Alumina Substrates (alumina + substrate)

Distribution by Scientific Domains
Distribution within Polymers and Materials Science


Selected Abstracts


Flow-Through-Type DNA Array Based on Ideally Ordered Anodic Porous Alumina Substrate ,

ADVANCED MATERIALS, Issue 23-24 2004
F. Matsumoto
A flow-through-type DNA array fabricated from an ideally ordered anodic porous alumina substrate is reported. Single-stranded probe DNA was affixed to the walls of the sub-micrometer-diameter holes, and fluorescently labelled target DNA was passed through the holes in the substrate. Fluorescence microscopy revealed an ordered array of fluorescent spots after the hybridization (see Figure), demonstrating the applicability of these porous alumina substrates to fabrication of high-density DNA arrays. [source]


Ionic Conductivity Enhancement of La2Mo2,xWxO9 Nanocrystalline Films Deposited on Alumina Substrates by the Sol,Gel Method

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2009
Zhong Zhuang
Dense, crack-free, and uniform La2Mo2,xWxO9 (x=0, 0.1, and 0.2) nanocrystalline films were successfully synthesized on poly-alumina substrates via a modified sol,gel method, with inorganic salt of La(NO3)36H2O, (NH4)6Mo7O244H2O, and (NH4)6H2W12O24 as precursors. Pure La2Mo2O9 phase was confirmed by X-ray diffractometer when the annealing temperature was >500C. The average grain size of the La2Mo2,xWxO9 films is in the range of 90,400 nm, depending upon the conditions of thermal treatment, and the thickness of films can reach 1 ,m by repetitive spin-coating. The electrical conductivity increases with decreasing grain size and reaches 0.074 S/cm at 600C in the film with a grain size of 90 nm, which is one order of magnitude higher than that in the corresponding bulk materials. W-doping can suppress the phase transition that occurs at 580C in pure La2Mo2O9 and enhance the low-temperature ionic conductivity. Furthermore, the activation energy of conductivity in the nanocrystalline La2Mo2O9 films decreases to about 0.6 eV in comparison with 1.0 eV in the bulk ones, which implies that the grain resistance prevails in the total resistance, when grain size reduces to nanometer domain. [source]


Cell Proliferation of Human Fibroblasts on Alumina and Hydroxyapatite-Based Ceramics with Different Surface Treatments,

INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 2 2010
Juliana Marchi
Biocompatibility is an important characteristic of dental implant material, and in vitro tests are required to elucidate the interaction between these materials and human tissues. Cell proliferation assays were done with fibroblasts plated on the surface of alumina and hydroxyapatite sintered samples, each with a different surface treatment (sintered, rectified, or polished). After 1, 2, and three days, the samples were prepared for scanning electron microscopy observations. The data were compared by analysis of variance followed by Tukey's test. It was concluded that neither the hydroxyapatite or alumina substrate is cytotoxic, and hydroxyapatite is more biocompatible than alumina. [source]


Flow-Through-Type DNA Array Based on Ideally Ordered Anodic Porous Alumina Substrate ,

ADVANCED MATERIALS, Issue 23-24 2004
F. Matsumoto
A flow-through-type DNA array fabricated from an ideally ordered anodic porous alumina substrate is reported. Single-stranded probe DNA was affixed to the walls of the sub-micrometer-diameter holes, and fluorescently labelled target DNA was passed through the holes in the substrate. Fluorescence microscopy revealed an ordered array of fluorescent spots after the hybridization (see Figure), demonstrating the applicability of these porous alumina substrates to fabrication of high-density DNA arrays. [source]


MgTiO3 and Ba0.60Sr0.40Mg0.15Ti0.85O3 Composite Thin Films with Promising Dielectric Properties for Tunable Applications

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2008
Lina Gao
Mg2TiO4 -doped Ba0.60Sr0.40Mg0.15Ti0.85O3 (BSTM) thin films with different Mg2TiO4 concentrations were deposited on a polycrystalline alumina substrate via the sol,gel method. With the addition of Mg2TiO4, MgTiO3, MgAl2O4, and BSTM phases were formed in these composite thin films. The dielectric loss of the composite thin films decreased about one order of magnitude and the tunability still remained above 15% at a DC-applied electric field of 80 kV/cm. The dielectric constant decreased from 1040 to 388. The low dielectric constant, high tunability, and figure of merit of these composite thin films can be useful for potential tunable devices. [source]


