br />
Cathodic Arc Evaporation (CAE) is a especially attractive PVD deposition technique both for its<br />
unique abilities (highly ionized vapor which allows ion energy control through substrate bias voltage,<br />
high deposition rates, excellent adhesion), and for been widely use in industrial applications. It<br />
is well known that composition, structure and properties of the deposited films depend on the process<br />
parameters such us growth temperature, substrate bias voltage, gas pressure in the vacuum chamber.<br />
The purpose of this work is to study the feasibility of depositing TiN coatings of different gold tones<br />
with good mechanical properties by using a metallic Ti cathode and varying the nitrogen partial pressure<br />
in a CAE reactive process. This pressure was varied between 5x10 -4 and 3x10 -2 mbar. The other<br />
technological parameters were kept fixed for all the samples at the following values: cathodic current,<br />
60 A, substrate temperature 400 ºC, substrate bias voltage, -300 V. The coatings were deposited<br />
on polished steel substrates.<br />
The resulting film thickness varied between 1-2 microns, with high deposition rates which ranged<br />
from 8 μm/h for the samples deposited at low pressure, to 4 μm/h for the samples deposited at high<br />
pressure. The composition of the coatings studied by XPS indicates an increasing nitrogen content as<br />
the nitrogen partial pressure is increased. SIMS analysis shows that this composition is uniform<br />
throughout the coatings thickness. The crystalline structure was studied by XRD which shows typical<br />
diffraction patterns corresponding to polycrystalline TiN. The evolution of the crystalline structure<br />
with pressure is discussed in terms of grain size and preferred orientation. The color characteristics<br />
of the samples were analyzed by spectral reflectometry in the visible range. The reflectivity<br />
spectra show a gold-like shape with significant shifts that correlates to the nitrogen content in the<br />
samples. The mechanical properties of the coatings were characterized by dynamical nanoindentation<br />
(NanoTest 550, Micro Materials Ltd.) with a Berkovich diamond tip. The hardness and Young’s<br />
modulus values were obtained by the Oliver and Pharr analysis method. The Young modulus values<br />
resulted close to the bulk TiN value (310 GPa). The hardness of the coatings increases with nitrogen<br />
pressure until reaching a maximum of 24.5 GPa at 1.3x10 -2 mbar, in the intermediate zone of the<br />
studied range, and decreasing for higher pressures.<br />
In summary, we have shown that the control of the nitrogen pressure is useful to obtain TiN coatings<br />
with a wide palette of gold colors and good mechanical properties.<br />
41
RIVA-TF SESSION<br />
40
JUNE 26 MONDAY AFTERNOON<br />
ETCHC-MoA-INV.3 THERMAL BEHAVIOUR OF W-SI-N HARD COATINGS IN<br />
PROTECTIVE AND OXIDATION ENVIROMENTS. A. Cavaleiro, ICEMS -Faculdade de<br />
Ciências e Tecnologia da Universidade de Coimbra, Dep. Eng. Mecânica, Rua Luís Reis Santos,<br />
3030-788 Coimbra, Portugal<br />
Extensive discussion has been raised concerning the structural arrangement in TM-Si-N<br />
(TM=transition metal) nanocomposite coatings, particularly on the way how Si is present in the coatings.<br />
Furthermore, abundant results on the hardness and Young´s modulus of these films is available<br />
in the literature, particularly for TM = Ti and Zr. As a function of the phase arrangement, different<br />
interpretations and discussions on the hardening mechanisms involved in the mechanical behaviour<br />
of the coatings, have been raised such as, grain size, residual stress, lattice distortion. Many authors<br />
defend that the hardness of TM-Si-N films depends only on the purity, dimensions and distribution<br />
of the Si-N phase in relation to the TM nitride grains.<br />
W-Si-N is a particular case in the world of TM-Si-N systems (TM=Ti, Zr), due to the different<br />
chemical affinity among the elements. In fact, the affinity of N for W is much lower that the one of<br />
Si, inversely to the case of e.g. Ti-Si-N where similar affinities of Ti and Si for N are observed. Such<br />
a fact determines the arrangement of the phases during the deposition and has a huge influence on<br />
the structural stability of the coatings when annealed at increasing temperatures. The main consequences<br />
are: (1) much higher N 2 partial pressures are needed for depositing films with W-nitride<br />
phases and (2) after thermal annealing no W-nitride is detected in the films. However, the coatings of<br />
this system can also show hardness values as high as 45GPa even if the main phase (W-based) his<br />
typically a metallic bonding type based material..<br />
In this talk, the current knowledge on the thermal annealing of W-Si-N sputtered films in both protective<br />
and oxidant atmospheres is reviewed. Firstly, sputter deposited single W films are presented<br />
as a particular case of metallic element films and their thermal annealing analyzed. The transition for<br />
the W-Si-N films permitted to conclude that the addition of Si promotes a loss of the crystallinity degree<br />
until amorphous structures are reached. Generally, amorphous coatings (20-30GPa) are softer<br />
than crystalline ones (25-45GPa). Afterwards, the thermal stability of W-Si-N coatings is considered<br />
either in protective or oxidant atmospheres. Special attention is paid for amorphous films. In protective<br />
atmosphere, it is shown that after crystallization the hardness can be higher than that of asdeposited<br />
crystalline films with similar structure. The hardest films have a single W-metallic phase<br />
mixed with amorphous Si-N phase.<br />
The Si content is determinant in the oxidation resistance: the higher the Si content the lower the oxidation<br />
rate is. As an example, the weight gain reached by a coating without Si at 650ºC is similar to<br />
the one shown by a high Si content film (>30at.%) at 1000ºC. The oxidation resistance is attributed<br />
to either the formation of a continuous protective Si-rich layer or to the synergetic effect of a very<br />
low oxide grain phase and a very high compactness of the oxide scale.<br />
39
JUNE 26 MONDAY AFTERNOON<br />
ETCHC-MoA-OR.10 MODIFICATIONS OF TRIBOLOGICAL BEHAVIOUR OF<br />
STAINLESS STEELS BY DUPLEX TREATMENTS. R. J. Rodriguez, J.A. Garcia, R.<br />
martinez, G. G. Fuentes. AIN. Centro de Ingeniería Avanzada de Superficies. 31191 Cordovilla,<br />
Pamplona, Spain<br />
Ordinary PVD coatings exhibites adequate properties from the point of view of hardness, friction or<br />
wear coefficient to provide a solution good enough for many of the problems. However, they are 2 –<br />
5 μm thick, a limit that can not be surpassed due to internal stresses that lead to crack formation and<br />
delamination. In addition, soft substrates like stainless steels are not adequate to be coated by a hard<br />
material (hardness beyond 15 GPa), because the plastic flow of the substrate induces the fracture of<br />
the hard coating even at medium contact pressures.<br />
DUPLEX treatments (ion nitriding + PVD coatings) have been proposed as a solution for the<br />
treatment of metal alloys like, stainless steels, titanium alloys or, even, aluminium alloys, as well as<br />
tool steels. Most of PVD industrial systems could be adapted to provide an ion nitriding treatment<br />
prior to the PVD deposition process. Both treatments can be applied in the same chamber, without<br />
breaking the high vacuum conditions to prevent contamination.<br />
This papers reports the results obtained on on AISI 304 and 316 stainless steels by a DUPLEX<br />
treatments: Ion nitriding + PVD coating. An adapted arc-evaporation PVD coater has been employed<br />
to produce nitrided layers of 10 – 20 μm with different process parameters, by employing an original<br />
nitriding process based on the AEGD configuration. The same equipment has been used to<br />
subsequently deposit the PVD coatings.<br />
GD-OES analysis and FE-SEM inspection have allowed to characterise the main features of<br />
DUPLEX treatments in comparison with ordinary coatings. Changes in roughness, micro-hardness,<br />
adhesion, friction and wear coeficcients have been measured. As an overall conclusion, both<br />
DUPLEX treatments have shown improved properties and better behaviour.<br />
KEYWORDS PVD, nitriding, duplex treatment, tribology.<br />
38
JUNE 26 MONDAY AFTERNOON<br />
ETCHC-MoA-OR.9 CHANGES DETECTED IN ECR-CVD AMORPHOUSAND NI-<br />
TROGENATED AMORPHOUS CARBON FILMS BY INCREASING PLASMA ION ION<br />
ENERGY. J.G. Buijnsters, M. Camero, L. Vázquez, C. Gómez-Aleixandre, J.M. Albella, Instituto<br />
Ciencia de Materiales, CSIC, Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain<br />
Hydrogenated amorphous carbon (a-C:H) and nitrogenated amorphous carbon (a-CN:H) thin films<br />
may present interesting properties like high smoothness, low friction coefficient, high hardness and<br />
high wear resistance which make them excellent candidates for different applications. a-C:H and a-<br />
