bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thin Anisotropic Coatings Based on Sol-Gel Technology.
Authors: Randall Holmes-Farley S. , Yanyo Lynn C. 
Published: March 2011

ABSTRACTUsing sol-gel technology, thin organic/ceramic (ceramer) coatings have been applied to metal surfaces in order to enhance such surface properties as adhesion promotion and corrosion prevention. Isotropic coatings have been found to be effective in certain applications such as corrosion prevention, but the formation of anisotropic coatings permits greater flexibility over the resulting properties. Isotropic coatings derived from tetraethoxysilane, for example, effectively inhibit corrosion while being only 100 to 1000 Å thick. These coatings do not, however, promote adhesion. Thin coatings made from traditional silane adhesion promoters alone are unable to prevent corrosion of metallic substrates.Using monomers with appropriate reactivities permits the single-step synthesis of anisotropic coatings that can both promote adhesion and prevent corrosion. These types of anisotropic coatings allow the physical and chemical properties of a coating to be varied as a function of distance from the substrate and confer properties to the substrate that would not be possible from a single isotropic coating. The principle behind the construction of these anisotropic coatings is general enough that it can be used in many applications where microengineering of surface structures is important.
Ceramic Fiber Coating by a Non-Aqueous Sol-Gel Process
Authors: Montgomery F. C. , Streckert H. H. , Harrington R. O. , Kaae J. L. , Paguio S. P. , Wall D. R. 
Published: March 2011

ABSTRACTThin coatings of Al2O3, and Y2O3, have been prepared on desized Nicalon yarn. The layers were deposited by dip coating in homogeneous, alcohol solutions of partially hydrolyzed metal alkoxides. The coating thicknesses could be controlled by multiple dipping.The uniformity of the coatings was affected by the alkoxide concentration. Solutions containing greater than 1 wt % equivalent oxide resulted in oxide bridging the void between the fibers.Transmission Electron Microscopy (TEM) studies on alumina coatings formed by dip coating 300 mesh nickel grids, have shown that either eta or gamma alumina is formed after heating at temperatures as low as 700 °C. The rate of grain growth increases as the temperature increases. In addition, increased grain growth is observed for films produced from solutions with higher water:metal ratios.The strength of coated fibers heat treated in air after coating has been determined. Alumina, and yttria coatings reduce the strength of the fiber after heating at temperatures above 900 °C. Scanning Auger analysis suggests that the coating is reacting with the fiber at these high temperatures.
Improvement of Building Materials Performance by Sol-Gel Derived Coatings
Authors: Beier Wolfram , Odler Ivan 
Published: March 2011

ABSTRACTDifferent multicomponent solutions have been developed by which building materials were coated. After drying and annealing, the coatings convert into silicate based glassy films. TEOS or fumed silica were used as silica carriers and by adding lead compounds also low melting compositions were prepared. In some cases it proved to be convenient to adjust the viscosity of the solutions by additions of suitable organic polymers. The heat treatment was done either in an electric furnace or by means of a special acetylene burner. The produced films can protect building materials against corrosion, may reduce the absorption and permeation of water or improve abrasion resistance.
Effect of Precursors on Lithium Infiltrated Silica Gels Studied by Xps
Authors: Ho S.F. , Klein L. C. 
Published: March 2011

ABSTRACTLithium silicate gels of composition 15 mole % lithia - 85 mole % silica were prepared by soaking highly porous silica gels in aqueous LiNO3 or methanolic LiOH solutions. The fracture surfaces of these samples were studied by X-ray photoelectron spectroscopy (XPS). High resolution XPS core level spectra were collected such that both chemical shift and atomic concentration could be determined. While the average lithium content was slightly higher in LiNO3 gels, only some of the lithium was associated with the silica network. In contrast, most of the lithium in LiOH gels was associated with the network.
Sol-Gel Film Formation by Dip Coating
Authors: Hurd Alan J. , Jeffrey Brinker C. 
Published: March 2011

ABSTRACTThe physical aspects of sol-gel film formation are discussed, including the steady state film profile during dip coating, evaporation, and capillary phenomena. It is argued that, since the evaporation rate increases singularly near a sharp boundary (analogous to an electric field singularity near a sharp conductor), the film profile near the drying line falls off precipitously, following the inverse form of the evaporation singularity. Finally, the large tensile pressures in the solvent during the final stage of drying of a porous film are discussed from the point of view of controlling the degree of capillary collapse.
Oxometalate-Glass Composites and Thin Films
Authors: Moller Karin , Bein Thomas , Jeffrey Brinker C. 
Published: March 2011

