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Substrate and Deposition Time Effect on the Hydrophilicity of the Hydrothermally grown TiO 2 films Κ. Vlachou, 1 G. Kalogerakis, 1 D. Vernardou, 1,2,3* E. Stratakis, 1,4,5 G. Kenanakis, 2,3,6 E. Koudoumas 2,4 and N. Katsarakis 2,3,5 1 Department of Materials Science and Technology, University of Crete, 710 03 Heraklion, Crete, Greece 2 Center of Materials Technology and Laser, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete, Greece 3 Science Department, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete, Greece 4 Electrical Engineering Department, Technological Educational Institute of Crete, 710 04 Heraklion, Crete, Greece 5 Institute of Electronic Structure and Laser, Foundation for Research & Technology-Hellas, P.O. Box 1527, Vassilika Vouton, 711 10 Heraklion, Crete, Greece 6 Department of Chemistry, University of Crete, 710 03 Heraklion, Crete, Greece *Dimitra Vernardou, e-mail: dimitra@iesl.forth.gr Titanium (IV) oxide films were deposited on Corning and ITO substrates for deposition times ranging from 1 hr to 50 hr by a hydrothermal growth technique, using titanium (IV) isopropoxide, isopropanol and MilliQ water as precursors. The structural, morphological and optical properties of the films were evaluated by X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM) and UV-Vis spectroscopy respectively. The dark and photoinduced hydrophilicity of the films were evaluated by means of contact angle measurements. It is demonstrated that as-deposited TiO 2 films grown at 95 o C for deposition period of 50 hr showed a light-induced transition to superhydrophilicity reaching a nearly zero contact angle. This transition is reversible after dark storage of the UV-irradiated films. The relationship between material properties and hydrophilic characteristics is discussed in the framework of the application of the grown films for self-cleaning window coatings. 207
Modification of Perlite Cementitious Samples with Nanostructured Titania A.I. Kontos 1 , A.G. Kontos 1,2 , M. Fardis 3 , S. Kourkoulis 2 , V. Tsitsias 1 , G. Papavassiliou 3 and P. Falaras 1* 1 Institute of Physical Chemistry, NCSR Democritos, 15310, Aghia Paraskevi, Athens, Greece 2 Faculty of Applied Sciences, National Technical University, 157 80 Athens, Greece 3 Institute of Materials Science, NCSR Democritos, 15310, Aghia Paraskevi, Athens, Greece *papi@chem.demokritos.gr Modified cementitious construction materials such as paints, mortars, concrete etc. have recently attracted much interest, taking advantage of the photoinduced properties of semiconducting nanoparticulate additives [1]. TiO 2 has proved to be very effective in the reduction of pollutants such as NO x , aromatics, ammonia, and aldehydes as well as bacteria both in air-solid and liquid–solid interface [2]. For light irradiation of TiO 2 in the near UV, with energy above its band gap, E g =3.2 eV, an electron is injected from the valence band to the conduction band, leaving a hole in the valence band. The photogenerated electrons then react with molecular oxygen (O 2 ) to produce superoxide radical anions (٠O 2 - ), and the photogenerated holes react with water to produce hydroxyl (٠OH) radicals [3]. These highly reactive species are able to decompose a variety of pollutants and kill microorganisms (bacteria and viruses). The new technology of TiO 2 modified cements aims in the maintenance of the aesthetic characteristics of concrete structures, particularly those based on white Portland Cement (PC) by degrading the accumulation of colored organic species which are responsible for discoloration and dirt. Expanded Perlite (EP) is a light, insulating and fire-resisting material that used as an additive to cement, and Portland cement with many construction applications. One of the most important is the production of insulating roof decks. Furthermore, unexpanded crude perlite (CP) is also used as a mineral additive of cement [4]. For the first time, in this report, we present the photocatalytic modification of perlite cementitious materials and test them for their efficiency in maintaining clean surfaces. Properties, such as the type of the perlite-cement mixture slurries and the compression strength, as well as processes, like the hydration and photocatalysis, have been investigated. The cementitous samples were prepared mixing CP and EP perlite (S&B Industrial minerals S.A.) with PC (Hercules Cements Co, 42.5N) and were photocatalytically modified using TiO 2 (Degussa P25). The proportions of materials used for the preparation of CP (P091) concrete were water/PC=0.4, CP/PC=0.4 [4] and TiO 2 /(TiO 2 +PC)=0.05 [5]. For the preparation of the lightweight expanded perlite concrete, the water/PC content ratio was changed to 0.96; all the rest proportions were kept the same as before. This water/PC proportion is usually applied in commercial products [6]. Two EP samples were examined, with grain size 0.3 (P072) and 4.75 mm (P082). The hydration process of the cement samples was followed by the nuclear magnetic resonance (NMR) relaxometry method. 1 H NMR measurements were carried on a Brucker MSL spectrometer operating at 200 MHz. T 1 relaxation measurements were done by applying a single 90 o pulse and recording the relaxed magnetization at various time steps, after. Compressive strength tests were performed on mortar discs of aspect ratio 2, height 100 mm, under quasi static displacement control conditions. Results concerning the fracture stress are given in Table I. Addition of Degussa P25 and CP in the cement blend samples improves the mechanical strength, while the light cementetious samples present an order of magnitude lower compressive strength than the others. The conclusion concerning the other mechanical properties, like Poisson’s ratio, modules of elasticity and strain energy density are of similar nature. Comparison of the different hydration kinetic graphs can give important information on the hydration and physical properties of the materials as well as the influence of perlite and TiO 2 on the hydration process. The dependence of T 1 upon the