CN:H films have been grown from methane/argon and methane/nitrogen/argon gas mixtures respectively<br />
by Electron Cyclotron Resonance Chemical Vapour Deposition (ECR-CVD). During the<br />
deposition process, a negative DC bias voltage was applied to the substrate in order to obtain high<br />
energy ions arriving at the growing surface. The effect of the ion energy on the structural, morphological<br />
and mechanical properties of the films has been explored by multiple analysis techniques.<br />
The obtained results clearly show a sharp change in the properties of the a-C:H and a-CN:H layers<br />
from a threshold ion energy in the order of 100 eV for the production of hard, low-friction coatings.<br />
For no bias application or bias voltages more positive than –100 V, cauliflower shaped and relatively<br />
soft polymeric (nitrogenated) carbon films are formed. The change in the properties of the films deposited<br />
in the two distinct deposition regimes has been associated with the new nanostructure of the<br />
films detected by surface analysis techniques.<br />
37
JUNE 26 MONDAY AFTERNOON<br />
ETCHC--MoA-INV.2 NANOSTRUCTURED PVD COATINGS ON THE VERGE OF<br />
INDUSTRIAL APPLICATIONS. Rafael J. Rodríguez, José-Antonio García, Gonzálo García and<br />
Rosario Martínez. AIN. Centro de Ingeniería Avanzada de Superficies. 31191 Cordovilla – Pamplona,<br />
SPAIN.<br />
The search for new high performance coatings has experienced a relevant progress due to the recent<br />
attention paid to the properties of nanostructured materials. In the last ten years a huge amount of results<br />
have been published describing how nanostructured PVD coatings may exhibit excellent combinations<br />
of different properties, including super- or ultra- hardness, extreme wear resistance, higher<br />
toughness and corrosion resistance.<br />
Most of these results have been achieved at laboratory scale. It seems that there is a real difficulty to<br />
scale up these promising findings to exploitable industrial applications. By the way, this has been not<br />
any obstacle for employing the mark “nano-“ in many commercial names of new coating introduced<br />
in the market in the last five years.<br />
This paper intends to make a review of most interesting strategies employed for the research groups:<br />
nano-multilayers and nanocomposites approaches. A critical revision of the claimed new properties<br />
is made, paying special attention to their possibilities of industrialization. Related problems like<br />
techniques and standards to measure the coatings characteristics are also reviewed.<br />
Keywords: PVD, multilayers, nanocomposites, industrial applications.<br />
36
ETCHC SESSION<br />
35
MONDAY AFTERNOON<br />
34
JUNE 26 MONDAY MORNING<br />
WS-18-MoM-OR.3 NEUTRAL PRESSURE MEASUREMENTS IN TJ-II PLASMAS.<br />
F.L Tabarés, D. Tafalla and J.A. Ferreira. Laboratorio Nacional de Fusión por Confinamiento<br />
Magnético, CIEMAT, Avda Complutense 22, Madrid<br />
The density of neutral species in the periphery of a hot plasma, such as in those generated for Fusion<br />
research, represents a net particle source, ideally in equilibrium with the recycling flux of particles<br />
escaping the plasmas due to limited magnetic confinement. Its measurement in Fusion plasmas is of<br />
crucial interest in particular when divertors are used for the control of the particle and power outflux,<br />
and several concepts have been put forth for its recording (1). In limiter devices, however, its<br />
measurement has always been rather problematic. This is mostly due to the difficulty in defining the<br />
concept of pressure itself under such anomalous conditions, i.e., in the region between the hot plasma<br />
and the walls, where strongly non-thermal equilibrium conditions prevail. Even so, the recording of<br />
the manometer readings during the plasma production can provide very useful information about the<br />
particle confinement and recycling. In the TJ-II stellarator (2), a set of manometers, including<br />
Bayard-Alpert gauges and baratrons, is routinely used for the control of the particle fluxes injected<br />
into the plasma. Recently, the direct reading of the pressure evolution during the plasma shot at regions<br />
away from the gas injection ports has also become available. Neutral pressures values in the<br />
order of 10 -5 -10 -4 mbar have been recorded, depending on plasma heating and wall recycling conditions.<br />
In this work, the technique of measurement and the interpretation of the readings will be described.<br />
The implications for the density control of the plasma and the possible improvements for future<br />
analysis of the particle out-flux will be also discussed.<br />
1. H.F. Dylla. J. Vac. Sci. Tech. 20 (19<strong>82</strong>) 119<br />
2. F.L Tabarés, A. García, J. Botija, 45 Vacuum (1994) 1059<br />
33
JUNE 26 MONDAY MORNING<br />
WS-18-MoM-INV.2<br />
Metrology<br />
VACUUM STANDARDS AT CEM. C. Matilla. Spanish Centre of<br />
In the next future CEM will have three different vacuum standards to cover all the vacuum range.<br />
These standards are a dynamic expansion system, a static expansion system and a forced balance piston<br />
gauge. The dynamic expansion system is based on the known orifice flow technique in which a<br />
flowmeter is used to generate a known flow rate of gas in a vacuum chamber partitioned by an orifice<br />
of calculated conductance. It has been working for some years but it has suffered several modifications<br />
to make it more accurate. The forced piston balance is a recent acquisition. It is a pressure<br />
standard designed to cover the range from less than 1 Pa to 15 kPa gauge and absolute pressures. The<br />
instrument operates on the piston gauge principle in which the pressure on the piston is measured by<br />
a forced balanced load cell. We were encouraged to acquire it by the good results obtained by other<br />
metrology institutes. At the moment we are testing its performance and we are satisfied with its results.<br />
The static expansion system is based on Boyle´s law with corrections. It is a project in collaboration<br />
with EUITT (UPM), which has been founded by the R&D National Plan. This project will be<br />
finished in 2008.<br />
32
JUNE 26 MONDAY MORNING<br />
WS-18-MoM-OR.2 NUMERICAL MODELING OF THE ION BEAM TRANSMIS-<br />
SION EFFICIENCY FOR DESIGN OF THE VACUUM SYSTEM OF THE DC-60 CYCLO-<br />
TRON. A.V. Tikhomirov, G.G. Gulbekian, B.N. Gikal. Flerov Laboratory of Nuclear Reactions,<br />
Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Moscow region, Russia.<br />
The results of a numerical simulation of the transmission efficiency of ion beams in conditions of ion<br />
recharge on the residual gas in the channel of the axial injection, in the DC-60 cyclotron vacuum<br />
chamber, as well as in transport lines of accelerated beams are presented. The computer modeling<br />
programs GENAP and VACLOS have been used. They have been developed and tested on the basis<br />
of experiments on four cyclotrons of heavy ions of the Flerov Laboratory of Nuclear Reactions. They<br />
also have collected an experience of vacuum systems’ design of a number of projects for both design<br />
of new cyclotrons and their upgrade. The simulation programs estimate ion beam losses on the basis<br />
of pressure distribution modeling in vacuum chambers of any arbitrary geometry and also on cross<br />
sections calculation for a recharge of ions in exchange reactions by electrons with molecules of residual<br />
gas in a wide range of energies and masses of ions being accelerated. The outcomes of modeling<br />
have provided the determination of main parameters and technical requirements for the vacuum<br />
system of the DC-60 cyclotron designed for the heavy ion and proton accelerator complex of the<br />
University in Astana of the Republic of Kazakhstan<br />
31
JUNE 26 MONDAY MORNING<br />
WS-18-MoM-OR.1 MASS SPECTOMETRIC ANALYSIS OF COMPLEX GAS<br />
MIXTURES BY USING A CRYOGENIC TRAP: APPLICATION TO H2:CH4:N2 PLAS-<br />
MAS. Jose A. Ferreira and Francisco L. Tabarés. Laboratorio Nacional de Fusión por Confinamiento<br />
Magnético, CIEMAT, Avda Complutense 22, Madrid<br />
The interpretation of mass spectra from gas mixtures showing strong overlapping of the cracking<br />
contributions from their constituents has been always challenging, and it is particularly problematic<br />
in carbon film deposition plasmas, with strong contribution from several kinds of hydrocarbons. In<br />
the present work we describe the use of a cryogenic trap, suitable for thermal desorption studies<br />
above liquid nitrogen temperatures, for the discrimination of species with overlapping cracking patterns.<br />
The cryogenic trap is a simplified model of that described by C. Leitao et al. [1]. A DC glow<br />
discharge with a total pressure of 10 mtorr was produced in a mixture of H 2 :CH 4 :N 2 with 80, 10 and<br />
10 percent respectively. These types of plasmas are of particular interest in fusion research in relation<br />
