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Silica Substrates (silica + substrate)
Kinds of Silica Substrates Selected AbstractsWettability of Silica Substrates by Silver,Copper Based Brazing Alloys inVacuoJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2000Jorge López-Cuevas The sessile drop method has been used to determine the time dependence of the contact angle at 850°C in vacuo for Ag,28 wt% Cu, Ag,35 wt% Cu,1.5 wt% Ti, and Ag,27 wt% Cu,12 wt% In,2 wt% Ti on vitreous and devitrified fused quartz substrates. Nonwetting behavior (, > 90°) was observed for Ag,28 wt% Cu on both substrates with no evident effect of time at temperature. The silica substrate structure, whether crystalline or amorphous, as well as its surface condition, whether smooth or rough, made no significant difference. In contrast, with Ag,35 wt% Cu,1.5 wt% Ti and Ag,27 wt% Cu,12 wt% In,2 wt% Ti the contact angle continuously decreased with time for both silica substrates, and the structure and surface condition of the substrates had a negligible effect in the case of Ag,27 wt% Cu,12 wt% In,2 wt% Ti, which produced essentially the same contact angles on both silica substrates at a given time of hold at 850°C. The contact angles produced by Ag,35 wt% Cu,1.5 wt% Ti on devitrified fused quartz were consistently higher than those produced on the vitreous substrates, with increasing holding time at 850°C. This is attributable to the presence of extensive cracks in the ,-cristobalite layer at the surface of the devitrified substrates, which obstruct wetting and spreading. These results, when correlated with the wettability of preoxidized silicon carbide by the same alloys reported in previous work, could account for the adverse effect on wetting of the high-temperature silica films formed on the surface of the SiC in that work. [source] Chemical, Mechanical, and Antibacterial Properties of Silver Nanocluster,Silica Composite Coatings Obtained by Sputtering,ADVANCED ENGINEERING MATERIALS, Issue 7 2010Monica Ferraris Abstract Silver nanocluster,silica matrix composite coatings have been deposited by radio frequency (RF) co-sputtering on silica substrates. Field emission scanning electron microscopy and X-ray diffraction spectra of the as deposited and heated samples (150,600,°C) revealed the presence of metal silver nanoclusters, their size depending on the heating treatment. The antibacterial activity of the as deposited and heated samples has been measured in accordance to National Committee for Clinical Laboratory Standards, and it has been demonstrated on samples heated up to 450,°C in contact mode and for samples heated at 600,°C in a liquid environment. Their antibacterial activity was still present after gamma ray and ethylene oxide gas (EtO) sterilization of the samples. Silver leaching tests on the as deposited and heated samples has been measured by graphite furnace atomic absorption spectrometer, revealing an amount ranging from 0.1 to 0.9,µg mm,2, over 28 days. Tape resistance (ASTM D3359-97) and scratch resistance tests have been done on each sample revealing a good adhesion of the coatings on silica. [source] Biomimetic Surfaces for High-Performance OpticsADVANCED MATERIALS, Issue 46 2009Yunfeng Li High-performance antireflective and antifogging surfaces are fabricated on planar silica substrates and planconvex lenses. Such surfaces dramatically suppress reflection over a large range of wavelengths and a large field of view. Additionally, the ARS surfaces exhibit high-quality superhydrophilic properties. For antireflective and antifogging applications, the ARS surfaces exhibit more high-quality mechanical stability and better durability than multilayered films. [source] Wettability of Silica Substrates by Silver,Copper Based Brazing Alloys inVacuoJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2000Jorge López-Cuevas The sessile drop method has been used to determine the time dependence of the contact angle at 850°C in vacuo for Ag,28 wt% Cu, Ag,35 wt% Cu,1.5 wt% Ti, and Ag,27 wt% Cu,12 wt% In,2 wt% Ti on vitreous and devitrified fused quartz substrates. Nonwetting behavior (, > 90°) was observed for Ag,28 wt% Cu on both substrates with no evident effect of time at temperature. The silica substrate structure, whether crystalline or amorphous, as well as its surface condition, whether smooth or rough, made no significant difference. In contrast, with Ag,35 wt% Cu,1.5 wt% Ti and Ag,27 wt% Cu,12 wt% In,2 wt% Ti the contact angle continuously decreased with time for both silica substrates, and the structure and surface condition of the substrates had a negligible effect in the case of Ag,27 wt% Cu,12 wt% In,2 wt% Ti, which produced essentially the same contact angles on both silica substrates at a given time of hold at 850°C. The contact angles produced by Ag,35 wt% Cu,1.5 wt% Ti on devitrified fused quartz were consistently higher than those produced on the vitreous substrates, with increasing holding time at 850°C. This is attributable to the presence of extensive cracks in the ,-cristobalite layer at the surface of the devitrified substrates, which obstruct wetting and spreading. These results, when correlated with the wettability of preoxidized silicon carbide by the same alloys reported in previous work, could account for the adverse effect on wetting of the high-temperature silica films formed on the surface of the