bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bond Strength of Pressed Composites
Authors: Wiegand Donald A. 
Published: March 2011

ABSTRACTComposites samples containing 80% and 85% organic filler in a polymer-plastizer binder were produced by mixing, extruding, cutting, drying and pressing. Before pressing the extruded material was in some cases coated with a thin layer of graphite (= one micron) for ease in pressing. As part of a general study of these composites the compressive strength, σm, was determined as a function of temperature, strain rate and the thickness of the graphite coating. Without graphite σm increases with decreasing temperature and increasing strain rate. With graphite σm has the same behavior above approximately −10 C, but is independent of both temperature and strain rate below −10 C for a strain rate of 1.0/Sec. In addition, the low temperature value of Om decreases with increasing graphite thickness. The cracking and fracture patterns are temperature and strain rate dependent and are different with and without graphite. These results indicate that the bond produced by pressing the graphite containing material is stronger than the composite above −10 C and weaker below −10 C so that failure initiates in the composite above −10 C and in the bond below −10 C. With decreasing strain rate this transition temperature decreases. The bonding is discussed.
High Sensitivity FT-IR-Ras for Silicon Surface Study
Authors: Ohshima Hisayoshi , Urisu Tsuneo , Yamada Yoshiyasu , Hattori Tadashi 
Published: March 2011

ABSTRACTA novel configuration for Fourier-transform infrared reflection absorption spectroscopy (FT-IR-RAS) has been devised to study the nature of silicon wafer surfaces in the wide IR irradiation region (especially below 1300 cm−1) with high sensitivity. The configuration is basically similar to a conventional one of FT-IR-RAS except that a optical-flat mirror is placed on a silicon wafer surface and the IR beam is incident on the back side of the wafer with a grazing angle. The sensitivity of the novel technique was estimated by the observation of the stretching vibration absorption of the Si-Hx bond (2070-2150 cm−1) on HF/NH4F-treated Si(111) surfaces and Si-O bond (1000-1250 cm−1) of chemically oxidized layer ( ∼0.7 nm ) on Si(111) surfaces. The dependence of Si-Hx absorption peaks intensities on the composition of HF/NH4.F solutions was clearly observed. Furthermore, Si-O bond peak corresponding to the longitudinal optical phonon was also detected.
Infrared Spectra of Ultra-Thin SiO2 Grown on Si Surfaces
Authors: Yamazaki T. , Miyazaki S. , Bjorkman C. H. , Fukuda M. , Hirose M. 
Published: March 2011

ABSTRACTThe structure of thin SiO2 films thermally grown on Si(100) and Si(111) surfaces has been characterized by using infrared internal reflection and x-ray photoelectron spectroscopy. It is found that the infrared absorption peak due to the LO phonon mode originating from the Si-O-Si stretching vibration shows a considerable red shift in the thickness range below 30A. This red shift is interpreted in terms of the compressive stress near the interface.
New Analytical Method of SiO2 Structure by Infrared Reflection Absorption Spectroscopy (Ir-Ras)
Authors: Ishikawa K. , Ogawa H. , Inomata C. , Fujimura S. , Mori H. 
Published: March 2011

ABSTRACTSimulation of a thin oxide RAS spectrum obtained by using the dielectric function extracted from thick oxide RAS spectra is shown to be a viable method for the comparison of oxide films of differing thickness. Bulk and near-interfacial features of thermally grown SiO2 thin films were studied by this method and it was found that the LO phonon peak at about 1255 cm−1 reflects bulk SiO2 structure and a higher reflectance between 1100 and 1200 cm−1 reflects SiO2/Si interface structure.
The Enabling Role of Surface Passivation in Visible Photoluminescence from Si Nanoparticles
Authors: Seraphin A.A. , Werwa E. , Chiu L.A. , Kolenbrander K.D. 
Published: March 2011

ABSTRACTSilicon nanocrystallites have been studied in a variety of passivating environments to study the role of surface passivation in visible light emission from the particles. Thin films of Si nanocrystallites have been deposited by a laser ablation supersonic expansion technique. The films show significant room temperature photoluminescence (PL) behavior only after processing to achieve surface passivation. Passivation effects on light emission are studied through PL emission spectroscopy on clusters in the gas phase, as well as films in a variety of passivating media. The intensity of PL emission seems to scale with the extent of surface passivation, but the specific nature of the passivating species is not critical in defining the wavelength of emitted light.
The Model for Description of Electrical Properties of Polymerization-Filled Composite Materials
Authors: Tchmutin I.A. , Ponomarenko A.T. , Shevchenko V.G. 
Published: March 2011