ABSTRACTNew glass-composites with ion exchange properties have been developed. Ammonium 12-molybdophosphate (AMP) (NH4)3PMo12O40, and ammonium 12-tungstophosphate (AWP) (NH4)3PW12O40, known for their ion exchange capabilities, are included either in preformed aerogels with defined pore size, or are added to sol-gel mixtures during the process of gel formation. Characterization is carried out by FTIR, Raman and EXAFS spectroscopy. Ion exchange capacities for the oxometalate precursors are determined for silver and rubidium and are compared to those of the glass composites. Glass composites show high ion exchange capacity, but some portion of the metalate complexes leaches from the glass during the procedure. This is in contrast to thin composite films, which have almost no porosity and do not show loss of metalate. EXAFS spectroscopy demostrates that the oxometalate microstructure is maintained in glass composites and that rubidium ions after ion exchange in glasses occupy similar cation positions as in the precursor compounds.
Biomimetic Processing of Ceramics and Ceramic-Metal Composites
Authors: Yasrebi M. , Kim G. H. , Gunnison K. E. , Milius D. L. , Sarikaya M. , Aksay I. A. 
Published: March 2011

ABSTRACTBiomimetic design and processing of laminated B4C-Al cermets, based on knowledge gained from the microstructure-property characterization of abalone shells, is described. In the nacre section of the shell, the microstructure is highly organized as CaCO3(aragonite) crystals, with a thickness of 0.25 μm, separated by a layer of organic matter 300–500 Å thick. This organization forms a miniature “brick and mortar” microstructure. The resultant strength and fracture toughness of the nacre, i.e., 180 MPa and 7 MPa-m1/2, are many orders of magnitude higher than those of monolithic CaCO3. The processing of laminated B4C-Al cermets, based on the microstructure of the nacre, was performed by a combination of tape casting of the ceramic and infiltration of the metal. The resultant cermets displayed a 40% increase in both fracture toughness and strength over monolithic B4C-Al cermets.
Intercalation Chemistry: a Novel Approach To Materials Design
Authors: Giannelis E.P. , Mehrotra V. , Russell M.W. 
Published: March 2011

ABSTRACTIntercalation of layered solids is used as a means to manipulate a variety of molecular and polymeric species into well-ordered multilayer films with an architecture controllable at the molecular level. Dielectric, conductivity and optical measurements demonstrate the potential of developing new families of materials with new functionalities by exploiting the synergistic effect of guest/host interactions.
Ion-Implantation Effects on Spin-on-Glass (Sol-Gel) SiO2 Films
Authors: Shacham-Diamand Y. , Moriya N. , Kalish R. 
Published: March 2011

ABSTRACTSilicon and phosphorus ions were implanted into Spin-On-Glass (Sol-Gel) SiO2 films and were found to modify the material properties. Two SOG types, polysiloxane andsilicate, were ion-implanted with doses in the 5 × 1014 − 1.65 × 1016cm−2range and energies of 40keV - 190keV. The implanted SOG on silicon samples were characterized by ellipsometry, infra-red spectroscopy, etching and capacitance measurement of aluminum/SOG/silicon devices. The results indicate that the polysiloxane type SOG shrinks due to the implant and its effective refractive index increases. The ion-implant of the polysiloxane SOG also changed its structure and composition as seen by the variations of the infra-red transmission spectrum, etching characteristics, and dielectric constant. Silicate SOG exhibits less shrinkage due to the implant but its other characteristics show dependence on the dose similar to that of the polysiloxane SOG.
Tailored Molecular Precursors of Yttrium Oxide Using Functional Alcohols and Acetylacetone as Modifiers
Authors: Hubert-Pfalzgraf Liliane G. , Poncelet Olivier , Daran Jean-Claude 
Published: March 2011