Self-heterodyne diode mixer with GCPW using thin film process at 60 GHz

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 1 2009
Seung-Woon Choi
Abstract A self-heterodyne diode mixer is proposed using thin film process based on alumina substrate at 60 GHz in conjunction with grounded coplanar waveguide transition. To down-convert both very low RF and LO signals received simultaneously from transmitter for self-heterodyne communication scheme, the proposed mixer adapted with the knee voltage bias condition of 0.65 [V] improves its mixing efficiency significantly. The designed SHM shows the conversion loss of ,15.13 dB at RF and LO frequencies of 60.565 and 59.01 GHz, respectively, with both input powers of ,15 dBm and it also can defines IMD free input dynamic range as ,30 dBm. The measured return losses satisfies with more than 20 dB and 9 dB for RF/LO input and IF output port, respectively. 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 13,15, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23959 [source]


YIG thin films for magneto-optical and microwave applications

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2004
T. Boudiar
Abstract Thin films of Yttrium Iron Garnet (YIG) are grown by radio frequency magnetron non reactive sputtering system on quartz and Gadolinium Gallium Garnet (GGG) for optical applications or alumina substrates for microwave applications. A post deposition annealing is needed to obtain the crystallization of YIG films and the magnetic properties which are correlated with the magneto-optical properties. Their crystallographic, morphologic and magnetic properties are explored. The variation of Faraday rotation is studied versus the wavelength. For both optical substrates, quartz and GGG, results are comparable with the literature for bulk material. A microwave isolator was realized with YIG thin film on alumina substrate in a coplanar configuration. ( 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Flow-Through-Type DNA Array Based on Ideally Ordered Anodic Porous Alumina Substrate ,

ADVANCED MATERIALS, Issue 23-24 2004
F. Matsumoto
A flow-through-type DNA array fabricated from an ideally ordered anodic porous alumina substrate is reported. Single-stranded probe DNA was affixed to the walls of the sub-micrometer-diameter holes, and fluorescently labelled target DNA was passed through the holes in the substrate. Fluorescence microscopy revealed an ordered array of fluorescent spots after the hybridization (see Figure), demonstrating the applicability of these porous alumina substrates to fabrication of high-density DNA arrays. [source]


Smooth Continuous Films of Stoichiometric Silicon Carbide from Poly(methylsilyne),

ADVANCED MATERIALS, Issue 8 2004
W. Pitcher
A new synthesis of the silicon-network-backbone polymer poly(methylsilyne) gives a material that is easily converted by pyrolysis to smooth continous films of stoichiometric silicon carbide (see Figure). The films are adherent to the silicon or alumina substrates, and show root mean square roughness of 169, over a 500,,m range. Applications in electronics are envisaged. [source]


Constrained Sintering of a Glass Ceramic Composite: II.

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2009
Symmetric Laminate
The sintering behavior of symmetric laminates has been experimentally measured and modeled. Two cases are distinguished: (i) sintering of a viscous layer between viscous substrates and (ii) sintering of a viscous layer between elastic substrates. A simple model based on a persisting isotropic microstructure allowed computation of developing in-plane stresses. These in conjunction with a viscous Poisson's coefficient were taken to predict out-of-plane stresses and finally densification rate. This approach, however, proved unsuccessful to predict the large observed differences in densification rate between laminates constrained by either green or dense alumina substrates. The discrepancy was found to be due to widely different microstructures developing with different degrees of elastic constraint. Pore area and pore and particle orientation were determined to quantify these microstructural changes. [source]


Preparation of Highly Dense PZN,PZT Thick Films by the Aerosol Deposition Method Using Excess-PbO Powder

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2007
Jong-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 700C, and the films deposited on sapphire were annealed at 900C 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 900C 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]


Design of Ceramic Materials for Chemical Sensors: Effect of SmFeO3 Processing on Surface and Electrical Properties