ABSTRACTThe conductivity behavior found in polymerization-filled composites differs from that predicted by percolation theory and can be explained by a simple model predicting the existence of two characteristic values in such systems: the radius of filler particles and the distance of charge penetration into polymer matrix. Detailed mechanisms, responsible for such peculiarities in charge transfer are also discussed.
The Influence of Silicon Overlayers on the Electrical Conductivity of Very Thin Chromium Films
Authors: Aleshin Andrej N. , Schroder Klaus 
Published: March 2011

ABSTRACTThe influence of silicon overlayers on the electrical conductivity of 5 nm to 10 nm thick chromium films has been studied. It was found that the deposition of silicon decreases the resistivity of Cr-film by up to 24 %. Possible mechanisms for the resistance decrease due to the silicon overlayer are discussed.
Optical Characterization of Buried Ingaas/GaAs Wires Overgrown by MBE
Authors: Pieger K. , Straka J. , Gréus Ch. , Forchel A. 
Published: March 2011

ABSTRACTWe have prepared buried InGaAs/GaAs wires by high resolution electron beam lithography, wet chemical etching and subsequent MBE overgrowth. Wires with lateral widths of less than 40nm have been realized.For optimized regrowth conditions such as growth temperature, growth rate, III/V ratio, and arsenic flux a smooth surface morphology of the 100nm thick overgrown (Al)GaAs layer is obtained.Etched only ultra narrow wires show a decrease of radiative recombination due to process induced defects and surface recombination at the open sidewalls. Optical investigations of narrow overgrown wires show a significant enhancement (up to two orders of magnitude) of the photoluminescence intensity. This is due to the disappearance of the open sidewalls and carrier capture from the overgrown barrier.From studies of the influence of the crystallographic orientation on the quantum efficiency we find, that <111>B surfaces of the <011> wires offer the best conditions for MBE overgrowth.
Interfacial Effects in Polycaproamide-Aramide Polymer Systems
Authors: Dmitrenko Vladimir P. 
Published: March 2011

ABSTRACTThe peculiarity of interdiffusion and phase equilibrium has been studied for poly-m-phenyleneisophthalamide and poly-p-amidobenzimidazole systems during formation of a transitional layer in conditions of organoplastics. The investigation of this process has been based on the method of electron-probe X-ray spectral microanalysis. The effect of temperature, pressure and time of thermal treatment on dimensions of diffusional zones and kinetics of their formation was shown. The parameters of solubility and mutual diffusion of components were determined and phase diagrams were obtained.
Adhesion of Tungsten Fine Lines on SiO2 by Micro-Wedge Scratching
Authors: de Boer M. P. , Huang H. , Nelson J. C. , Wang F. , Gerberich W. W. 
Published: March 2011

ABSTRACTMicroscratch testing of thin films has mainly been done with a conical tip. In the wedge scratch technique introduced in this paper, thin film fine lines are scratched by a wedge-shaped diamond tip until a spallation occurs. A near plane strain situation arises, and finite element method (FEM) analysis is applied for more accurate evaluation of the work of adhesion. The material system used to demonstrate the micro-wedge scratch technique is rf-sputtered tungsten on thermally grown SiO2. When scratching a long line, delamination occurs by two mechanisms. At loads above 8-9mN/µm (normal load per unit line width), tensile stresses behind the indenter tip cause the tungsten to crack, and the thin film subsequently curls up. At loads above 1lmN/µm, high shear stresses in front of the indenter cause delamination of the tungsten at the interface. This latter event is modeled by FEM using a bimaterial fracture mechanics approach to obtain a practical work of adhesion value.
Characterization of Ti/TiN Films and SiO2/Ti Interfaces by Use of X-Ray Photoelectron Spectroscopy
Authors: Bernard Joffre , Adem Ercan , Ramaswami Seshadri 
Published: March 2011