ABSTRACTYttrium is involved as oxide in a variety of advanced materials. Hydrolysis of its most common alkoxide, yttrium oxoisopropoxide Y5O(OiPr)13 , is difficult to control as a result of the high electropositivity of the metal. Functional alcohols such as 2-methoxyethanol and acetylacetone have thus been used as modifiers. These tailored precursors have been fully characterized (single crystal X-Ray diffraction, IR, NMR. ). The tendency of methoxyethanol to act as a bridging ligand and to stabilize high oligomers - Y(OC2H4OMe)3 is a decamer - gives some insight into its behavior as “network builder”. The unexpected cleavage of acetylacetone offers a route to an interesting acetatoacetylacetonate derivative, Y2(OAc)2(acac)4(H2O)2 , but also suggest that this classical “modifier” could be affected by the hydrolysis-polycondensation reactions of the metallic species during the sol-gel process. Comparison of the hydrolysis behavior of the different precursors was performed.
Synthesis and Structural Characteristics of Polycerams
Authors: Boulton J.M. , Fox H.H. , Neilson G.F. , Uhlmann D.R. 
Published: March 2011

ABSTRACTSol-gel techniques are readily applicable to the preparation of Polycerams. These hybrid materials uniquely combine organic and inorganic functionalities at the molecular level. Polycerams have here been prepared from tetraethoxysilane and modified, functionalized polybutadiene, polyethylene oxide urethane and polyethyleneimine. The structures and physical characteristics of the materials are here in reported.
Mixed Carbides via Polymer Route
Authors: Soraru Gian D. , Babonneau Florence , Mackenzie John D. 
Published: March 2011

ABSTRACTSeveral polymetallocarbosilanes, pre-ceramics precursors for Si-M-C-O systems, have been prepared from polycarbosilane and metallic alkoxides, M(OR)n with M = Ti, Zr and Al. Polymers have essentially been characterized by Magic Angle Spinning Nuclear Magnetic Resonance (MAS-NMR). The pyrolysis process has been followed for each system with X-Ray Diffraction (XRD) and MAS-NMR. The role of the metallic element M on the transformation process of these systems will be discussed.
Fabrication of Superconducting Bi-Sr-Ca-Cu-O Oxide Films Using the Metal Alkoxide Method
Authors: Katayama Shingo , Sekine Masahiro 
Published: March 2011

ABSTRACTSuperconducting films in the Bi-Sr-Ca-Cu-O system were fabricated using metal alkoxides. To make a mixed alkoxide solution into a dip-coating solution, insoluble Cu alkoxide was modified with 2-dimethylaminoethanol and insoluble Bi alkoxide was dissolved in the presence of Ca and/or Sr alkoxides. The structures of these alkoxide derivatives were studied by FT-IR, 1 H-NMR, and EXAFS. The film with Tc(zero)=115K was fabricated using the alkoxide solution with a nominal composition of Bi:Sr:Ca:Cu=2:2:3:4.
Superconducting Yba2Cu3O7−X Fibers Fabricated by the Sol-Gel Method Using Metal Alkoxides
Authors: Katayama Shingo , Sekine Masahiro 
Published: March 2011

ABSTRACTSuperconducting YBa2Cu3O7−x fibers were fabricated by the sol-gel method using modified metal alkoxides. To prepare precursors of a homogenous and viscous sol, Y and Cu alkoxides were modified with ethyl acetoacetate(EAA) and ethylenediamine(en), respectively. Their structures were determined by FT-IR and EXAFS. The sol prepared from modified alkoxides was spun into gel fibers by the spinning apparatus. They were subsequently fired to obtain superconducting fibers.
Sol-Gel Processing of the Ti2Ca1Ba2Cu2O8+X High Tc Superconducting Phase
Authors: Teepe M. R. , Kenzer D. S. , Moore G. A. , Kordas G. 
Published: March 2011

ABSTRACTAn alkoxide Sol-Gel system was developed to produce bulk powders of the TI2Ca1Ba2Cu2O8+x high Tc superconducting phase. Methoxyethoxide and Cu(II) ethoxide precursors were used for the formation of homogeneous sols. Solubility of the Cu(II) ethoxide was aided by using a 2-methoxyethanol/methyl ethyl ketone/toluene solvent system. The sols were characterized by small angle x-ray scattering (SAXS) and TEM. Powders were produced by rotary evaporation followed by thermal treatment in a closed container with thallium metal present at 900°C for various calcination times. Powders were characterized by x-ray diffraction, resistivity and magnetic susceptibility measurements, and chemical analysis. Samples exhibited transition onsets between 100 and 110K depending upon the processing conditions.
Preparation of Superconducting YBa2Cu3O7−x Compounds By Water Extraction Variant Of Sol-Gel Process
Authors: Deptula A. , Lada W. , Olczak T. , zoltowski T. , Di Bartolomeo A. 
Published: March 2011