to a new technique being developed for the mitigation of tritium trapping by codeposition in the<br />
next step fusion reactor [2]. The complex reactions present in the plasma lead to the formation of<br />
numerous stable species that are difficult to identify by mass spectrometry alone. Thus, for example,<br />
the presence of N 2 and CH 4 prevents the use of 28, 29, 16, 15 mass peaks in the deconvolution of the<br />
spectra. Some volatile compounds like acetylene, hydrogen cyanide, ethylene etc. [2] are produced in<br />
this kind of glow, conveying important information about the reactive processes taking place in the<br />
plasma. However, their cracking peaks are strongly masked by the main plasma species. Many of<br />
these compounds can be readily condensed at the liquid nitrogen temperature, 78 K. Once exposed to<br />
the plasma products, the cryogenic sample can be ramp-heated to desorb the volatile species, therefore<br />
obtaining different mass peaks that evolve with the temperature ramp depending on the dew<br />
point of the different species. The obtained data are then compared to previous studies in this type of<br />
mixtures.<br />
[1] Carlos M.M. Leitao et al. Vacuum, Vol 52 (1999) 23-26<br />
[2] F. L. Tabarés, V. Rohde et al. Plasma Phys. Control. Fusion, Vol 46 (2004) B381-B395<br />
30
JUNE 26 MONDAY MORNING<br />
WS-18-MoM.INV.1 STANDARS AND CALIBRATIONS IN VACUUM TECHNOL-<br />
OGY. Karl Jousten, Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin, Germany.<br />
The measurement and control of vacuum is an important condition for many industrial processes,<br />
e.g. for the coating of glasses, of DVDs und CDs, as well as the production of hard disks, memory<br />
chips and processors for computers. In the future it may be even possible that extreme ultraviolet<br />
light (EUV) is used for lithography in the semiconductor industry which makes vacuum necessary<br />
for the transport of the EUV light. The reflective mirrors will need very good vacuum conditions in<br />
order to keep their reflectivity timely stable and to make the whole lithography process a commercial<br />
success.<br />
For most applications vacuum has turned into a full commodity in the past 20 years, where the buyer<br />
has not to care about its functioning. In this scheme, traceable vacuum gauge calibrations and the establishing<br />
of standards have become to play an important role.<br />
Traceable vacuum gauge calibration means that the reading of a calibrated gauge can be traced to a<br />
primary standard for vacuum pressures that ensures highest accuracy and the traceability to the<br />
physical units of the SI. Primary standards are operated by the national metrological institutes.<br />
In 1999 most of the states of the meter convention signed a mutual recognition arrangement, by<br />
which calibration certificates of national metrological institutes are accepted in all these states when<br />
some conditions are fulfilled, among them a quality management system as described in the ISO<br />
standard <strong>17</strong>025.<br />
For the further dissemination of the vacuum pressure scale as well as the characterisation of vacuum<br />
pump performance, ISO specifications and standards have been developed or are presently under development.<br />
This talk will give a complete overview of the vacuum primary standards, the international system of<br />
checking their validity, the scheme of the gauge calibrations down to the end user as well as making<br />
notes on the accuracy and reliability of vacuum gauges. The international standardisation work for<br />
vacuum technology will be described, also.<br />
29
WS-18 SESSION<br />
28
JUNE 26 MONDAY MORNING<br />
RIVA-TF-MoM-OR.8 STUDY OF THE DC-SPUTTERED Mo ON POLYMER SUB-<br />
STRATE FOR FLEXIBLE CIGS SOLAR CELLS M. Andrés and M.T. Gutiérrez. Dep. of Energy,<br />
CIEMAT. Avda. Complutense, 22. 28040 Madrid SPAIN.<br />
For the last few years interest in flexible thin film solar cells has been growing for space power applications,<br />
building integration and portable electronic. Thin film Copper Indium Gallium Selenide<br />
(CIGS) has been established as a leading contender to these applications. In a recent publication different<br />
approaches to flexible CIGS thin-film solar cells has been reviewed [1]. There are numerous<br />
challenges in developing the technology for manufacturing flexible CIGS, the substitution of the<br />
well-established soda-lime-glass substrate by a flexible alternative with drawbacks and without the<br />
generation of new obstacles is not a minor problem. The substrate requirements for flexible CIGS solar<br />
cells are related with a high thermal stability, a sufficient film adhesion and an adequate surface<br />
morphology.<br />
Molybdenum (Mo) has been used almost exclusively as a back contact material for CIGS-based<br />
photovoltaics. Key requirements of the Mo-coated polyimide films for photovoltaic applications are<br />
a high electrical conductivity, ohmic contact to CIGS, and high temperature stability in the presence<br />
of selenium during CIGS absorber deposition.<br />
The aim of the work has been to prepare Mo-coated glass and polyimide and to evaluate their performance<br />
as flexible back contact for CIGS solar cells. The intrinsic stress, orientation, adhesion,<br />
microstructure, reflectance and electrical resistance of dc-sputtered Mo films on glass and polymer<br />
substrates has been studied as a function of deposition parameters.<br />
Following Thorton and Hoffman [2-4], who comprehensively studies stress in sputtered metallic<br />
coatings, we have investigated the effect of Ar gas pressure on the internal film stress in magnetron<br />
sputtered Mo with particular emphasis on the problems that are encountered when relatively high<br />
melting point Mo coatings, with low thermal expansion coefficient , are deposited on polyimide substrates<br />
having relatively high thermal expansion coefficient. Substrate expansion due to heating during<br />
deposition places a tensile stress on the coating which is sufficiently large to cause cracking. This<br />
difficulty is overcome most effectively by depositing the coating under conditions that build a compressive<br />
intrinsic stress into the coating.<br />
[1] F. Kessler , D. Hermann and M. Powalla, Thin Solid Films 480-481 (2005) 491<br />
[2] J.W. Hoffman, J. Vac. Sci. Technol. A 12(4) (1994), 953<br />
[3] J.A. Thorton and D. W. Hoffman, Thin Solid Films, <strong>17</strong>1(1989) 5<br />
[4] D. W. Hoffman and J.A. Thorton, J. Vac.Sci. Technol. 20 (19<strong>82</strong>) 355<br />
27
JUNE 26 MONDAY MORNING<br />
RIVA-TF-MoM-OR.7 INFLUENCE OF THE YTTRIUM CONTENT ON THE ME-<br />
CHANICAL PROPERTIES OF Y 2 O 3 -ZrO 2 THIN FILMS PREPARED BY EB – PVD. I. M.<br />
Ochando. Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones<br />
Científicas. Cantoblanco, 28049 – Madrid, Spain. D. Cáceres. Departamento de Física, Universidad<br />
Carlos III de Madrid, E-28911 Leganés, Spain. F. J. García-López. Centro Nacional de Aceleradores,<br />
Parque Tecnológico Cartuja’93, 41092 – Sevilla, Spain. R. Escobar-Galindo, R. J. Jiménez-Rioboó<br />
and C. Prieto. Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones<br />
Científicas. Cantoblanco, 28049 – Madrid, Spain.<br />
Zirconium oxide is a widely used material because of its heat resistance, low thermal conductivity,<br />
high refractive index and high transparency in the visible and near infrared region, very high chemical<br />
inertness and high laser damage threshold. Due to these properties, its applications can be found<br />
in very different aspects of technology. For instance, zirconia has been applied as thermal barrier<br />
coating (TBC)], optical filters, laser mirrors], oxygen sensors], and solid oxide fuel cells].<br />
TBC’s based on yttria stabilized zirconia (YSZ) films prepared by electron beam physical vapour<br />
deposition (EB-PVD) are candidates for advanced thermal barrier coatings for the new generation of<br />
land-based gas turbines because of the different obtained microstructure respect to other deposition<br />
techniques. The low thermal conductivity magnitude for the films is mainly due to two factors: the<br />
film microstructure and the intrinsic thermal conductivity value. For YSZ system, this second factor<br />
is related with the oxygen defect structure which is induced when Zr 4+ ions are substituted with trivalent<br />
Y 3+ ions giving rise to oxygen vacancies to compensate electrical charge.<br />
Undoubtedly, mechanical properties are of significant importance for TBC and optical applications.<br />
In this work, we present a nanoindentation characterization, where hardness and Young modulus<br />
have been obtained for a set of (Y 2 O 3 ) x -(ZrO 2 ) 1-x thin films prepared by EB-PVD on Si(100) substrates,<br />
in order to study the hardness dependence on the yttria content.<br />
26
JUNE 26 MONDAY MORNING<br />
RIVA-TF-MoM-OR.6 A MINIMALIST SURFACE DECOMPOSITION METHOD AP-<br />
PLIED TO STUDY THE SURFACE CONTROL OF THE Au POLYCRYSTALLINE CO-<br />
LUMNAR FILM GROWTH. E. Rodríguez-Cañas *, and J. L. Sacedón. Instituto de Ciencia de<br />