ABSTRACTThe deposition and processing of thin films, such as barrier metals and anti-reflective coatings, can be enhanced using the information provided by various surface analysis techniques. We will show the application of x-ray photoelectron spectroscopy(XPS) to the production of Ti and TiN films suitable for use in ULSI CMOS integrated circuits. XPS can separate Ti and N photoelectron peaks and detect low (1.0-5.0 atomic%) contamination levels while providing surface and interface chemical state information. In this paper we will show that a) the effect of TiN deposition on subsequent Ti film quality from the same Ti target was determined to be minimal, b) the relation of anneal temperature to the extent of SiO2 reduction by Ti metal was characterized on SiO2/Ti/TiN structures for temperatures from 600°C to 800°C, and c) the absorption of O into TiN films from ambient air was detected and confirmed.
STM Studies of Ultra-Thin Overlayers of Cu on SrTiO3(001) Surfaces
Authors: Liang Yong , Carroll D. L. , Bonnell Dawn A. 
Published: March 2011

ABSTRACTScanning tunneling microscopy has been used to study the initial stage of Cu growth on SrTi03(001) surfaces. Our STM results show that Cu grows initially into 3-D island-like structures. Two different morphologies were observed. In some areas loosely bound individual Cu islands appear preferentially attached to step edges. The islands were frequently relocated by the STM tip during the scanning as a result of tip-surface interaction. Other areas have higher densities of Cu islands that exhibit a narrow size distribution with an average diameter of 70 Å and are homogeneously distributed on those areas. The driving force for the morphological evolution of Cu on the SrTiO3(001) surface is discussed in terms of surface free energy and interfacial interaction of metal on transition metal oxide surfaces.
Microstructural Evolution and Stress Relaxation in Sputtered Tungsten Films
Authors: Ross F. M. , Kola R. R. , Hull R. , Bean J. C. 
Published: March 2011

ABSTRACTWe have investigated the relationship between microstructure and stress in very thin sputtered W films. We discuss features of the microstructure, in particular the presence of voids in compressively stressed films, in terms of the evolution of the structure from a metastable β-phase. By developing a novel specimen geometry for the transmission electron microscope (TEM), we present dynamic observations of the β-W→α-W transformation.
The Role of Gel Processing in The Preparation of Catalyst Supports
Authors: Cairns J.A. , Segal D.L. , Woodhead J.L. 
Published: March 2011

ABSTRACTCatalyst supports are required to meet a wide range of objectives, including chemical purity and composition, optimised surface area/porosity and thermal stability. Gel processing offers means by which many of these requirements can be achieved. In addition, the use of sols of controlled rheology allows the support material to be prepared in a form which facilitates its application to substrates (including metals) as a coating, thereby greatly improving its versatility for producing novel catalysts. The preparation of typical support materials will be discussed, together with examples of their use in catalysis.
Synthesis, Characterization, and Processing of Monosized Ceramic Powders
Authors: Fegley Bruce , Barringer Eric A. 
Published: March 2011

ABSTRACTControlled alkoxide hydrolysis reactions for the synthesis of monodispersed oxide powders are described. The chemical and physical properties of representative monodispersed powders of TiO2, doped TiO2, ZrO2, doped ZrO2, SiO2, doped SiO2, and ZrO2-Al2O3 are described. The importance of surface chemistry for control of powder dispersion and packing is discussed and related to the control of sintered microstructures.
Lead Zirconate-Lead Titanate (PZT) Ceramics From Organic-Derived Precursors
Authors: Dosch R. G. 
Published: March 2011

ABSTRACTOrganic-derived precursors can facilitate the preparation of PZT ceramics, particularly in the areas of processing and batch reproducibility. The use of partially alkoxide-derived precursors and completely organic-derived precursors has been studied. Two methods of alkoxide hydrolysis were evaluated for preparing zirconia which included direct hydrolysis in water and hydrolysis of alkoxide-base reaction products in acetone-H2O mixtures. The chemistry of these methods is discussed along with pertinent aqueous surface chemistry of the hydrated zirconia products. This work suggests that alkoxide-derived precursor properties are related to the solution chemistry used in their preparation.
Chemical Analyses of Sol/Gel Surfaces and Thin Films
Authors: Pantano Carlo G. , Houser C. A. , Brow R. K. 
Published: March 2011

ABSTRACTThe application of surface analysis techniques to the characterization of sol/gel surfaces and thin films is described. Secondary-ion mass spectroscopy (SIMS), x-ray photoelectron spectroscopy (XPS) and sputter-induced photon spectroscopy (SIPS) are used to measure the composition of multicomponent silicate films, the relative water content of alumina films, the nitrogen content of ammonia treated silica films, and the depth profiles for films on black chrome. The determination of chemical structure using XPS and SIMS is also discussed. Finally, a brief introduction to temperature-programmed desorption (TPD) and its potential for studying surface chemical reactions, in situ, is presented.
In Situ FT-IR Studies of Oxide and Oxynitride Sol-Gel-Derived Thin Films
Authors: Haaland David M. , Jeffrey Brinker C. 
Published: March 2011