ABSTRACTThe starting sols were prepared by addition of ammonium hydroxide to acidic solutions of Y-Ba-Cu acetates or by dissolving solid Ba9CO9 or CuCO9.CuCOH)2H2O in acetates of the remaining components. The sols were then gelled to spherical particles with diameter below 50μm by extracting water with 2-ethyl-l-hexanol or to shard by evaporation of water. After thermal treatment of both powders amorphous and then crystalline YBa2Cu,9O7−x were obtained. Formation of these compounds is strongly improved by aging the gel at 200°C. Green and sintered pellets exhibit excellent superconductivity properties.
Preparation, Thermal Processing Behavior And Characterization Of Powdered And Bulk Yba2Cu3O7−x From Freeze Dried Nitrate Solutions.
Authors: Coppa N. , Bura A. , Schwegler J. W. , Salomon R. E. , Myer G. H. , Crow J. E. 
Published: March 2011

ABSTRACTSolutions of Y, Ba and Cu nitrate were spray-frozen. Very small particles consisting of atomic mixtures of these salts remained after the water was sublimed. These YBCO precursors were characterized and their behavior was studied in detail while they were thermally decomposed by a variety of techniques. Kilogram size batches are routine. The final YBCO products were obtained as powders and sintered bars. Sintered materials exhibited excellent phase purity (>99%) and super-conducting characteristics (Tc = 92 K), while powdered materials had secondary phases present. Some of these samples having high percentages of second phases exhibited sudden drops in resistivity to a few micro-ohms at 200 or 240 K followed by a zero resistance transition at 92 K. Coincident with this drop in resistance was a discontinuity in the magnetization.
Aryl-Bridged Polysilsesquioxanes - New Microporous Materials.
Authors: Shea Kenneth J. , Webster Owen , Loy Douglas A. 
Published: March 2011

ABSTRACTThe first representatives of a new family of microporous, aryl-bridged polysilsesquioxanes have been prepared by sol-gel processing of bis-1,4-(triethoxysilyl)benzene la, bis-4,4′- (triethoxysilyl)biphenyl 2a, bis-4,4′-(triethoxysilyl)terphenyl 3a, and bis-9,10-triethoxysilyl anthracene 4a. The bis(trichlorosilyl) analogs of la and 2a (lb and 2b, respectively) were also examined. The materials produced by hydrolysis and condensation of the monomers provide an opportunity to fully condense to a network with rigid-rod organic spacers interspaced at regular intervals in the silicate-like framework. The xerogels produced upon subsesquent processing of the gels have extremely high surface areas (256–1100 m2/g; BET) with porosities confined to the micropore domain (< 200 nm). Solid state (CP MAS) 13C and 29Si NMR were used to evaluate the extent of hydrolysis and degree of condensation in the xerogels. The porosity and thermal stability of the aryl bridged polysilsesquioxanes may lead to applications as chromatographic absorbents. The transparent materials may also have optical applications arising from both the gels′ high refractive indices and the covalent incorporation of ultraviolet chromophores.
Non-Linear Organic Dyes In Polyceram Hosts
Authors: Boulton J.M. , Thompson J. , Fox H.H. , Gorodisher I. , Teowee G. , Calvert P.D. , Uhlmann D.R. 
Published: March 2011

ABSTRACTNon-linear organic dyes, such as 2-methy1–4-nitroaniline (MNA) and p-nitroaniline (pNA), have been incorporated in Polyceram monoliths and thick films prepared by the hydrolysis and co-condensation of tetraethoxysilane and trimethoxysilylpropyl substituted polyethyleneimine. Strong second harmonic generation was observed.
Crystallization of Silicon Ion Implanted LPCVD Amorphous Silicon Films for High Performance Poly-TFT
Authors: Wu I-W. , Chiang A. , Fuse M. , Öveqoglut L. , Huang T. Y. 
Published: March 2011