Materiales de Madrid (CSIC), 28049 Cantoblanco, Madrid, Spain. J. A. Aznárez. Instituto de Física<br />
Aplicada (CSIC), Serrano 144, 28006 Madrid, Spain. A. I. Oliva. Cinvestav del IPN Unidad Mérida,<br />
Dpto. de Física Aplicada, AP 73- Cordemex 97310 Mérida, Yucatán, Mexico<br />
A method based in the minimalist decomposition of surface morphologies is proposed for the study<br />
of surface protrusion terminated growth fronts. The method is applied to the STM morphology images<br />
of Au films thermally evaporated on native SiOx/Si(100) for a wide range of Au thickness (60-<br />
1800 nm). In this case the bulk film morphology corresponds to a columnar competitive growth, and<br />
the growth front is composed of assembled paraboloidal meridian zones. The application of the<br />
method allows the numerical synthesis of height distribution curves by the convolution of the statistical<br />
parameters of the minimalist components. A complete set of statistical parameters, mean values<br />
and fluctuations, and their scaling during the growth are obtained. The slope at the borders of<br />
paraboloidal meridian zones are maintained near constant during the growth and appears as the controlling<br />
growth parameter. In fact its high value and the slope distribution curves can be explained by<br />
an out of equilibrium growth, controlled by steering and interface phenomena at border of the terraces<br />
in addition of an effective Ehrlich-Schwoebel step-edge barrier. The scaling agrees with simulations<br />
in which similar selected slopes are considered. One of the minimalist parameters is the fluctuation<br />
of the columnar height at the film surface, allowing to establish its relation with the other surface<br />
roughness parameters<br />
25
JUNE 26 MONDAY MORNING<br />
RIVA-TF.MoM-OR.5 LOW TEMPERATURE DEPOSITION OF TIB 2 ON X40<br />
CRMOV 5 1 STEEL SUBSTRATE BY DC MAGNETRON SPUTTERING. A. Duarte 1,2 *, B.<br />
Coelho 2 , M. Vila 2 , A.J.S. Fernandes 3 , F. Oliveira 2 , F.M. Costa 3 R.F. Silva 2 . 1 - Laboratório - F. Ramada,<br />
Aços e Industrias, S.A., Apartado 10, 3880-909 Ovar, Portugal. e-mail:<br />
paulo.duarte@ramada.pt 2 - CICECO - Dept. of Ceramics & Glass Engineering, University of Aveiro,<br />
3810-193 Aveiro- Portugal 3 - Dept. of Physics, University of Aveiro, 3810-193 Aveiro- Portugal<br />
Titanium diboride (TiB 2 ) films are being investigated due to their promising uses not only in electronic<br />
devices but also for mechanical purposes. Its excellent corrosion resistance and chemical stability,<br />
as well as high hardness and wear resistance makes TiB 2 particularly suitable for aluminium<br />
processing (e.g. extrusion, die-casting and machining). The major concern about protective coatings<br />
is lack of adhesion to the substrate arising from the high residual stresses developed during film<br />
deposition.<br />
In the present work TiB 2 coatings were produced by non-reactive magnetron sputtering from a TiB 2<br />
target on Orvar Supreme tool steel substrate (also know as AISI H13 premium or X40 CrMoV 5 1).<br />
Two different substrate types were used, similar to those frequently found on the aluminium injection<br />
industry: quenched and tempered/nitrided. The deposition parameters, namely the target/substrate<br />
distance, emission and bias currents, were varied in order to obtain adhered and well<br />
structured films, suiting the substrates composition and microstructure. The coatings were characterized<br />
by X-Ray diffraction, Scanning electron microscopy/EDS, Scratch test and AFM. The results<br />
obtained show that TiB 2 can be grown on the steel substrate at low temperature with high deposition<br />
rate keeping some crystallinity degree. Depending on the experimental parameters it is possible to<br />
coat hot work tool steel with adherent TiB 2 thin films by DC sputtering.<br />
*corresponding author<br />
24
JUNE 26 MONDAY MORNING<br />
RIVA-TF-MoM-OR.4 Ta 2 O 5 THIN FILMS PREPARED BY EVAPORATION AND<br />
IBAD METHODS: CHARACTERIZATION AND WETTING BEHAVIOUR UNDER UV<br />
IRRADIATION. V. Rico, J.P. Espinós, F. <strong>Yubero</strong>, F. Frutos*, A.R. González-Elipe. Instituto de<br />
Ciencia de Materiales de Sevilla (CSIC-Univ. Sevilla). Avda. Américo Vespucio s/n. 41092 Sevilla<br />
(Spain). *Dpto. Física Aplicada I, ETS Ingeniería Informática. Avda. Reina Mercedes s/n. 41012<br />
Sevilla (Spain)<br />
Ta 2 O 5 thin films have been prepared by evaporation from a tantalum oxide precursor and by assisting<br />
the growth of the films by oxygen and nitrogen ion bombardment (IBAD). The obtained thin films<br />
depict different microstructures and optical and dielectric properties. In general, the films prepared<br />
by evaporation have lower refraction indices that those prepared by IBAD. In this case a clear correlation<br />
exists between the ion current and energy and the properties of the films. The trend of dielectric<br />
properties of these thin films agrees with that defined by their optical properties. They also agree<br />
with the microstructrue of the films as determined by SEM. A particular type of films was found<br />
when prepared by evaporation under grazing conditions. These films depict a columnar microstructure<br />
with oblique columns and an extremely high porosity. Refraction indices ranging from 1.7 to 1.2<br />
have been obtained for these thin films.<br />
Another interesting property of these thin films refers to its wetting behaviour under UV light. In literature<br />
there are many papers dealing with the conversion of the TiO 2 surface from partially hydrophobic<br />
into fully hydrophilic by UV irradiation. In this work we also show that Ta 2 O 5 thin films present<br />
a similar behaviour changing from hydrophobic into hydrophilic by illumination. A careful<br />
study of this type of transformation is being carried out as a function of the microstructural and structural<br />
properties of the films. Doping of Ta 2 O 5 thin films with foreign cations and with nitrogen has<br />
revealed to be an effective way to induce a partial change in wetting angle by using visible light for<br />
the illumination.<br />
23
JUNE 26 MONDAY MORNING<br />
RIV-TF-MoM-OR.3 EPITAXIAL MATCHING OF SMALL METALLIC NANO-<br />
CLUSTERS IN LARGE-MISFIT SYSTEMS. J.C. Jiménez-Sáez. Departamento de Física y<br />
Química Aplicadas a la Técnica Aeronáutica, E.U.I.T. Aeronáutica, Universidad Politécnica de Madrid<br />
(UPM), E-28040 Madrid, Spain. E-mail: jc.jimenez@upm.es. A.M.C. Pérez-Martín and J.J.<br />
Jiménez-Rodríguez. Departamento de Electricidad y Electrónica, Facultad de Ciencias Físicas, Universidad<br />
Complutense, E-28040 Madrid, Spain.<br />
The deposition at low energies of Cu and Au nanoclusters on the Au(001) and Cu(001) substrates respectively<br />
is studied by constant temperature molecular-dynamics simulations. Clusters have icosahedral<br />
or Wulff symmetries. Their number of atoms ranges between 13 and 1289. Atomic interactions<br />
are mimicked by a many-body potential based on the tight-binding model. Deposition energy is<br />
of the order of meV/atom and the temperature was 300 K. We have investigated the equilibrium<br />
structure of deposited metallic clusters. The influence of the cluster size and of its shape in the lowenergy<br />
limit on the epitaxial matching has been analyzed. We have taken into account the large lattice<br />
misfit between the cluster and the substrate (12.8% for Cu/Au(001) and 11.35% for<br />
Au/Cu(001)). Previous results show that in cases without misfit the epitaxial growth depends on the<br />
size of the clusters and on the temperature as well. Besides in previous works, we have found a different<br />
elastic behaviour in large clusters when deposition energy is lower or higher than 30<br />
meV/atom. These differences can also induce variations in the epitaxial alignment between cluster<br />
and substrate. The possible matching between both structures has been studied by the common<br />
neighbour analysis, CNA, which classifies the types of bond; by both the structure factor and an epitaxy<br />
factor which asses the degree of adaptation of both lattices; and finally, by a grain analysis<br />
which allows to find out if the deposited-cluster lattice imitates the substrate lattice. Structural properties<br />
of the interface (coherent, semicoherent or incoherent), in addition to the bond distances as a<br />
function of the distance to the interface have been also investigated.<br />
22
JUNE 26 MONDAY MORNING<br />
RIVA-TF-MoM-OR.2 STRAIN ANALYSIS OF PHOTOCATALYTIC TiO 2 THIN<br />
FILMS ON POLYMER SUBSTRATES. C.J. Tavares 1 , S.M. Marques 1 , V. Teixeira 1 , J.O. Carneiro<br />
1 , A.J. Fernandes 2 , E. Alves 3 , A.R. Ramos 3 . 1 Departamento de Física, Universidade do Minho,<br />
4800-058 Guimarães, Portugal. 2 Departamento de Física, Universidade de Aveiro, 3810-193 Aveiro,<br />
Portugal.<br />
3 Instituto Tecnológico e Nuclear, EN 10, 2686-953 Sacavém, Portugal.<br />
ctavares@fisica.uminho.pt<br />
Titanium dioxide (titania) is a well known photocatalyst used in the semiconductor industry due its<br />