hydration time for Portland Cement (PC) and the modified sample (PC+P25) is shown in fig. 1. All graphs are of similar shape and present a step like progression where the three periods of hydration (starting, acceleration and hardening period) are well distinguished. The critical parameters which can be extracted from the graphs are a) the starting (t s ) and the ending time (t e ) of the acceleration period b) the plateau T 1 value in the initial period (T 1 in ) and c) the T 1 (T 1 fin ) level of steady state response in the hardening period. Sample σ (MPa) t s (hours) t e (hours) T in 1 (msec) T fin 1 (msec) PC 20.36 2.4 28 230 3.1 PC +TiO 2 22.30 1.3 23 140 2.5 CP+PC 25.38 2.1 32 195 3.5 CP+PC+TiO 2 16.20 1.5 19 140 2.5 EP(P072)+PC 2.36 1.7 37 430 4 EP(P072)+PC+TiO 2 1.37 2.4 21 450 5 Table 1. Compression strength and hydration kinetic characteristics of various cementitious samples with portland cement, expanded or crude perlite and TiO 2 . Kinetic results deduced by NMR T 1 relaxation measurements. The hydration characteristics of the reference PC and the CP+PC samples, shown also in Table 1, are quite similar. The addition of TiO 2 in PC or the CP+PC mixture significantly accelerates the whole process and shifts the hydration curve in the log time scale (t s and t e decrement). Similar effect was observed in PC+TiO 2 samples [2] and indicates interactions between 208
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XXIII ΠΑΝΕΛΛΗΝΙΟ ΣΥΝΕ
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Κοιτώντας τα πρακτ
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ΕΠΙΤΡΟΠΕΣ Οργανωτι
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ΠΡΟΓΡΑΜΜΑ ΣΥΝΕΔΡΙΟ
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21. Οργανικά τρανζίσ
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15:30 15:45 16:00 16:15 16:30 16:45
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41. Modeling and quantitative phase
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Ανοιχτή Συνεδρία «
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«NανοΥλικά και Νανο
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New materials and MOS device concep
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Reliability Characteristics of Rare
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Ο λόγος των ταχυτήτ
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Thus the mean R In-In is expected t
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FIG 1. Schematic representation of
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με 0.80 eV στη διεπιφά
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Εντοπισµός Φορέων
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Παρασκευή και Xαρακ
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Electrical Spin Injection from Fe i
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Electrical Spin Injection of Spin-P
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References [1] CH Lee, J. Meteer, V
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Σχήμα 1: Φωτογραφία
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SEM Image Layout Simulation Εικ
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Μελέτη Ατελειών Σε
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Facet-Stress-Driven Ordering in SiG
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νανοκρυσταλλίτης (a
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Σχήµα 1. Εικόνες περ
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Σχήµα 1. Εικόνες περ
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Οι δομές που αναπτύ
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Raman Intensity (10 -50 cm 3 ) 1,2
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Μελέτη της Επίδρασ
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Annealing Induced Dissociation of N
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`Εναπόθεση με Παλμι
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Μελέτη της Χημείας
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Ανάπτυξη Νέων Μεσο
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Application of Thermal Quadrupoles
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Στοχαστική προσομο
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Νανοτραχύτητα κατά
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Ευαισθησία και Δια
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Optical Properties of CuIn 1-x Ga x
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ανοπτημένο με λέιζ
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Στο σχήμα 3 φαίνοντ
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Id (mA) -0,3 -0,2 -0,1 Vg=0 Vg=-1 V
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Strained-Si Si 1-x Ge x graded Si 1
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Fig. 1. Laser mask movement during
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forwarded to the back interface dur
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Σχήμα 2: Εκθετική εξ
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V th (V) G m,max /G m,max0 (%) I d
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C/ C ox 1,0 0,8 0,6 0,4 0,2 0,0 -4
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και Ta 2 O 5 , των οποίω
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κατασκευή της. Η πα
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ΔP (mW) 12 10 8 6 4 2 0 0 500 1000
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υπολογίσουμε θεωρη
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Σχήμα 2 Σύστημα ηλε
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Μελέτη των Μηχανισ
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Ανάπτυξη και Μελέτ
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Structure and Magnetic Properties o
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Δομή και Μαγνητικέ
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Μετρήσεις Ειδικής
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Further, almost all of the observed
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g-factor 2.019 2.016 2.013 2.010 2.