AbstractThe mechanism of silicon ion implantation on the crystallization kinetics and the resulting grain sizes of LPCVD α-Si films have been studied by x-ray diffraction and transmission electron microscopy. The solid-phase crystallization was proceeded by random nucleation and growth from the Si/SiO2 interface. The most effective grain size enhancement was found by targeting the peak concentration of implanted siliconbeyond the Si/SiO2 interface, such that the maximum kinetic energy transfer occurred at that interface. The average grain size increases from ∼0.16 μm to ∼2.0 μm by a Si + implantation at 92KeV and a dose of 2X1015 cm-2 for 0.1 μm silicon film. X-ray diffraction intensities were analyzed to optimize implanting dose, beam current and energy for different film thickness. Grain size enhancement was achieved by retarding the random nucleation and increasing the nucleation activation barrier from ∼3.9eV to ∼4.9 eV for the implanted sample. The amorphous to crystalline growth activation barrier of ∼3.2 eV was not altered by Si+ implantation. The observed nucleation and growth kinetics change may be due to the chemical effect of the recoiled oxygen atoms from the substrate. The field-effect mobilities for both n- and p-channel TFTs increase by a factor of two with deep silicon implant.
Diffusion of as and B in Polysilicon/ Single Crystal Silicon Systems
Authors: Park K. , Batra S. , Banerjee S. , Lux G. , Manukonda R. 
Published: March 2011

AbstractComparative studies of As and B diffusion in polysilicon-on-single-crystal Si systems have been performed by Cross-sectional Transmission Electron Microscopy (XTEM) and Secondary Ion Mass Spectrometry (SIMS). Arsenic and BF2 implanted in 300 nm Low Pressure Chemical Vapor Deposition (LPCVD) polysilicon are diffused into the underlying Si substrate by Rapid Thermal Annealing (RTA) or furnace annealing. Diffusion profiles of Asappear to be continuous across the poly/single crystal Si interface except for a peak at the interface and show a gradual increase towards the interface within the polysilicon layer due to an inhomogeneous distribution of grain sizes in Asimplanted polysilicon layers. On the other hand, indiffusion of B gives a discontinuous doping profile at the interface due to accumulation of B-defect complexes created by dissolution of defectclusters in polysilicon. At low anneal temperatures, the B profiles in single crystal Siare shallower than the As profiles. This is because most of the B in polysilicon films is immobile during annealing near the peak region where the solid solubility limit is exceeded, and because of low B segregation at grain boundaries, thereby reducing the impactof grain boundaries in terms of high diffusivity. At high anneal temperatures, the native oxide at the interface breaks up and causes the polysilicon layer to align epitaxiallywith respect to the underlying substrate. Time to breakup of interfacial oxide depends on dopant species and anneal temperatures. Oxide breakup takes longer for As-doped samples than for B-doped samples. For high thermal budget anneals, B diffusion into the substrate is greater than As diffusion because of higher B diffusivities in single crystal Si.
Comparison of Amorphous and Polycrystalline Silicon Films as a Solid Diffusion Source for Advanced VLSI Processes
Authors: Park K. , Batra S. , Banerjee S. , Lux G. 
Published: March 2011

AbstractThis paper discusses the diffusion behavior of P, B and As from as-deposited amorphous/ polycrystalline silicon into the underlying Si substrate as a function of RTA/ furnace annealing conditions. The evolution of grain microstructure has been studied in as-deposited amorphous/ polycrystalline silicon to determine the inter-dependency of diffusion behavior and grain microstructure. After 60 s RTA at 1100° C for P doping, the microstructure of asdeposited amorphous silicon is drastically changed by rapid grain growth, whereas it is only slightly changed for asdeposited polysilicon. This leads to formation of deeper junctions for as-deposited polysilicon than for as-deposited amorphous Si. For B doping, there is little difference in the final microstructure between as-deposited polysilicon and as-deposited amorphous silicon after anneal. For low annealing temperatures, the junctions for both amorphous and polysilicon diffusion sources are laterally uniform in spite of local inhomogeneities due to grain boundaries. This is believed to be due to the rapid lateral spread of dopants along the interface prior to indiffusion into the substrate. At high annealing temperatures, a number of dark fringes are observed in the substrate along the interface from Crosssectional Transmission Electron Microscopy (XTEM) micrographs, which are more conspicuous for as-deposited amorphous Si. We believe that these fringes arise from local doping inhomogeneities or lattice strain in the substrate. For 30 s RTA at 1150° C, the native interfacial oxide appears to break up, causing epitaxial alignment of the polysilicon layer with respect to the underlying substrate.
Low Stress Silicon Nitride and Polysilicon Films for Micromachining Applications
Authors: Beck P. A. , Taylor S. M. , Mcvittie J. P. , Ahn S. T. 
Published: March 2011

AbstractReduced stress silicon nitride and undoped, as deposited, polysilicon films have been characterized on a variety of silicon based substrates within the confines of co-fabrication compatibility of micromechanical structures with VLSI processing. Average stress and stress uniformity through the films are shown to vary with substrate parameters.