efficiency in dissociating pollutant organic compounds. Enhancing the photocatalytic efficiency of<br />
this material has become a major concern for the authors, bearing in mind industrial applications for<br />
general purpose plastics. On an industrial environment, handling of these films often may cause degradation<br />
of the coating, hence the vital importance of also enhancing the mechanical properties. TiO 2<br />
thin films have been deposited by unbalanced reactive magnetron sputtering from a high purity Ti<br />
target in an Ar/O 2 atmosphere, at room temperature, on polymer sheets. X-ray diffraction experiments<br />
revealed for a wide range of deposition parameters that the as-deposited titania thin films are<br />
amorphous. The photocatalytic behaviour of the titania coatings was determined by combined ultraviolet<br />
irradiation and absorption measurements. The observed photo-decomposition of the aqueous<br />
solution (organic pollutant) was measured in the UV/Vis spectrum by the decrease of the maximum<br />
absorbance with irradiation time. Analysis of the absorption data allowed us to obtain the decrease in<br />
concentration as a function of time to be observed. In order to assess the mechanical behaviour of the<br />
as-sputtered films, the film/substrate composite system was loaded unidirectionally using a tensile<br />
testing machine. As the system is stretched, cracks transverse to the loading direction developed in<br />
the film. The number of cracks increased as the applied strain increased, and the relation between the<br />
measured crack density and the applied strain has been used to characterize the film strength and relate<br />
it with the film photocatalytic efficiency.<br />
21
JUNE 26 MONDAY MORNING<br />
RIVA-TF-MoM-OR.1 DETERMINATION OF THE HYDROGEN CONTENT IN<br />
DIAMOND-LIKE CARBON AND POLYMERIC THIN FILMS BY REFLECTION ELEC-<br />
TRON ENERGY LOSS SPECTROSCOPY. J. Rico, F. <strong>Yubero</strong>, J.P. Espinós, J. Cotrino, and<br />
A.R. González-Elipe. ICMSE (CSIC-USE) Amério Vespucio s/n, E-41092 Sevilla, Spain D. Garg.<br />
Air Products and Chemicals, Inc. 7201 Hamilton Boulevard, Allentown, PA 18195-1501, USA<br />
A new non-destructive method to determine hydrogen content in diamond-like carbon and polymeric<br />
thin film materials is developed. The method relies on quantification of the intensity of elastic peak<br />
stemming from the backscattering of electrons with the hydrogen atoms present in the samples as<br />
measured by reflection electron energy loss spectroscopy. Quantitative analysis of the hydrogen<br />
content at the surface of diamond like carbon thin films is achieved by using phenomenological sensitivity<br />
factors of hydrogen against the other atoms with reference to polymeric samples. The validity<br />
of the method is checked with elastic recoil detection measurements. A comparison is also made<br />
with data provided by infrared spectroscopy analysis of the same samples. We estimate that the error<br />
bar in the determination of hydrogen content in the samples is around 20% of the total hydrogen<br />
content.<br />
20
JUNE 26 MONDAY MORNING<br />
RIVA-TF-MoM-INV.1THIN FILM STACKS FOR SPINTRONIC DEVICES: PREPARATION<br />
AND CHARACTERIZATION, P.P.Freitas, S.Freitas and R.Ferreira. INESC MN, Lisbon, Portugal<br />
and Physics Department, Instituto Superior Tecnico, Lisbon, Portugal<br />
Physical Vapour Deposition (PVD) and Ion Beam Deposition (IBD) tools are described as used for the<br />
preparation of spintronic device stacks ( hard disk read heads-spin valve and tunnel junction,<br />
MRAMS, sensor stacks). These tools allow the uniform deposition of multilayered stacks over 8” wafers,<br />
where each individual layer has thickneses down to 1nm. The formation of nm thick AlOx and<br />
MgO barriers, critical to the formation of state of the art tunnel barriers is revised. For device patterning,<br />
both ion-milling and reactive ion etching techniques are used, the latter becoming necessary for<br />
device features below 100nm. The complexity of the magnetic stacks poses several challenges for reactive<br />
etching techniques. Finally, spintronic device examples will be given, starting with magnetic<br />
tunel junction read heads for magnetic data storage at densities beyond 100Gbit/in2, followed by<br />
MRAMS, and different types of field sensors for position, current, and biomedical imaging applications.<br />
19
RIVA-TF SESSION<br />
18
JUNE 26 MONDAY MORNING<br />
ETCHC-MoM-OR.8 BORON IMPLANTATION EFFECTS IN CdDS THIN FILMS<br />
GROWN BY CHEMICAL SYNTHESIS. K. L. Narayanan, M. <strong>Yamaguchi</strong>, Toyota Technological<br />
Institute, 2-12 Hisakata, Tempaku, Nagoya-468 8<strong>51</strong>1, Japan.. R. Lozada-Morales 1 , O. Portillo-<br />
Moreno 2 . Benemérita Universidad Autónoma de Puebla. 1 Departmento de Optoelectrónica, Facultad<br />
de Ciencias Físico-Matemáticas. 2 Facultad de Ciencias Químicas. Puebla, México.O. Zelaya-Angel.<br />
Departamento de Física. Centro de Investigación y de Estudios Avanzados del IPN. P.O.Box 14-740,<br />
México 07360 D.F.<br />
We prepared CdS thin films on ITO/glass substrates using a chemical bath, which were boronimplanted<br />
employing 200 keV beams doses of B + ions in the range 1.0 x 10 15 – 1.0 x 10 16 ions/cm 2 .<br />
The B-doping was successfully carried out, as was proved by the excess of carrier density introduced<br />
in the range 0.8 x 10 18 – 5.4 x 10 18 cm -3 , which was calculated from thermopower measurements that<br />
we made. The Raman spectroscopy results support the assumption that doubly ionized B + (B 3+ ) enter<br />
into the CdS lattice occupying Cd 2+ sites, which create shallow donor levels in the forbidden energy<br />
band gap, in a similar way that it happens with In 3+ ions in CdS.<br />
<strong>17</strong>
JUNE 26 MONDAY MORNING<br />
ETCHC-MoM-OR.7 TUNGSTEN OXIDE WITH DIFERENT OXYGEN CON-TENT:<br />
SLIDING PROPERTIES. T. Polcar, N.M.G. Parreira and A. Cavaleiro a * ICEMS – Grupo de<br />
Materiais e Engenharia de Superfícies, Faculdade de Ciências e Tecnologia da Universidade de<br />
Coimbra – Pólo II, 3030-201 Coimbra, Portugal. * To whom all correspondence should be addressed<br />
(albano.cavaleiro@dem.uc.pt)<br />
Tungsten oxides were studied in the past due to their electro-optical properties (e.g. exhibit electrochromic<br />
behaviour) and, more recently, due to their applications in gas sensor devices. These studies<br />
were particularly focus on the stoichiometric compound WO 3 or WO 3-x (x = 0–1) prepared by different<br />
method. However, it is difficult to prepare tungsten oxide with low oxygen content by equilibrium<br />
process, since the solubility of oxygen in tungsten in such conditions is very low. Therefore, the<br />
non-equilibrium processes must be used being reactive sputtering the most versatile.<br />
The sliding properties of tungsten oxide coatings are not well known. Tungsten trioxide studied by<br />
Lugscheider et al. showed good tribological properties. It is supposed, that sub-stoichiometric tungsten<br />
trioxide can act as a solid lubricant due to presence of the so-called “Magneli” phases. These<br />
phases exhibit a wide range of structures, which leads to the crystallographic shear planes with reduced<br />
binding strength.<br />
In this study, we prepared tungsten oxide by reactive magnetron sputtering with oxygen contents of<br />
13 and 75 at.%. Detailed analyses of the XRD patterns of the former W–O coating showed the b.c.c.<br />
α-W phase. However, the position of the diffraction peak moved to the lower diffraction angles<br />
compared to α-W phase of pure tungsten. This means that oxygen is allocated at the interstitial positions<br />
in the lattice, which leads to higher lattice parameters and induces compressive residual stress.<br />
Concerning the W 25 O 75 coating, the diffraction peaks of XRD pattern suggest a nanocrystalline<br />
structure. At the moment, it is difficult to state that it corresponds to the WO 3 monoclinic (the equilibrium<br />
structure), since the ICDD patterns ofW 20 O 58 , W 5 O 14 , WO 2.90 , and others forms of WO 3 (cubic,<br />
orthorhombic, triclinic) also have diffraction peaks in the same region as the WO 3 monoclinic<br />
phase.<br />
The hardness and Young’s modulus were evaluated by depth sensing indentation. W 87 O 13 and<br />
W 25 O 75 coatings exhibited hardness of 26 GPa (similar to that of pure tungsten) and 7 GPa, respectively.<br />
The coatings displayed a relatively low adhesion (critical load Lc
JUNE 26 MONDAY MORNING<br />
ETCHC-MoM-OR.6 SPUTTERING OF NITRIDES BY LOW-ENERGY IONS OF<br />
DIFFERENT MASSES . S.S. Elovikov, A.S. Mosunov, J. C. Colligon*, Yu.A.Ryzhov,<br />
I.I.Shkarban, V.E.Yurasova, E.Yu.Zykova. Physics Faculty, Moscow State University, Moscow,<br />
119899, Russia. *Manchester Metropolitan University. John Dalton Extension. Manchester M1 5GD,<br />
England, UK<br />
The results of calculations of mass dependence of sputtering yields for nitrides with various ratios<br />