ABSTRACTA high-temperature infrared cell was developed to study the gel-to-glass conversion of sol-gel-derived thin films. FT-IR spectra of matched thin-film borosilicate sol-gel samples were taken as the samples were heated at 100°C intervals to 700°C in either air or ammonia. The gels were converted to oxide and oxynitride glasses, respectively, by these heat treatments. The gel-to-glass conversion could be followed and compared for these two treatments by monitoring changes in the vibrational bands present in the spectra. Comparisons between the infrared spectra of NH3-treated and air-treated films heated above 500°C reveal the appearance of new B-N bonds at the expense of B-O-Si bonds for the NH3-fired films. These spectra also exhibit changes which may indicate the formation of Si-N bonds. Thus, ammonolysis reactions can result in thin-film oxynitride glass formation at relatively low temperatures.
Characterisation of Concentrated Colloidal Suspensions for Ceramic Processing
Authors: Stewart R F , Sutton D 
Published: March 2011

ABSTRACTCharacterisation and control of the structure and properties of particulate solids suspensions is of widespread importance with respect to many operations, such as separation, dispersion and densification in the ceramics and related industries. In this paper we describe techniques which have been used to study the effects of changes in basic parameters, for example solids content, particle size, electrolyte concentration and added polymer on the aggregated suspension morphology and characteristics. Suspension morphology was examined by a number of methods, notably freeze-etch microscopy. The mechanical properties of suspensions such as their compressional modulus and rheological behaviour was also examined.
Tetraethylorthosilicate (Teos)
Authors: Klein L. C. , Garvey G. J. 
Published: March 2011

ABSTRACTTwo series of gels were prepared by hydrolyzing TEOS with HCl or NH4OH catalyst. In the first series, the molar ratio of water to TEOS was 4:1 and the catalyst addition was (1 × 10−3), (4 × 10−3), (1 × 10−2), (4 × 10−2), and (1 × 10−1). In the second series, the catalyst addition was (1 × 10−3) moles and the molar ratio of water to TEOS was 2:1, 4:1, 8:1, 16:1, and 32:1. Dried samples were characterized for surface area, porosity and C and H content. Samples were heated to 800°C and thermogravimetric weight loss was recorded. Both HCl and NH4OH are catalysts for hydrolysis, but during polymerization, the relative rates of hydrolysis and condensation determine resulting dried microstructures.
Sol-Gel Derived Ceramic-Ceramic Composites using Short Fibers
Authors: Lannutti J. J. , Clark D. E. 
Published: March 2011

ABSTRACTShort ceramic fibers or whiskers may be ideally suited for the fabrication of ceramic-ceramic composites using the sol-gel process. The fibers can be uniformly dispersed in a low viscosity sol and then frozen into the matrix through gelation. Several ceramic composites were prepared by synthesizing an Al2O3 precursor from aluminum sec-butoxide and then dispersing fibers of either zirconia, graphite or SiC. The composites were dried at room temperature and fired up to 1200°C. The fibers reduce the volume shrinkages in comparison to that obtained with pure Al2O3 during processing. Structures with dimensions of several cm2 can be rapidly produced with this method without cracking.
Long Fiber Reinforced Sol-Gel Derived Al2O3 Composites
Authors: Lannutti J. J. , Clark D. E. 
Published: March 2011

ABSTRACTA simple casting technique was used to fabricate composites comprised of long fibers in an alumina matrix. Random fiber preforms were placed in trays and subsequently a liquid alumina sol was added and gelled. Dried sheets approximately 6 cm in diameter and 0.2 cm thick were prepared without cracking. The addition of glycerol to the sol improved drying properties, made the dry gel flexible, and permitted the lamination (plying) of several sheets.
The Ceramist as Chemist - Opportunities for New Materials
Authors: Uhlmann D. R. , Zelinski B.J.J. , Wnek G.E. 
Published: March 2011