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2001
Hiromichi Aono
Perovskite-type SmFeO3 powders were prepared by the thermal decomposition of a heteronuclear complex, Sm(Fe(CN)6)4H2O and by solid-state reaction between the corresponding single oxides, Sm2O3 and Fe2O3. The thermal decomposition behavior of the complex was studied by thermogravimetric analysis. X-ray diffractometry was used to investigate the structure of the products from the complex thermal decomposition and the formation of SmFeO3 from the oxide mixture. Powders prepared by both methods were used to deposit thick films onto alumina substrates with comb-type gold electrodes. The microstructure and chemical homogeneity of the film surfaces were investigated by scanning electron microscopy and Auger electron spectroscopy. Thick SmFeO3 single-phase films having a homogeneous elemental distribution on the surface were obtained when powder prepared by thermal decomposition of the complex was used for deposition, even when the powder was fired at low temperature (800C). Surface chemical analysis was performed by X-ray photoelectron spectroscopy (XPS). The O 1s XPS line was deconvoluted into two peaks, attributed to adsorbed oxygen (Oad) and oxygen in the lattice (Olattice). Quantitative analysis showed that the surface coverage of iron, expressed as Fe/(Fe + Sm), was larger for the films prepared using the solid-state reacted powder. Although the Olattice/(Fe + Sm) atomic ratio was not influenced by the processing procedures (and, thus, by iron surface coverage), the amount of Oad decreased with increasing iron surface coverage. A model of the SmFeO3 surface was used to determine that the outermost layer of the perovskite-type SmFeO3 prepared from the complex consisted mainly of samarium ions that could each bond four adsorbed oxygen ions. A single oxygen ion could adsorb onto an iron ion, and therefore, the content of adsorbed oxygen was lower for the film prepared from the solid-state reacted powders, which showed larger iron surface coverage. Electrical conductance measurements, performed with increasing temperature in different gaseous environments, confirmed these findings. Higher conductances and lower activation energies were observed for the films with larger samarium surface coverage. [source]


YIG thin films for magneto-optical and microwave applications

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2004
T. Boudiar
Abstract Thin films of Yttrium Iron Garnet (YIG) are grown by radio frequency magnetron non reactive sputtering system on quartz and Gadolinium Gallium Garnet (GGG) for optical applications or alumina substrates for microwave applications. A post deposition annealing is needed to obtain the crystallization of YIG films and the magnetic properties which are correlated with the magneto-optical properties. Their crystallographic, morphologic and magnetic properties are explored. The variation of Faraday rotation is studied versus the wavelength. For both optical substrates, quartz and GGG, results are comparable with the literature for bulk material. A microwave isolator was realized with YIG thin film on alumina substrate in a coplanar configuration. ( 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


8% Efficient thin-film polycrystalline-silicon solar cells based on aluminum- induced crystallization and thermal CVD

PROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 7 2007
I. Gordon
Abstract A considerable cost reduction could be achieved in photovoltaics if efficient solar cells could be made from polycrystalline-silicon (pc-Si) thin films on inexpensive substrates. We recently showed promising solar cell results using pc-Si layers obtained by aluminum-induced crystallization (AIC) of amorphous silicon in combination with thermal chemical vapor deposition (CVD). To obtain highly efficient pc-Si solar cells, however, the material quality has to be optimized and cell processes different from those applied for standard bulk-Si solar cells have to be developed. In this work, we present the different process steps that we recently developed to enhance the efficiency of pc-Si solar cells on alumina substrates made by AIC in combination with thermal CVD. Our present pc-Si solar cell process yields cells in substrate configuration with efficiencies so far of up to 80%. Spin-on oxides are used to smoothen the alumina substrate surface to enhance the electronic quality of the absorber layers. The cells have heterojunction emitters consisting of thin a-Si layers that yield much higher Voc values than classical diffused emitters. Base and emitter contacts are on top of the cell in interdigitated finger patterns, leading to fill factors above 70%. The front surface of the cells is plasma textured to increase the current density. Our present pc-Si solar cell efficiency of 8% together with the fast progression that we have made over the last few years indicate the large potential of pc-Si solar cells based on the AIC seed layer approach. Copyright 2007 John Wiley & Sons, Ltd. [source]


Kinetics and Film Properties of Boron Nitride Derived from Trimethoxyborane/Ammonia by Chemical Vapor Deposition,

CHEMICAL VAPOR DEPOSITION, Issue 6 2004
H. Strakov
Abstract The kinetics of the CVD of boron nitride from trimethoxyborane (TMOB) and ammonia (NH3) under atmospheric pressure was investigated by varying the following process parameters: temperature, residence time of the reactants, molar fraction of TMOB, and the NH3/TMOB ratio, ,. A kinetic power law equation was derived, that describes the experimental results with good accuracy. The reaction order with respect to TMOB is found to be 0.9 and ,,0.2 with respect to NH3. Between 800,C and 950,C, the deposition rate is controlled by the surface reaction kinetics with apparent activation energy of 115.1,kJ,mol,1. The deposited BN films were characterized by IR spectroscopy, Raman spectroscopy, and X-ray diffraction (XRD). The microstructure of the deposits depends on the nature of the substrates used. Turbostratic boron nitride (t-BN) was deposited on graphite, and hexagonal boron nitride (h-BN) on alumina substrates. X-ray photoelectron spectroscopy (XPS) analyses show nearly stoichiometric BN films for deposition temperatures in the range 850,950,C for high amounts of ammonia (100,<,,,<,150) in the feed gas. [source]