between masses of their components, i.e. BN, AlN, and GaN, are presented. The effect of masses of<br />
bombarding ions with energy from 200 to 2000 eV on sputtering yields, mean energies and energy<br />
spectra of sputtered particles, depths of sputtering origin and number of generations of emitted atoms<br />
for nitrides was investigated and discussed.<br />
Study of sputtering of these nitrides is of interest both for physics of interaction between atomic particles<br />
and solids and from practical viewpoints. BN is an important constructional material due to a<br />
set of useful physical and chemical properties: high hardness and electric strength, good heat conduction,<br />
thermal and chemical stability. AlN is known for strength, elasticity, good heat conduction, and<br />
dielectric strength, and is used in acoustic devices and as a coating in spacecraft components. GaN is<br />
used in light-emitting diodes and other electronic devices. In many of applications, surfaces of nitrides<br />
are subject to various kinds of irradiation, which often leads to degradation of their properties.<br />
Therefore, it is important to know the resistance of these nitrides to the low-energy ion irradiation.<br />
We have used the MD simulation with a mobile single-crystal block of atoms. Polycrystal was simulated<br />
by rotation of single-crystal block through arbitrary angles for every impinging ion. Inelastic<br />
loses were taken into account. Thermal vibrations were considered as uncorrelated. Equations of motion<br />
were integrated using predictor-corrector modified scheme. The interaction potential:<br />
U(r)=a bm (1+a b /r)exp(-r/b),where a bm = 52(Z 1 Z 2 ) 3/4 , a b = (Z 1 Z 2 ) 1/4 /52, b = 0.219Å, Z 1 and Z 2 are the<br />
atomic numbers of the impinging ion and the target atom, respectively. Binding energy E b of surface<br />
atoms was estimated from value of cohesion energy per a bond between atoms in compounds and<br />
was corrected using the experimental results. E b value, thus selected, is: 8.1, 6.8, and 5.4 eV for BN,<br />
AlN, and GaN, respectively.<br />
It was shown that the sputtering yields Y of BN, AlN, and GaN as functions of mass m 1 of normally<br />
incident low-energy ions have a nonmonotonic character with a maximum for small m 1 . For targets<br />
with medium mass of atoms (AlN, GaN), the Y(m 1 ) maximum is observed at m 2 /m 1 = 2 (where m 2 is<br />
the mean atomic mass for compound). In the case of the light-target sputtering (BN), the Y(m 1 )<br />
maximum is at m 2 /m 1 = 1. With increasing E 0 , the Y(m 1 ) maximum is shifted towards heavier masses<br />
and then disappears.<br />
Mean energies Ē 1 of particles sputtered by low-energy ions from AlN and GaN depend nonmonotonically<br />
on m 1 with a maximum at the same values of m 1 as for Y(m 1 ). In BN, Ē 1 has maximum<br />
for the lightest ions.<br />
Energy spectra of a light component of nitrides, which give the main input to sputtering, differ qualitatively<br />
for sputtering by low-energy ions of large and small masses. In the last case, the spectra have<br />
longer high-energy tail and broader maximum of distribution that indicates more favorable conditions<br />
of particle emission with higher energy.<br />
Depths of origin x 0 of sputtered atoms for GaN and AlN increase with decreasing m 1 , particularly<br />
sharp for small m 1 . For greater ion masses, at E 0 = 200 eV, the curves x 0 (m 1 ) reach a constant value at<br />
x 0 ∼ 4 Å for AlN and GaN and slowly grow with m 1 for BN.<br />
Distribution of the sputtering yield over the number of generations of emitted atoms differs significantly<br />
for targets with light and with heavy masses of atoms. So, for BN, these are the tertiary recoils<br />
that give the major contribution to sputtering. In the case of AlN and GaN, the sputtered atoms belong<br />
to primary recoils at lower E 0 and to secondary recoils at higher E 0 .<br />
A special feature of nitride sputtering is that the Y(m 1 ) curves reach saturation for lower values of E 0<br />
than in the case of equivalent single-element target, with atomic mass equal to the mean of the<br />
masses of the two components of the binary compound. This early saturation is caused by the presence<br />
of the lighter component (i.e. N) in nitrides.<br />
We would like to thank the Russian Foundation for Basic Research (grants 05-02-<strong>17</strong>227 and 05-02-<br />
<strong>17</strong>870), and INTAS (grant 03-53-5607) for their support.<br />
15
JUNE 26 MONDAY MORNING<br />
ETCHC-MoM-INV.1 NANOCOMPOSITE HARD COATINGS AS INTERFACE DO-<br />
MINATED MATERIALS. Jörg Patscheider, EMPA, Materials Science and Technology. Überlandstr.<br />
<strong>129</strong>. CH-8600 Dübendorf, Switzerland. e-mail: joerg.patscheider@empa.ch<br />
The introduction of ternary metal nitrides, leading to the coating materials with highly improved<br />
properties, also brought about the discovery of nanocomposite coatings with increased hardness.<br />
Such nanostructured coatings proved successful in promoting hardness, oxidation resistance, improved<br />
wear behavior and other properties relevant for protective coatings. Examples for these materials<br />
are TiN/Si 3 N 4 and TiC/a-C:H. Most nanocomposite hard coatings with well-separated phases<br />
show typically a maximum of the hardness, which can range from 30 GPa to reported values exceeding<br />
60 GPa, as the composition is changed from the pure polycrystalline phase (no amorphous component)<br />
to compositions dominated by the amorphous phase. At the hardness maximum the domain<br />
size of the nanocrystalline phase is below 10 nm and the average thickness of the amorphous layer<br />
separating the nanocrystals, amounts to only one to two atomic bond lengths. The grain size at hardness<br />
maximum for nanocomposites is the same as the single layer thickness in nanomultilayers at the<br />
hardness maximum, suggesting similar hardening mechanisms in the two materials classes. contrast<br />
to multilayers with its sequential deposition of individual layers, nanocomposites are prepared by<br />
codeposition of the involved phases by ion-assisted processes such as unbalanced magnetron PVD,<br />
arc-PVD and PACVD. The quality of the amorphous phase in terms of structural perfection and<br />
thickness is of decisive influence for the performance of the coatings. ). It can be shown that the<br />
chemical nature of the interfaces in TiN/SiN x , despite their inertness, governs the hardness. In some<br />
cases the amorphous phase can act as diffusion barrier (Si 3 N 4 ) for improved thermal stability or as a<br />
solid lubricant (a-C or a-C:H). The amorphous phases in nanocomposites thus cause, apart from the<br />
enhanced hardness, additional effects that are beneficial for their performance.<br />
14
JUNE 26 MONDAY MORNING<br />
ETCHC-MoM-OR.5 OES TIME-RESOLVED CHARACTERIZATION OF THE<br />
DEPOSITION OF MULTILAYERED COATINGS. J. Romero, A. Lousa. Departamento de<br />
Física Aplicada y Optica, Universidad de Barcelona, Avda. Diagonal 647, E-08028 Barcelona, Catalunya,<br />
Spain.<br />
Multilayered structures with nanometric period and manocomposites materials are probably the most<br />
promising alternatives to improve the properties of conventional coatings used for mechanical applications.<br />
Multilayered structures are generally formed by alternatively piling two materials in a periodic<br />
sequence ABABAB….., with a period Λ. Most of the multilayered structures referred in the literature<br />
present mechanical properties that surpass those of their individual materials: increase of<br />
hardness, elastic limit and toughness, and reduction of internal stresses.<br />
We have developed a process for the deposition of multilayered structures by r.f. magnetron sputtering<br />
in a continuous process. A single cathode with a metallic target (Cr) is used, and the alternate<br />
deposition of two materials is achieved by periodically alternating the working gas composition. In<br />
this way, the deposition of metal/nitride, metal/carbide and nitride/carbide multilayers can be<br />
achieved just switching the gas composition between pure Ar and an Ar+N 2 , pure Ar and an<br />
Ar+CH 4 , and Ar+N 2 mixture and Ar+CH 4 respectively.<br />
Cr/CrN multilayered coatings with bilayer periods (Λ) between 120 and 2 nm were deposited by r.f.<br />
magnetron sputtering (13.56 MHz) on Si wafers. The coatings were deposited by reactive sputtering<br />
from a 3-in. diameter pure Cr target (99.99% purity) with a r.f. input power of 100 W and a targetsubstrate<br />
distance of 5 cm. Two independent mass-flow meters controlled each gas flux (Ar and N 2 )<br />
during deposition. Chromium thin films were deposited at 1.0 Pa pure Ar pressure, while chromium<br />
nitride films were produced in Ar–N2 reactive mixtures where the total working pressure was 1.2 Pa<br />
and the nitrogen partial pressure was 0.2 Pa. The Cr/CrN multilayers were deposited alternating both<br />
experimental conditions. Cr and CrN growth rates were 0.8 and 0.6 μm/h, respectively; slow enough<br />
to be able to produce multilayers in the nanometric range<br />
