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Thick Films (thick + film)
Kinds of Thick Films Selected AbstractsPreferred Orientation of Bi4Ti3O12 Thick FilmJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2007Yoshiaki Kinemuchi The preferred orientation of thick films prepared by paste printing is rarely observed because of their bulky polycrystalline nature. We found that a Bi4Ti3O12 thick film with a thickness of ca. 20 ,m showed c -axis-preferred orientation. Initially, the texture of the screen-printed film was found to have a random orientation, which was attributed to the equiaxed particle shape of the raw powder synthesized by the co-precipitation method. During subsequent heating, c -axis orientation emerged in which the degree of orientation was proportional to the film density. Analysis of the orientation distribution revealed that the progress of texturing was attributed to the film deformation, indicating that anisotropic shrinkage and morphological changes in particles during heating influenced the preferred orientation. [source] NiZnCu Ferrite Thick Film with Nano Scale Crystallites Formed by the Aerosol Deposition MethodJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2004Maxim Lebedev This paper describes the magnetic properties of NiZnCu ferrite film deposited at room temperature by an aerosol deposition method (ADM). The thickness of the film was 6 ,m and the deposition rate was estimated as 2 ,m/min. The microstructure of as-deposited at room temperature films consists of randomly oriented nanocrystallites with a size of 20 nm. As-deposited and annealed films exhibited the following magnetic properties: intensity of magnetization Ms= 0.147 T (117 emu/cm3), coercivity Hc= 40.58 kA/m (510 Oe); and Ms= 0.3 T (250 emu/cm3), Hc= 14.95 kA/m (188 Oe), respectively. [source] Textured Microstructure and Dielectric Properties Relationship of BaNd2Ti5O14 Thick Films Prepared by Electrophoretic DepositionADVANCED FUNCTIONAL MATERIALS, Issue 7 2009Zhi Fu Abstract An alternative approach to tailor the temperature coefficient of permittivity (TC,r) of high Q dielectric BaO,Re2O3,TiO2 (Re: rare earth elements) thick films is presented. 10- to 80-µm-thick BaNd2Ti5O14 (BNT) films are fabricated by electrophoretic deposition on Pt foils under different processing conditions. Observed anisotropic grain growth is facilitated by constrained sintering. The increase of the sintering temperature increases markedly the aspect ratio of the grains, decreases the dielectric permittivity and TC,r changes from ,114 to +12,ppm °C,1. By controlling the sintering temperature, near-zero TC,r, high Q thick films can be fabricated with 45,<,,r,<,70. These findings are of technological relevance since they demonstrate that control of substrate constraint and sintering conditions can be used to control grain anisotropy and thus microwave properties of the BaO,Re2O3,TiO2. The thick films facilitate scaling to small device sizes for high frequency operation. Similar observations are expected in other microwave systems thus opening further technological opportunities. [source] Fabrication of Microcantilever Sensors Actuated by Piezoelectric Pb(Zr0.52Ti0.48)O3 Thick Films and Determination of Their Electromechanical Characteristics,ADVANCED FUNCTIONAL MATERIALS, Issue 12 2005H. Park Abstract The integration and the device realization of Pb(Zr,,Ti)O3 (PZT) thick films on Si substrates are known to be extremely difficult because the processing temperature of the PZT thick film is close to the melting point of Si. However, PZT thick-film devices on Si warrant attention as they are appropriate for biological transducers; they generate large actuating forces and have a relatively high sensitivity for mass detection, especially in liquids. In this study, Pb(Zr0.52Ti0.48)O3 thick-film cantilever devices are successfully fabricated on a Pt/TiO2/SiNx/Si substrate using a screen-printing method and microelectromechanical systems (MEMS) process. Elastic and electromechanical properties such as the Young's modulus and transverse piezoelectric coefficient are determined from microstructural and electrical analyses for further mechanical study. The calculated Young's modulus of the thick film, 53.9,±,3.85,GPa, corresponds to the resonant frequency obtained from the measured harmonic oscillation response. The transverse piezoelectric constant, d31, of ,20.7 to ,18.8,pC,N,1 is comparable to that of a dense thin film. These values promise the possibility of determining the resonance properties of a thick-film cantilever by designing its structure and then simulating the harmonic oscillation response. Using the PZT thick-film cantilever, a strong harmonic oscillation with a quality (Q) factor of about 23 is demonstrated in water. The observation