ABSTRACTThe use of sol-gel techniques to prepare glasses and crystalline ceramics offers outstanding opportunity for breakthroughs in technology. The areas of particular promise include novel glasses; crystallineceramics with exceptional microstructures; coatings for modification of electrical, optical, mechanical and chemical properties; porous media with high surface area and tailored chemistry; ceramic powders with high chemical homogeneity and narrow distributions of particle size; matrix materials in ceramicceramic composites; and a wide spectrum of specialty ceramic materials, ranging from abrasives and fibers to glass ceramics and films. Opportunities in each of these areas will be discussed and related to the advances in understanding and process technology required for their achievement. The theses will be advanced that creative chemistry provides the key to many of these advances, that ceramists simply MUST learn more chemistry, but that we dare not rest from our labors when the chemistry is done.
Local Structure Surrounding Implanted As+ Ions in Polysulfone Films
Authors: Mayanovic R. A. , Feng Y. , Groh K. W. , Wang Y. , Giedd R. E. , Moss M.G. 
Published: March 2011

ABSTRACTResults from As K-edge XAFS studies on polysulfone films implanted with 50 KeV As+ in the dose range of 1015 to 1016 ions/cm2 indicate that As reacts chemically with O atoms to form As- (3) 0 based molecular structures having As-0 bond lengths equal to 1.81±0.02 Å. In comparison to samples implanted in the dose range 101S to 1016 ions/cm2, the molecular environment surrounding As in polysulfone implanted at 1017 ions/cm2 has additional structure beyond the nearest-neighbor O atoms.
Structural Analysis of Amorphous Phosphates Using High Performance Liquid Chromatography
Authors: Sales B. C. , Boatner L. A. , Chakoumakos B. C. , Mccallum J. C. , Ramey J. O. , Zuhr R. A. 
Published: March 2011

ABSTRACTThe technique of high-performance liquid chromatography (HPLC) provides unique detailed information regarding the structure of partially disordered or amorphous phosphate solids. Applications of the experimental technique of HPLC to phosphate solids are reviewed, and examples of the type of information that can be obtained with HPLC are presented.
Generalized Activation Energy Spectrum Theory: A New Approach for modeling Structural Relaxation in Amorphous Solids
Authors: Shin Jung H. , Atwater Harry A. 
Published: March 2011

ABSTRACTA general approach to the dynamics of structural relaxation in amorphous solids is developed. A form of the recombination kinetics of defects is chosen which removes the ad hoc assumption made in previous theories that defects recombine only with others of identical activation energy. The generalized theory is tested quantitatively by modelling the structural relaxation of amorphous silicon, and comparing the results with the experimental data on structural relaxation. It is found that the generalized theory is necessary in order to accurately describe the time-resolved relaxation data. The generalized theory is also applied to estimate the effect of irradiation on the nucleation kinetics of crystal silicon, and is found to agree well with experimental data.
Strain Relaxation and Oxide Formation on Annealed W/C Multilayers
Authors: Geisz J. F. , Phang Y. H. , Kuech T. F. , Lagally M. G. , Cardone F. , Potemski R. M. 
Published: March 2011

ABSTRACTTungsten-carbon (W/C) Multilayer structures are used as X-ray mirrors and other optical elements. The optical properties of such elements are highly sensitive to changes in strain due to thermal processing. Sensitive curvature measurements were performed on 40A period W/C Multilayer structures on Si substrates using a two beam laser reflection technique. A compressive stress of approximately 1530 MPa was measured in these sputtered multilayer films. Thermal annealing to 500 C in air and under vacuum resulted in very little strain relaxation in the multilayers but X-ray diffraction data show a slight increase of the multilayer period. Significant strain relaxation, though, was observed when a 400Å W buffer layer was included. Thermal annealing of these samples to 400–500°C resulted in large strain relaxation due to the formation of a-W crystals in the buffer layer. Moderate oxide formation on air annealed samples as measured by SIMS was shown not to be a dominant mechanism of strain relaxation.
Evidence of Silica Polymerization During Internal Nucleation of Glassy Lithium Disilicate
Authors: Adams Jane W. , De Jong Bernard H.W.S. 
Published: March 2011

ABSTRACTThe principal problem in developing a theory of internal nucleation lies in the constitution of the nascent nuclei. To get at this constitution in an internally nucleating glass, oxygen and lithium core level x-ray photoelectron spectra have been measured on glassy and nucleated lithium disilicate and on the three stable crystalline compounds in the Li2O-SiO2 system. Our results indicate that nucleated lithium disilicate glass consists of completely polymerized silica in the formation of which non-bridging oxygens are consumed. During this silica polymerization lithium atoms move away from presumably four-fold coordinated sites towards higher coordinated ones.