SiC in that work. [source] Towards optical-quality nanocrystalline diamond with reduced non-diamond contentPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 9 2009Z. Remes Abstract Our nominally undoped nanocrystalline diamond (NCD) films were deposited on fused silica substrates by the microwave plasma enhanced chemical vapor deposition (MW CVD) at a relatively low temperature below 600,°C. They show high dark resistivity and measurable photosensitivity after surface oxidation. We present the "true" optical absorptance spectra calculated from transmittance T and reflectance R measurements corrected on the surface scattering and compare them with the normalized photocurrent spectra. The optical scattering does not allow to evaluate the small optical absorption in visible and near IR range from the T and R spectra. The photocurrent spectra were measured in the ultraviolet, visible, and near infrared optical range using the dual beam photocurrent spectroscopy (DBP) under constant UV illumination. Previously, NCD films often showed non-diamond content with the photo-ionization threshold at 0.8,eV increasing significantly the optical absorption in near IR and visible region. Here, we show that the non-diamond content can be reduced by several orders of magnitude by depositing NCD on the carefully selected UV-grade fused silica substrates under the optimized growth conditions followed by the post-deposition chemical etching and cleaning. Unlike the NCD layers with high non-diamond content, the NCD layers with reduced non-diamond content are stable up to 450,°C. [source] Optical properties of TiO2 thin films prepared by chemical spray pyrolysis from aqueous solutionsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3-4 2010R. Ayouchi Abstract Titanium dioxide (TiO2) is known to have three different kinds of polymorphous crystalline forms: rutile, anatase, and brookite. The rutile phase is always formed at higher temperatures, while the anatase phase is formed at lower temperatures and transformed into rutile phase above 800 ºC. Various deposition techniques have been developed for depositing TiO2 thin films, including evaporation, sputtering, chemical vapour deposition and thermal oxidation of titanium. Among them, the Chemical Spray Pyrolysis (CSP) technique has many advantages, such as good conformal coverage, the possibility of epitaxial growth and the application to large area deposition. Also, this method is low cost and it is easy to control the deposition growth parameters. In the present work, TiO2 thin films have been deposited on p-Si (001) and fused silica substrates by Chemical Spray Pyrolysis (CSP) method from aqueous solution containing titanium (IV) isopropoxide (Ti[OCH(CH3)2]4. As-deposited thin films show anatase polycrystalline structure, and rutile phase formed for films annealed at 750ºC. SEM images have confirmed a smooth and crack-free surface with low surface roughness. X-ray photoelectron spectroscopy (XPS) combined with 4 keV Ar+ depth profiling has shown that crystallized films correspond to TiO2. Residual carbon coming from the organic precursor solution is only detected at the surface of the film. Thin films deposited on fused silica were highly transparent (more than 85%), with an indirect optical band gap of 3,43 and 3,33 eV for as-deposited and annealed films, respectively, and refractive indexes in the range between 2.01,2.29. Spectroscopic Ellipsometry (SE) also has been used to extract optical parameters. SE data fitted to triple-layer physical model revealed the same tendency to increase refractive index in annealed films. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Photoluminescence properties of erbium-doped amorphous gallium-germanium-selenium films fabricated by RF sputteringPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S1 2009Takahiko Imai Abstract Chalcogenide glasses have various useful features for optical devices such as a high refractive index, low-loss transmission in the mid-IR, and low phonon energies. The fabrication of thin films is important for use in waveguide applications and integrated photonics. In this work, we report the properties of vacuum deposited films of gallium-germanium-selenium glasses onto fused silica substrates by an RF magnetron sputtering technique (RF electric power of 40-250 W and growth rate of 0.01-2.1 ,m/min). The concentration of Er3+ ions is controlled by the number of sintered Er2S3 small plates on a target. Samples are shown to be in an amorphous-like state as measured by X-ray diffraction experiments. Film thicknesses are proportional to the RF sputtering power and sputtering time. The compositions of films obtained from energy dispersive X-ray (EDX) analysis. There are much dependent on the condition of the sputtering target, for example whether the target is in the bulk or powder-state. Photoluminescence (PL) spectrum, intensity, and lifetime at 1550 nm band are measured by excitation from a 973 nm laser. The PL band of the films has a similar shape to those of bulk glasses. The PL intensity increased with the RF electric power. The PL lifetime at the 1550 nm band of the film is about 1.8-2.6 ms; the latter values are similar to those of bulk samples. The results show that the RF sputtering is a potential method of fabrication for Er-doped GeGaSe thin films. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||