of strong harmonic oscillation in liquid implies the feasibility of precise real-time recognition of biomolecules using PZT thick-film cantilevers. [source] Dielectric Properties of Electrophoretically Deposited and Isothermally Pressed BaTiO3 Thick FilmsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2008Ling Zhang Thick BaTiO3 films were prepared on platinum metallic foils by the electrophoretic deposition (EPD) technique using BaTiO3 nanoparticles. In order to increase the density of the thick film, the green film was pressed under an isostatic pressure of 200 MPa before high-temperature sintering. The microstructures of deposited films were examined using X-ray diffraction and scanning electron microscopy techniques. Dielectric properties of the thick films were investigated. As the films grow thicker, the dielectric constant increases gradually and the dielectric loss decreases slightly. The experimental results indicate that isostatic pressing is an effective method to process thick films with dense microstructure and better dielectric properties. [source] Preparation of Highly Dense PZN,PZT Thick Films by the Aerosol Deposition Method Using Excess-PbO PowderJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2007Jong-Jin Choi Lead zinc niobate,lead zirconate titanate thick films with a thickness of 50,100 ,m were deposited on silicon and alumina substrates using the aerosol deposition method. The effects of excess lead oxide (PbO) on stress relaxation during postannealing were studied. Excess PbO content was varied from 0 to 5 mol%. The as-deposited film had a fairly dense microstructure with nanosized grains. The films deposited on silicon were annealed at temperatures of 700°C, and the films deposited on sapphire were annealed at 900°C in an electrical furnace. The annealed film was detached and cracks were generated due to the high residual compressive stress and thermal stress induced by thermal expansion coefficient mismatch. However, the film deposited using powder containing 2% of excess PbO showed no cracking or detachment from the substrate after the postannealing process. The PbO evaporation at elevated temperature during the postannealing process seemed to have reduced the residual compressive stress. The remanent polarization and relative dielectric constant of the 50 ,m thick films annealed at 900°C were 43.1 ,C/cm2 and 1400, respectively, which were comparable with the values of a bulk specimen prepared by a powder sintering process. [source] Thermal Softening Behavior and Application to Transparent Thick Films of Poly(benzylsilsesquioxane) Particles Prepared by the Sol,Gel ProcessJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2001Atsunori Matsuda Thick films of poly(benzylsilsesquioxane) (BnSiO3/2) particles, prepared by the sol,gel process, were deposited onto indium-tin-oxide-coated glass substrates by electrophoresis for the application to the micropatterning of the films. BnSiO3/2 particles were thermally softened and sintered at ,50°C, which was above the glass transition temperature of the particles. The films prepared by the electrophoretic sol,gel deposition consisted of aggregates of particles with diameters of 0.2,1 ,m and were opaque. The film shrank from 2.5 ,m to 1.4 ,m in thickness and became transparent upon sintering of the particles during heat treatment at temperatures >100°C. [source] ChemInform Abstract: Growth of Epitaxial MgB2 Thick Films with Columnar Structures by Using HPCVD.CHEMINFORM, Issue 9 2008Won Kyung Seong Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Effect of AlN doping on the growth morphology of SiCCRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2009N. B. Singh Abstract AlN doped SiC films were deposited on on-axis Si-face 4H-SiC (0001) substrates by the physical vapor transport (PVT) method. Thick film in the range of 20 ,m range was grown and morphology was characterized. Films were grown by physical vapor deposition (PVD) in a vertical geometry in the nitrogen atmosphere. We observed that nucleation occurred in the form of discs and growth occurred in hexagonal geometry. The X-ray studies showed (001) orientation and full width of half maxima (FWHM) was less than 0.1° indicating good crystallinity. We also observed that film deposited on the carbon crucible had long needles with anisotropic growth very similar to that of pure AlN. Some of the needles grew up to sizes of 200 ,m in length and 40 to 50 ,m in width. It is clear that annealing of SiC-AlN powder or high temperature physical vapor deposition produces similar crystal structure for producing AlN-SiC solid solution. SEM studies indicated that facetted hexagons grew on the top of each other and coarsened and merged to form cm size grains on the substrate. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The Debittering of Navel Orange Juice Using Polymeric FilmsJOURNAL OF FOOD SCIENCE, Issue 4 2007Stéphane C. Fayoux ABSTRACT:, In order to better understand and optimize the sorption of limonin (the major navel orange juice bitter principle) by various plasticized polymeric films, a sorption and plasticizer migration study was carried out using high-performance liquid chromatography (HPLC) and gas chromatography (GC). Low molecular weight (LMW) poly (vinyl chloride) (PVC) plasticized with dioctyl adipate (DOA) gave the best results for both limonin sorption and low DOA migration. Thick films did not significantly sorb more limonin than thin films in the timeframe of our experiments, as the absorption involved rapid surface sorption followed by slow bulk diffusion. The debittering efficiency was a 1000-fold greater than that obtained with current polystyrene divinylbenzene resin beads, with potential for industrial scale debittering. [source] Thermal Softening Behavior and Application to Transparent Thick Films of Poly(benzylsilsesquioxane) Particles Prepared by the Sol,Gel ProcessJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2001Atsunori Matsuda Thick films of poly(benzylsilsesquioxane) (BnSiO3/2) particles, prepared by the sol,gel process, were deposited onto indium-tin-oxide-coated glass substrates by electrophoresis for the application to the micropatterning of the films. BnSiO3/2 particles were thermally softened and sintered at ,50°C, which was above the glass transition temperature of the particles. The films prepared by the electrophoretic sol,gel deposition consisted of aggregates of particles with diameters of 0.2,1 ,m and were opaque. The film shrank from 2.5 ,m to 1.4 ,m in thickness and became transparent upon sintering of the particles during heat treatment at temperatures >100°C. [source] Growth of Hafnium Aluminate Thin Films by Liquid Injection MOCVD Using Alkoxide Precursors,CHEMICAL VAPOR DEPOSITION, Issue 5 2004P.A. Marshall Abstract Thin films of Hf aluminate, (HfO2)x(Al2O3)1,x (Al,=,8.4,38.5,at.-%) have been deposited by liquid injection MOCVD using the metal alkoxide precursors [Hf(mmp)4] (mmp,=,OCMe2CH2OMe) and [Al(OiPr)3]. (HfO2)x(Al2O3)1,x thin films deposited at 500,°C had a thickness range of 7,13,nm and were high purity, with no carbon detected by Auger electron spectroscopy (AES) at the estimated detection limit of 0.5,at.-%. Thick films of (HfO2)x(Al2O3)1,x containing more than ,7,at.-% Al were found by X-ray diffraction (XRD) to be amorphous. High frequency capacitance,voltage (C,V) measurements indicate strong electron trapping and a high density of interface states. [source] Fabrication of Microcantilever Sensors Actuated by Piezoelectric Pb(Zr0.52Ti0.48)O3 Thick Films and Determination of Their Electromechanical Characteristics,ADVANCED FUNCTIONAL MATERIALS, Issue 12 2005H. Park Abstract The integration and the device realization of Pb(Zr,,Ti)O3 (PZT) thick films on Si substrates are known to be extremely difficult because the processing temperature of the PZT thick film is close to the melting point of Si. However, PZT thick-film devices on Si warrant attention as they are appropriate for biological transducers; they generate large actuating forces and have a relatively high sensitivity for mass detection, especially in liquids. In this study, Pb(Zr0.52Ti0.48)O3 thick-film cantilever devices are successfully fabricated on a Pt/TiO2/SiNx/Si substrate using a screen-printing method and microelectromechanical systems (MEMS) process. Elastic and electromechanical properties such as the Young's modulus and transverse piezoelectric coefficient are determined from microstructural and electrical analyses for further mechanical study. The calculated Young's modulus of the thick film, 53.9,±,3.85,GPa, corresponds to the resonant frequency obtained from the measured harmonic oscillation response. The transverse piezoelectric constant, d31, of ,20.7 to ,18.8,pC,N,1 is comparable to that of a dense thin film. These values promise the possibility of determining the resonance properties of a thick-film cantilever by designing its structure and then simulating the harmonic oscillation response. Using the PZT thick-film cantilever, a strong harmonic oscillation with a quality (Q) factor of about 23 is demonstrated in water. The observation of strong harmonic oscillation in liquid implies the feasibility of precise real-time recognition of biomolecules using PZT thick-film cantilevers. [source] Management of acute painful crises in sickle cell diseaseINTERNATIONAL JOURNAL OF LABORATORY HEMATOLOGY, Issue 4 2005T. R. KOTILA Summary Pain is a common mode of manifestation of sickle cell disease (SCD) but there is limited information on pain management in this disorder. This