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ρυθμό 4 C.min -1 , έπειτ
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ΜΕΛΕΤΗ ΤΟΥ ΦΑΙΝΟΜΕ
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Νέοι Εξαφερίτες Ba µ
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Crystal Structure of a new Supramol
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Magnetic Phase Transition in Synthe
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Συσχέτιση πλαστική
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Μετασχηματισμοί φά
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Μελέτη της Επίδρασ
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Resonant Spin Transfer Torque in Do
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3 η Προφορική Συνεδ
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technology, and e-beam lithography.
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ecause it reduces the calculation o
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Υπολογισμός Υψηλής
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The thermodynamic average is obtain
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ΑΠΟΤΕΛΕΣΜΑΤΑ Στην
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προερχόµενη είτε α
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Combining Magnetism and Ferroelectr
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υµένια LCMO/STO (100) πολ
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Our scheme is illustrated in Fig. 1
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[6] . Η μελέτη του υλι
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τα πειραµατικά µας
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συµπύκνωµα. Αυτό επ
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και αναδεικνύει τρ
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P P P P P power P copolymers P and
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Αυτο-οργάνωση και Μ
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Viscoelastic Response of Micelles w
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Διηλεκτρική απόκρι
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Light - induced Reversible Hydrophi
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Οι παραπάνω τρεις κ
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Page 185 and 186: Structure and Dynamics of Branched
Page 187 and 188: ∆οµή και ∆υναµική
Page 189 and 190: Επίδραση της Τοπολ
Page 191 and 192: (α) (β) Σχήμα 2: (α) Απε
Page 193 and 194: Figure 3. Generation 4 PAMAM-H 2 O
Page 195 and 196: Από όλα τα παραπάνω
Page 197 and 198: Το PHEGMA είναι άμορφο
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Page 201 and 202: The nonlinear optical response of A
Page 203 and 204: νανοσωµατίδια. Όπω
Page 205 and 206: Bioactive Glass/Nanodiamonds system
Page 207 and 208: Energy Loss Rates of Hot Electrons
Page 209 and 210: Σύνθεση και Χαρακτ
Page 211 and 212: μπορεί να ερμηνευτ
Page 213 and 214: Nανοσυνθέτα Εποξει
Page 215 and 216: [1] S. Iijima, Nature 354, 56 (1991
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Page 227 and 228: Συναπόθεση Cr - Ni σε
Page 229: Investigation of the Structural, Mo
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Page 237 and 238: Preparation of YSZ Solid Electrolyt
Page 239 and 240: Σύνθεση, Ανισοτροπ
Page 241 and 242: Μελέτη ανθρώπινων
Page 243 and 244: Local Coordination of Zn and Fe in
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Page 247 and 248: Αλκαλική Σύνθεση κ
Page 249 and 250: Μηχανικές Iδιότητε
Page 251 and 252: The Influence of Thermal Aging on t
Page 253 and 254: Modeling and quantitative phase ana
Page 255 and 256: Συμβολή στη Συντήρ
Page 257 and 258: Κρυσταλλική Συµπερ
Page 259 and 260: Σύνθεση Στερεών ∆ι
Page 261 and 262: Fabrication and Characterization of
Page 263 and 264: ∆ιερεύνηση δυνατό
Page 265 and 266: Συγκριτική αξιολόγ
Page 267 and 268: 6 η Προφορική Συνεδ
Page 269 and 270: Ηλεκτρομαγνητική Α
Page 271 and 272: Φασματοσκοπική Μελ
Page 273 and 274: Thermal and Electrical Properties o
Page 275 and 276: Structure, Mechanical, and Optoelec
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Νέα Αυτό-οργανούμε
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A Physical Model to Interpret the E
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FIR study of Ag x (As 33 S 33 Se 33
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Mελέτη Μεικτών Γυαλ
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The Structural Role of Fe and Zn in
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ΕΥΡΕΤΗΡΙΟ ΣΥΓΓΡΑΦΕ
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Κομπίτσας Μ…………
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ΕΥΡΕΤΗΡΙΟ ΣΥΓΓΡΑΦΕ
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W Watson I.M………………4 Weg
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xxiii ÏÎ±Î½ÎµÎ»Î»Î·Î½Î¹Î¿ ÏÏÎ½ÎµÎ´ÏÎ¹Î¿ ÏÏÏÎ¹ÎºÎ·Ï ÏÏÎµÏÎµÎ±Ï ÎºÎ±ÏÎ±ÏÏÎ±ÏÎ·Ï & ÎµÏÎ¹ÏÏÎ·Î¼Î·Ï ...