Two nitrogen-related optical signals from plasma de excitation (N 0 2 = 337.1 nm and N + 2 = 391.4 nm,<br />
were found to be the most easily monitored to appreciate changes in N 2 chamber presence. These<br />
two well-defined nitrogen optical emission lines were measured in a time-resolved way during multilayer<br />
deposition in order to monitor nitrogen in chamber residence time responses to the cyclic<br />
switches in its flow.<br />
Exponential time responses were found for cyclic switches, with relaxation times of 1.1 s for the N 2<br />
switch off and 0.9 s for the switch on. These times are less than 4% of the deposition time corresponding<br />
to a bilayer for bilayer periods down to 6-9 nm. Hence, for the multilayers with bilayer<br />
thicknesses higher than 9 nm a well defined multilayer structure is expected, while for values lower<br />
than 6 nm an increasing influence of interlayers and materials mixing is more probable to occur.<br />
The multilayer structure was confirmed by TEM and LA-XRD measurements for bilayer periods<br />
higher than 6 nm, what confirms the in-situ predictions of our OES measurements. The highest hardness<br />
of the coatings set, 28 GPa, was obtained for the coating with the theoretic thinnest bilayer period<br />
(Λ=2.1 nm). This maximum hardness was more than 100% higher than the expected value from<br />
the rule-of-mixtures applied to CrN and Cr coatings<br />
In summary, time-resolved OES plasma measurements are a useful tool to monitoring in-situ the<br />
formation of well defined multilayer structures in a continuous process, with multilayer periods<br />
down to a few nanometres.<br />
13
JUNE 26 MONDAY MORNING<br />
ETCHC.MoM.-OR.4 TRIBO-MECHANICAL PROPERTIES OF CrAlN COATINGS<br />
DOPED WITH YTTRIUM AND ZIRCONIUM. M. Brizuela, D. González, A. García-Luis, P.<br />
Corengia. Fundación INASMET-Tecnalia, Paseo de Mikeletegi 2, 20009 San Sebastián, Spain<br />
The aim of this work is to study the influence of doping with Y and Zr on the mechanical and tribological<br />
behaviour of CrAlN coatings.<br />
CrAlN coatings doped with Y and Zr were prepared on high-speed steel (AISI M2) and Si (100) substrates<br />
by d.c. magnetron sputtering using a commercial equipment (CemeCon® CC800/8) provided<br />
of four targets, two of chromium, one of aluminium, and one of the doping material (yttrium or zirconium)<br />
in a mixture of argon and nitrogen. The influence of different deposition parameters (e.g.:<br />
Ar/N 2 ratio, temperature, doping target power,) on the chemical, mechanical and tribological properties<br />
was analysed.<br />
The mechanical properties of the films was evaluated with a Fischerscope H100 dynamic microprobe<br />
apparatus using a conventional Vickers indenter at loads up to a maximum of 10 mN, to minimise<br />
the influence of the underlying base material. Adhesion testing was carried out with a conventional<br />
VTT scratch test on films deposited on polished M2 steel samples. Critical loads for adhesion were<br />
calculated by optical observation at the first cohesive or adhesive failure of the coating. The friction<br />
and wear tests have been performed in a pin-on-disk apparatus against different counterpart materials<br />
(AISI 52100 steel and Ti6Al4V alloy). Friction coefficients were continuously recorded during the<br />
tests. Wear volume and surface morphology were evaluated on worn areas of coated discs and balls<br />
after testing by means of non-contact laser surface profilometry, scanning electron microscopy<br />
(SEM) and energy dispersive spectroscopy (EDS). Chemical and microstructural properties have<br />
been also investigated by EDS and SEM.<br />
The results show great differences when using different doping elements and deposition conditions.<br />
The role of the amount and type of doping element has been investigated. Hardness values up to 40<br />
GPa have been found in the case of CrAlN coatings doped with yttrium under certain deposition<br />
conditions. The tribological behaviour has also been studied and correlated with the chemical composition<br />
and mechanical properties.<br />
12
JUNE 26 MONDAY MORNING<br />
ETCHC-MoM-OR.3 STUDY OF HYDROGEN AND OXYGEN UPTAKE IN SMART<br />
OPTICAL WINDOWS BASED ON YPd AND MgNiPd THIN FILMS BY GDOES. E. Matveeva,<br />
E.Rayon. Centro MTM, Universidad Politécnica de Valencia, Cami de Vera s/n, E-46022<br />
Valencia Spain. R. Escobar Galindo, J.M. Albella. Departamento Física en Ingeniería de Superficies,<br />
Instituto Ciencia de Materiales, Cantoblanco, E-28049 Madrid, Spain.<br />
The use of smart optical windows based on YPd and MgNiPd thin coatings on transparent glass, has<br />
been extensively studied in the last 15 years due to the possibilities of switching the optical and electrical<br />
properties in a reversible and controlled way. The key of the switching process is based on the<br />
absorption of hydrogen by the reflective metal, converting it to a transparent and semiconductor<br />
metal hydride. In our case, the control of the hydration is carried out by an electrochemical process<br />
in which the hydrogen ions are absorbed onto the metallic cathode. During the anodic discharge, the<br />
hydrogen is released from the metal hydride towards the alkali electrolyte where other reactions may<br />
take place (i.e. metal oxidation). These complex processes are localised in-depth the film thickness<br />
(approximately 200 nm) and at the interfaces. Incontrollable oxidation of the active films during anodic<br />
discharge depending on the position in the film of the oxide formed can block the hydrogen diffusion<br />
process and reduce hydrogenation limiting the lifetime of the devices. Therefore, it is crucial<br />
to have a detailed knowledge of the mechanisms of hydrogen and oxygen uptake and release in the<br />
films. Most of the previous studies has been done by X-ray and infrared characterisation techniques,<br />
but they do not provide depth profile information.<br />
As an alternative, in this work, we have made use of the high elemental sensitivity and nanometre<br />
depth resolution of radiofrequency Glow Discharge Optical Emission Spectroscopy (rf-GDOES) to<br />
study the depth profiles of the elements present in the films. In particular, the hydrogen and oxygen<br />
uptake and release was followed in samples subjected to different charge and discharge processes.<br />
GDOES measurements were performed after each electrochemical experiment (charging and discharging),<br />
whose kinetics was recorded,. The most representative observations of the GDOES results<br />
were: i) The resolution of the layer structure of the film (5 nm Pd/metal layer/glass), ii) the detection<br />
and monitoring of hydrogen migration in and out of the film during loading and release cycles and<br />
iii) the revelation of the enhanced oxidation of the film after an anodic discharge. The relation of<br />
these observations with the performance of the devices will be further discussed in this paper.<br />
11
JUNE 26 MONDAY MORNING<br />
ETCHC-MoM-OR.2 COMPUTER DESIGN OF OPTICAL COATINGS IN SYSTEMS<br />
WITH CONTINUOUSLY VARYING REFRACTIVE INDEX. J.F. Trigo. Departamento de<br />
Energía, CIEMAT, Avda. Complutense 22, E-28040 Madrid, Spain. I. Preda, S. Palacín, A. Gutiérrez<br />
and L. Soriano. Departamento de Física Aplicada C-XII, Universidad Autónoma de Madrid, Cantoblanco<br />
E-28049 Madrid, Spain<br />
A simple computerized method for the calculation and refinement of a multilayer discrete optical design<br />
has been used to test the accuracy and stability of the given solution with continuously varying<br />
refractive index systems as compared with usual high-low (HL) bilayer systems.<br />
Motivated for the study of nanostructured mixed materials, which results in a controlled variation of<br />
the index of refraction, a code for multilayer Reflectance-Transmittance calculation has been modified<br />
to treat the problem of continuously varying refractive index. An example of sinusoidal variation<br />
has been studied and compared with discrete HL multilayer to produce a step filter. Also the stability<br />
of the filter Transmittance against a random dispersion of the layers thickness has been compared.<br />
The conclusion of the comparison was that the bilayered model was better in producing sharp step<br />
filters but this performance was rapidly destroyed by a random dispersion up to a 20% of the layers<br />
thickness whereas the sinusoidal continuous variation of the refractive index filter remained stable in<br />
the same condition. This indicates that the design calculated for these continuous systems would be<br />
more easily produced and reproduced in batch industrial processes.<br />
On the other hand, the calculation and refinement of the continuous optical coating is much more<br />
time consuming with our method so considerable effort has been done to improve the code in this<br />
sense.<br />
10
JUNE 26 MONDAY MORNING<br />
ETCHC--MoM-OR.1 ROOM TEMPERATURE PL CHARACTERIZATION OF MI-<br />
CRO- AND NANOCRYSTALLINE DIAMOND GROWN BY MPCVD FROM AR/H 2 /CH 4<br />