study examines the use of opioids and non-opioid analgesia in the management of painful crisis in adult SCD patients; the routine use of antimalarials and antibiotics as adjunct therapy was also examined. A total of 87% of the patients had had a form of analgesics before presentation, 20% of which had parenteral analgesia. Ten per cent had not used any form of medication while another 10% used non-steroidal anti-inflammatory drugs. When asked, 59% of the patients desired oral non-opioid analgesics while 31% were not concerned about the type of analgesic given. Only 8% requested opioids. Hospital admission was not necessary in 65% of the patients; they were observed in the day-care unit and allowed home within 24 h. Sixty per cent did not have a test for malaria; 66% of those who had the test performed were negative, 35% of those whose thick film for malaria was negative had antimalarials prescribed. Only five patients (7%) were febrile at presentation. Thirty-four per cent had antibiotics prescribed, a third of these parenterally. Thirty-nine per cent had no fever but received antibiotics. [source] Monitoring ultrathin film photopolymerization of tetra-alkylepoxyporphyrin by UV-Vis spectroscopyJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2009Kalle Lintinen Abstract Cationic photopolymerization is a convenient in situ polymerization method for organic thin film preparation. In this work, the polymerization mechanisms is applied for highly viscous cross-linking monomers, using tetra-alkylepoxyporphyrin (TAEP) as a case study. By comparing the UV-Vis spectra of the polymerized sample before and after the unreacted monomers have been dissolved, it is possible to estimate the polymerization yield. An IR spectrum of a reference thick film confirms full polymerization. Scanning fluorescence lifetime microscopy and AFM show the uniformity of the polymer. It was shown that photopolymerization is highly dependent on the substrate nature and requires at best case a 10 min illumination at 90 °C. Thermal polymerization of the same sample requires 10 min heating at 150 °C in dark. It was also shown that TAEP works as a self-sensitizer for cationic photopolymerization. The proposed method is a mild and versatile technique for in situ preparation of thin polymeric films directly from chromophore monomers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6095,6103, 2009 [source] A novel HS-SBSE system coupled with gas chromatography and mass spectrometry for the analysis of organochlorine pesticides in water samplesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 20 2008Paula Grossi Abstract A methodology to analyze organochlorine pesticides (OCPs) in water samples has been accomplished by using headspace stir bar sorptive extraction (HS-SBSE). The bars were in house coated with a thick film of PDMS in order to properly work in the headspace mode. Sampling was done by a novel HS-SBSE system whereas the analysis was performed by capillary GC coupled mass spectrometric detection (HS-SBSE-GC-MS). The extraction optimization, using different experimental parameters has been established by a standard equilibrium time of 120 min at 85°C. A mixture of ACN/toluene as back extraction solvent promoted a good performance to remove the OCPs sorbed in the bar. Reproducibility between 2.1 and 14.8% and linearity between 0.96 and 1.0 were obtained for pesticides spiked in a linear range between 5 and 17 ng/g in water samples during the bar evaluation. [source] Lift-Off PMN,PT Thick Film for High-Frequency Ultrasonic BiomicroscopyJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2010Benpeng Zhu Piezoelectric 0.65Pb(Mg1/3Nb2/3)O3,0.35PbTiO3 (PMN,35PT) thick film with a thickness of approximately 12 ,m has been deposited on the platinum-buffered Si substrate using a sol,gel composite method. The separation of the film from the substrate was achieved using a wet chemical method. The lifted-off PMN,35PT thick film exhibited good dielectric and ferroelectric properties. At 1 kHz, the dielectric constant and the dielectric loss were 3326 and 0.037, respectively, while the remnant polarization was 30.0 ,C/cm2. A high-frequency single-element acoustic transducer fabricated with this film showed a bandwidth at ,6 dB of 63.6% at 110 MHz. [source] Dielectric Properties of Electrophoretically Deposited and Isothermally Pressed BaTiO3 Thick FilmsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2008Ling Zhang Thick BaTiO3 films were prepared on platinum metallic foils by the electrophoretic deposition (EPD) technique using BaTiO3 nanoparticles. In order to increase the density of the thick film, the green film was pressed under an isostatic pressure of 200 MPa before high-temperature sintering. The microstructures of deposited films were examined using X-ray diffraction and scanning electron microscopy techniques. Dielectric properties of the thick films were investigated. As the films grow thicker, the dielectric constant increases gradually and the dielectric loss decreases slightly. The experimental results indicate that isostatic pressing is an effective method to process thick films with dense microstructure and better dielectric properties. [source] Preferred Orientation of Bi4Ti3O12 Thick FilmJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2007Yoshiaki Kinemuchi The preferred orientation of thick films prepared by paste printing is rarely observed because of their bulky polycrystalline nature. We found that a Bi4Ti3O12 thick film with a thickness of ca. 20 ,m showed c -axis-preferred orientation. Initially, the texture of the screen-printed film was found to have a random orientation, which was attributed to the equiaxed particle shape of the raw powder synthesized by the co-precipitation method. During subsequent heating, c -axis orientation emerged in which the degree of orientation was proportional to the film density. Analysis of the orientation distribution revealed that the progress of texturing was attributed to the film deformation, indicating that anisotropic shrinkage and morphological changes in particles during heating influenced the preferred orientation. [source] Temperature dependence of carrier traps in high sensitivity HARP photoconductive filmPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S1 2009Yuji Ohkawa Abstract Amorphous selenium (a-Se) avalanche multiplication photoconductive film, what we call HARP (high-gain avalanche rushing amorphous photoconductor) photoconductive film, has been investigated for the purpose of reporting breaking news at night and producing nature and science programs. The purpose of our work is to develop more sensitive HARP films with high reliability. 15-,m-thick HARP film with an avalanche multiplication factor of about 200 that is thicker and more sensitive than the previous 8-,m-thick one has been studied. However, the thick film has a problem that defects easily occurred during shooting of intense spot lights. The defects are caused by trapped electrons which makes an enhanced internal electric field around the incident light side interface of the film. Defects are suppressed by operating the film at high temperatures, because the thermal energy releases the trapped electrons. This paper describes the relationship between the defect occurrence and the temperature dependence of carries trap in the film. To investigate it, the defect occurrence and dark current characteristics were measured. As a result, it was found that the number of released electrons exceeds that of trapped ones at temperatures over 28.5 °C and that defect occurrence is suppressed by operating the film at over 27.5 °C. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis and Seebeck coefficient of nanostructured phosphorus-alloyed bismuth telluride thick filmsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2008Jian Zhou Abstract Phosphorous-alloyed Bi2Te3 thick films have been prepared by electrochemical deposition. The average grain size of the films was calculated to be 14-26 nm based on Scherrer's equation. The effect of P on the Seebeck coefficient of thermoelectric P-alloyed Bi2Te3 thick film was investigated. The results show that P-alloyed thick film has n-type conductivity with the Seebeck coefficient of -35 ,V/K. The correlation between P site occupancy in the crystal and the Seebeck coefficient was discussed. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Efficiency enhancement of 400 nm violet LEDs utilizing island-like GaN thick film by HVPE technologyPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2007Jenq-Dar Tsay Abstract In this study, we develop a novel way to fabricate InGaN/GaN LED chips with special shape for improving the output power. Crack-free shaped GaN islands were first prepared on c-axis sapphire substrate by using HVPE selective area growth. By doing so, GaN islands with flat top surface and inclined side faces are obtained. Then, the InGaN/GaN LED structure was grown on the top surface of the GaN island subsequently. The output powers of the p-side up and the p-side down shaped LED chip are 1.4 and 2.2 times the output power of the cubic chip, respectively. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Photoluminescence depth-profiling of lattice-mismatched InGaN thick film on GaN using inductively coupled plasma etchingPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2006Ji-Myon Lee Abstract Photoluminescence depth profiling of highly strained In0.1Ga0.9N and In0.15Ga0.85N epitaxial films have been studied employing an inductively coupled Cl2 plasma etching. The photoluminescence measurements showed that thick InGaN films (0.2 ,m) consist of three different structural phases; (i) an InN-rich region near the InGaN film surface, (ii) a region that was free from InN-rich phase under stress-relaxation in the middle of the film, and (iii) an InGaN/GaN interface region. In region (i), a higher wavelength peak from the InN-rich phase was dominant. After removing the surface layer of 500 Å, the PL peaks from InN-rich phases completely disappeared, suggesting that the InN-rich phase region is confined to a depth of 500 Å. In regions of (ii) and (iii), the strain-relaxation between InGaN and GaN had a significant influence on the luminescence properties of InGaN. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Depth profiling of polymer films with grazing-incidence small-angle X-ray scatteringACTA CRYSTALLOGRAPHICA SECTION A, Issue 3 2009Marsha A. Singh A model-free method of reconstructing depth-specific lateral scattering from incident-angle-resolved grazing-incidence small-angle X-ray scattering (GISAXS) data is proposed. The information on the material which is available through variation of the X-ray penetration depth with incident angle is accessed through reference to the reflected branch of the GISAXS process. Reconstruction of the scattering from lateral density fluctuations is achieved by solving the resulting Fredholm integral equation with minimal a priori information about the experimental system. Results from simulated data generated for hypothetical multilayer polymer systems with constant absorption coefficient are used to verify that the method can be applied to cases with large X-ray penetration depths, as typically seen with polymer materials. Experimental tests on a spin-coated thick film of a blend of diblock copolymers demonstrate that the approach is capable of reconstruction of the scattering from a multilayer structure with the identification of lateral scattering profiles as a function of sample depth. [source] Bulk Nanostructured Materials: Non-Mechanical Synthesis,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Yulia Ivanisenko An overview of the synthesis and processing techniques for bulk nanostructured materials that are based on "bottom-up" approaches is presented. Typically, these processes use nanoparticles, which can be produced by a variety of methods in the gas, liquid or solid state, as the basic building blocks. Their assembly into bulk nanostructured materials requires at least one more processing step, such as compaction or the formation of thick films. For certain nanostructures, film deposition techniques can also be employed. A wide range of nanostructures , from thick films with theoretical density to bulk nanocrystalline materials with nanoporosity , exhibiting novel structural and functional properties useful in many fields of applications are presented. Additionally, the properties of these bulk nanostructured materials can be categorized as either tailored, i.e., microstructure-dependent and inherently irreversible, or tunable, i.e., reversible by the application of an external field. Examples of both categories of properties are presented and the special role of the synthesis and processing routes to achieve the necessary nanostructures is emphasized. [source] Controlling Photoactivity in Ultrathin Hematite Films for Solar Water-SplittingADVANCED FUNCTIONAL MATERIALS, Issue 7 2010Florian Le Formal Abstract A promising route to increase the performance of hematite (,-Fe2O3) photoelectrodes for solar hydrogen production through water-splitting is to use an extremely thin layer of this visible light absorber on a nanostructured scaffold. However, the typically poor performance of ultrathin (ca. 20,nm) films of hematite has been the limiting factor in implementing this approach. Here, the surprising effect of a substrate pretreatment using tetraethoxysilicate (TEOS) is reported; it results in drastic improvements in the photoperformance of 12.5,nm thick films of hematite. These films exhibit a water oxidation photocurrent onset potential at 1.1,V versus the reversible hydrogen electrode (vs. RHE) and a plateau current of 0.63,mA cm,2 at 1.5,V vs. RHE under standard illumination conditions, representing the highest reported performance for ultrathin hematite films. In contrast, almost no photoactivity is observed for the photoanode with the same amount of hematite on an untreated substrate. A detailed study of the effects of the TEOS treatment shows that a monolayer of SiOx is formed, which acts to change the hematite nucleation and growth mechanism, increases its crystallinity, reduces the concentration of carrier trapping states of the ultrathin films, and suggests its further application to quantum-dot and extremely-thin-absorber (ETA)-type solar cells. [source] Textured Microstructure and Dielectric Properties Relationship of BaNd2Ti5O14 Thick Films Prepared by Electrophoretic DepositionADVANCED FUNCTIONAL MATERIALS, Issue 7 2009Zhi Fu Abstract An alternative approach to tailor the temperature coefficient of permittivity (TC,r) of high Q dielectric BaO,Re2O3,TiO2 (Re: rare earth elements) thick films is presented. 