MIXTURES M.A. Neto. CICECO Dept. of Ceramics & Glass Engineering, University of Aveiro,<br />
Portugal. A.J.S. Fernandes. Dept. of Physics, University of Aveiro, Portugal. R.F. Silva. CICECO-<br />
Dept. of Ceramics & Glass Engineering, University of Aveiro, Portugal. F.M. Costa. Dept. of Physics,<br />
University of Aveiro, Portugal<br />
Since the first successful efforts to synthesize diamond by chemical vapour deposition (CVD) in the<br />
mid-eighties, many technical and scientific improvements have been achieved. Growth rates, quality<br />
grade and size up-scaling put CVD diamond into the industrial reality for mechanical and thermal<br />
applications, among others. Until recently, most of the available products were based on microcrystalline<br />
CVD diamond (MCD) thick films for brazing or, alternatively, directly coated thin films on<br />
tool substrates. Lately, nanocrystalline diamond (NCD) emerged as an alternative to the microcrystalline<br />
material for some applications, mainly due to its enhanced smoothness and electronic properties.<br />
Structurally, NCD is composed by small (2-100nm) crystallites frequently surrounded by a nondiamond<br />
carbon matrix, resulting in a non-columnar growth. In opposition, MCD crystals grow in a<br />
columnar structure according to the Van der Drift model with much lower grain boundary densities.<br />
In this work, a photoluminescence (PL) study at room temperature was accomplished as a complement<br />
to well established structural and morphological characterization techniques such as µ-Raman,<br />
FTIR, XRD, XPS or SEM. Considering the wide electronic band gap of pure diamond (5.45eV), the<br />
near UV excitation (325nm) from an HeCd laser source was selected. The observed NCD and MCD<br />
samples were obtained by microwave plasma (MPCVD) from hydrogen poor Ar/H 2 /CH 4 mixtures. A<br />
broad violet band dominates the PL spectra of both sample types, evidencing however a stress related<br />
wavelength shift between them. The well known 1.681 eV peak related to the Si-vacancy color<br />
centre is much more pronounced in the MCD samples, showing that silicon is incorporated in the<br />
diamond lattice. In the case of NCD, the absence of the above mentioned peak suggests that Si is<br />
probably trapped by the amorphous carbon phases at the grain boundaries. The samples were further<br />
structurally and morphologically characterized by micro Raman spectroscopy, XRD and SEM.<br />
9
ETCHC SESSION<br />
8
PARALLEL SESSIONS<br />
7
JUNE 26 MONDAY MORNING<br />
MoM-Pl.1 QUALITY VACUUM MEASUREMENTS FOR PROCESS APPLICATIONS.<br />
Charles R. Tilford, Independent Consultant, Gaithersburg, MD USA, CharlesTilford@Verizon.net<br />
Vacuum technology is a rapidly maturing field with many industrial applications. This does not<br />
mean an end to vacuum science investigations and technical development. However, it does mean<br />
an increasing focus on the needs of large-scale processes, whether they are producing energetic particles<br />
or consumer products. In addition, more of a focus on quality—fitness for purpose—whether<br />
the vacuum contribution is hardware, measurements, or techniques. This process is already underway—witness<br />
the change in vacuum equipment to meet the particular needs of the semiconductor<br />
processing industry. But much more needs to be done and the vacuum community will be increasingly<br />
called upon to apply their expertise outside of their own field of interest. There are many ways<br />
of doing this, training courses and documentary standards for example. But there are times when it<br />
is most useful for the vacuum specialist to directly collaborate with equipment manufacturers and<br />
users of vacuum-technology. Because of the large variety of applications, and different backgrounds<br />
of the users, this process can be difficult. But the benefits of such collaborations can be very great,<br />
and such collaborations are already quite common in the vacuum equipment area. With the growing<br />
complexity of vacuum processes and the importance of measurements for process control, it is probable<br />
that there will more instances where the specialized knowledge and experience of vacuum<br />
measurement specialists will be a welcome addition.<br />
Direct participation in problem solving outside of their own field will be a new experience for some<br />
vacuum measurement experts. But this is just the latest step in the evolution of vacuum measurements<br />
and standards. This field started with the need to measure ever-lower pressures. Accuracy, to<br />
the extent that it was ever considered, generally was with respect to a local reference—the “magic”<br />
reading that produced an acceptable product, or agreement with a “standard” gauge. With the<br />
growth of global trade and manufacturing this is no longer acceptable and vacuum measurements<br />
must now be established with respect to the internationally accepted measurement system (the SI).<br />
A great deal of progress has been made in establishing primary vacuum standards and calibration<br />
systems, and ensuring international compatibility. But while proper calibration of an instrument with<br />
respect to the SI is necessary, it is not sufficient to ensure that quality measurements are available for<br />
the end use. It is also necessary that the calibrated instrument be stable, environmental influences<br />
are understood and properly accounted for, the end user is able to properly operate the instrument,<br />
and the entire process is affordable. Vacuum measurements are also especially susceptible to application<br />
effects; where the vacuum instrument is located within the process can be critical, as can the<br />
mix of gases present. The vacuum specialist cannot resolve all of these issues, but in many cases<br />
their participation will be essential if effective solutions are to be devised.<br />
This talk will include a broader discussion of these issues, some examples of past efforts of this type,<br />
and a discussion of vacuum instrumentation characteristics that should be considered in resolving<br />
real world problems. This will include discussion of reference leaks, Spinning Rotor Gages and Residual<br />
Gas Analyzers.<br />
6
PLENARY<br />
5
MONDAY MORNING<br />
4
JUNE 26, 2006<br />
Morning Session<br />
INDEX<br />
ETCHC 9<br />
RIVA-TF 20<br />
WS-18 29<br />
JUNE 26, 2006<br />
Afternoon Session<br />
ETCHC 36<br />
RIVA-TF 41<br />
WS-18 50<br />
JUNE 27, 2006<br />
Morning Session<br />
JS1: WS-20- RIVA-ETCHC 57<br />
WS-18 66<br />
JUNE 27, 2006<br />
Afternoon Session<br />
JS1: WS-20- RIVA-ETCHC 74<br />
WS-18 80<br />
JUNE 28, 2006<br />
Morning Session<br />
JS2: WS-20-ETCHC 97<br />
WS-18 105<br />
RIVA-SS 87<br />
JUNE 28, 2006<br />
Afternoon Session<br />
Poster Session : RIVA-ETCHC-WS-20 111<br />
Plenary Lecturers<br />
Ch. Tilford 6<br />
J. Verhoeven 55<br />
H. Högberg 85<br />
3
FOREWORD<br />
The present book contains de abstracts of plenary lecturers, invited and oral<br />
presentations as well as poster presentations. The abstracts have been distributed<br />
according to their scheduled presentation of the corresponding session<br />
of the Conference.<br />
The abstract correspond to the main parallel activities of:<br />
6TH IBERIAN VACUUM MEETING, RIVA-6<br />
4th EUROPEAN TOPICAL CONFERENCE ON HARD COATINGS, ETCHC-4<br />
WS-18: VACUUM MEASUREMENT, LEAK DETECTION AND CALIBRATION AND<br />
VACUUM QUALITY CONTROL<br />
WS-20: OPTICAL AND DECORATIVE COATINGS<br />
Two join sessions has been scheduled the first one to present aspects of the<br />
Thin Films with the workshop devoted to Optical and Decorative Coatings and<br />
the second one is related with hard coatings and tribology.<br />
Presentations related with vacuum measurements has been organised in a<br />
workshop with aspects of the leak detection and vacuum quality control.<br />
Edited by the Asociación Española del Vacío<br />
Madrid. Spain<br />
The Organising Committee and the Editor are grateful to the authors for<br />
their contributions, specially the significant contributions of the Portuguese<br />
scientific community. We also thank the International Programme Committee<br />
for their work in the reviewing of the abstract. A special acknowledge is<br />
to Professor Ángela Calvo for her work in preparing of the local arrangement.<br />
We also thank the University of Salamanca for all the facilities.<br />
José L. de Segovia<br />
Editor<br />
2
Sigilum Universitatis Studii Salamantini<br />
6TH IBERIAN VACUUM MEETING, RIVA-6<br />
12 REUNIÓN ESPAÑOLA DEL VACÍO Y SUS APLICACIONES, REVA-12<br />
REUNIÂO PORTUGUESA DE VÁCUO E SUAS APLICAÇÕES, RIVA-6<br />
4th EUROPEAN TOPICAL CONFERENCE ON HARD COATINGS, ETCHC-4<br />
WS-18: VACUUM MEASUREMENT, LEAK DETECTION AND CALIBRATION AND<br />
QUALITY CONTROL IN ADVANCED INDUSTRIES<br />
WS-20: OPTICAL AND DECORATIVE COATINGS<br />
June 26-30, 2006<br />
Abstract Book<br />
EDITORS:<br />
José L. de Segovia<br />
Instituto de Ciencia de Materiales de Madrid. CSIC. ES<br />
O. Teodoro<br />
Iniversidade Nova de Lisboa. PT<br />
1