10- to 80-µm-thick BaNd2Ti5O14 (BNT) films are fabricated by electrophoretic deposition on Pt foils under different processing conditions. Observed anisotropic grain growth is facilitated by constrained sintering. The increase of the sintering temperature increases markedly the aspect ratio of the grains, decreases the dielectric permittivity and TC,r changes from ,114 to +12,ppm °C,1. By controlling the sintering temperature, near-zero TC,r, high Q thick films can be fabricated with 45,<,,r,<,70. These findings are of technological relevance since they demonstrate that control of substrate constraint and sintering conditions can be used to control grain anisotropy and thus microwave properties of the BaO,Re2O3,TiO2. The thick films facilitate scaling to small device sizes for high frequency operation. Similar observations are expected in other microwave systems thus opening further technological opportunities. [source] Fabrication of Microcantilever Sensors Actuated by Piezoelectric Pb(Zr0.52Ti0.48)O3 Thick Films and Determination of Their Electromechanical Characteristics,ADVANCED FUNCTIONAL MATERIALS, Issue 12 2005H. Park Abstract The integration and the device realization of Pb(Zr,,Ti)O3 (PZT) thick films on Si substrates are known to be extremely difficult because the processing temperature of the PZT thick film is close to the melting point of Si. However, PZT thick-film devices on Si warrant attention as they are appropriate for biological transducers; they generate large actuating forces and have a relatively high sensitivity for mass detection, especially in liquids. In this study, Pb(Zr0.52Ti0.48)O3 thick-film cantilever devices are successfully fabricated on a Pt/TiO2/SiNx/Si substrate using a screen-printing method and microelectromechanical systems (MEMS) process. Elastic and electromechanical properties such as the Young's modulus and transverse piezoelectric coefficient are determined from microstructural and electrical analyses for further mechanical study. The calculated Young's modulus of the thick film, 53.9,±,3.85,GPa, corresponds to the resonant frequency obtained from the measured harmonic oscillation response. The transverse piezoelectric constant, d31, of ,20.7 to ,18.8,pC,N,1 is comparable to that of a dense thin film. These values promise the possibility of determining the resonance properties of a thick-film cantilever by designing its structure and then simulating the harmonic oscillation response. Using the PZT thick-film cantilever, a strong harmonic oscillation with a quality (Q) factor of about 23 is demonstrated in water. The observation of strong harmonic oscillation in liquid implies the feasibility of precise real-time recognition of biomolecules using PZT thick-film cantilevers. [source] Feasibility Study of a Thick-Film PZT Resonant Pressure Sensor Made on a PreFired 3D LTCC StructureINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 1 2009Marina Santo Zarnik This paper discusses the feasibility of a piezoelectric resonant pressure sensor made of lead,zirconate,titanate (PZT) thick films on a preprocessed 3D low-temperature co-fired ceramic structure with a deformable diaphragm. Numerical and experimental analyses were carried out. Two different thick-film PZT compositions were characterized. Using experimentally evaluated material properties, a finite-element analysis showed the trends and facilitated the decisions in the design phase of the sensor. [source] Multilayer Construction with Various Ceramic Films for Electronic Devices Fabricated by Aerosol DepositionINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 6 2006Hironori Hatono Aerosol deposition (AD) is applicable as a fabrication technology for microstructures comprising different materials. We used this method for electronic devices that consist of ceramic films and metal electrodes. Various ceramic thick films (5,50 ,m thickness), for example, Al2O3, 2MgO·SiO2, and BaTiO3, were deposited on substrates using room-temperature aerosol deposition. The dielectric constant of BaTiO3 was 78 at 1 MHz. Multilayer constructions with ceramic films and copper electrodes were obtained using aerosol deposition and sputtering. During deposition, photoresist film masks were applied to produce patterns of ceramic films and connections between upper and lower electrodes through the ceramic films. [source] | ||||||||||||||||||||||||||||||||||