bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemically Bonded Ceramics as an Alternative to High Temperature
Composite Processing
Authors: Gulgun Mehmet A. , Johnson Bradley R. , Kriven Waltraud M. 
Published: April 2011

ABSTRACTProcessing of multi-phase ceramic composite materials using chemically
bonded ceramics as a binding agent appears to be a promising route for
fabricating complex-shaped structures. In a zirconia-calcium aluminate
ceramic matrix composite, the hydraulic property of fine, monocalcium
aluminate (CaAl2O4) powders was used to prepare strong
prefired bodies.The changes in the physical characteristics of the composite during the
conversion from a chemically bonded compact into a sintered composite were
studied using thermogravimetric analyses (TGA), X-ray diffraction and
scanning electron microscopy. The density and the hardness of the chemically
bonded and sintered composite were measured.
The Use of Superlattice Reactants in The Synthesis of Ternary
CU‐NB‐SE Compounds
Authors: Hornbostel Marc D. , Fukuto Masafumi , Johnson David C. 
Published: April 2011

ABSTRACTThe low temperature interdiffusion of superlattice reactants of the binary
systems niobium‐selenium and copper‐selenium and the ternary
copper‐niobium‐selenium were explored to synthesize amorphous reaction
intermediates. Controlled crystallization of this intermediate, which
depends upon nucleation energetics rather than the thermodynamic stability
of the final product, was used as we attempted to prepare ternary niobium
cluster compounds. We present data demonstrating the ability to prepare
amorphous ternary intermediates without the formation of crystalline binary
compounds as reaction intermediates. Crystallization of the amorphous
intermediate resulted in the formation of known ternary compounds directly,
also without the formation of binary compounds.
Preparation And Characterization Of Ultra-Small Sized Metal And
Semiconductor Particles In Sol-Gel Materials
Authors: Choi Kyung Moon , Shea Kenneth J. 
Published: April 2011

ABSTRACTPoly(l,4-phenylene)-bridged and poly(1,6-hexylene)-bridged silsesquioxanes
(PPS and HPS) were prepared by the sol-gel process. The surface areas and
pore diameters of these porous xerogels were obtained by BET and BJH
methods, respectively. These porous materials were used as a confinement
matrix for the growth of small-sized semiconductor and transition metal
clusters. Quantum-sized CdS particles in PPS (approximately 58+12 Â) and HPS
(91+16 Â) matrices were prepared by first soaking the xerogel in a
CdCl2 solution. Following a washing with water, a Na2S
solution was then added. EDAX and electron diffraction techniques were used
to identify the CdS particles. The particle sizes of CdS in PPS and HPS were
determined by both UV measurements and from TEM images. Small-sized Cr
clusters were prepared in dried xerogels by an internal doping method. Mixed
Cr/CdS phases were also prepared by internal loading of a chromium metal
precursor. Following deposition of CdS the xerogel was heated at 120 °C
under high vacuum, resulting in formation of intimately mixed phases of Cr
metal and CdS. Changes in morphology, in particular the surface area and
pore size distribution were noted. A decrease in surface area and an
increase in pore size were observed as a result of Cr metal deposition.
Micrqporous Silica Gels from Alkylsilicate-Water Two Phase
Hydrolysis
Authors: Chu L. , Tejedor-Tejedor M. I. , Anderson M. A. 
Published: April 2011

ABSTRACTMicroporous silica gels have been synthesized through a nano-particulate
sol-gel route. These gels have uniformly distributed and extremely small
pores(< 15Â in diameter). Hydrolysis and condensation reactions leading
to these gels were carried out in an alkyl silicate-water (ammonia) two
phase system. These reactions took place at the alkyl silicate droplet-water
interfacial boundary. No alcohol was added. A clear, stable and uniformly
distributed colloidal silica suspension having an average particle size less
than 6 nm was prepared by this method. Fast hydrolysis, slow condensation
and low solubility all contribute to a high supersaturation level and result
in the formation of small particles. This process is consistent with classic
nucleation theory. When the particles are produced under acidic rather than
under basic reaction conditions, smaller particles are formed due to the
slower condensation rate and lower solubility of these silica particles in
acidic conditions. At the same pH, alkylsilicates having smaller alkyl
groups react faster with water leading to smaller primary particles.
Homogeneous nucleation conditions are achieved when the water/alkylsilicate
ratio is high.
Dynamics of Liquids in Confined Geometries
Authors: Xu Shu , Korb J.-P. , Jonas J. 
Published: April 2011

ABSTRACTAn overview of several NMR studies of liquids in confined geometries is
presented. First, the NMR relaxation rates, 1/T1,
1/T1ρ , and 1/T2 were measured for several
molecular liquids confined to porous silica glasses with pore radii in the
range from 12 Å to 100 Å as a function of temperature, pore size, and
frequency. The experimental relaxation data were interpreted in terms of
bulk, surface, and topological contributions using the following
expression:where 1/Tib and 1/Tis are the bulk and the surface
layer relaxation rates, ε is the thickness of the surface layer, R is the
pore radius, and Ai(ω) represents the pure topological
effect.Second, the pressure effects on the dynamics of the confined liquid of
acetonitrile-d3 were also investigated. Third, the natural
abundance of 13C spin lattice relaxation rates for CS2
confined to porous silica glasses provided information about confinement
effects on the angular momentum behavior of this simple liquid.
Fullerenes Entrapped in Porous Glass
Authors: Borrelli N.F. , Smith C. , Smith D.W. 
Published: April 2011

ABSTRACTFullerenes have been impregnated in porous glass with little interaction with the glass noted. Concentrations as high as 3mg/ml of C60 or C70 were obtained. It was shown that the fullerenes can enhance the photo-induced charge transfer reaction of DEA with the porous glass.
Studies of C60 Films Deposited Using Ionized Cluster Beam Deposition Technique
Authors: Ren Zhong-Min , Du Yuan-Cheng , Ying Zhi-Feng , Xiong Xia-Xing , He Mao-Qi , Li Yu-Fen , Li Fu-Ming 
Published: April 2011

ABSTRACTFilms (with thicknesses about thousands A) of a new form of carbon allotrope, CIO also known as Fullerenes, are deposited on Si(111) substrates using ionized cluster beam deposition (ICBD) technique at low (65V) accelerating voltage V. X-ray &-20 diffraction (XRD) have been used to investigate the structural properties of C6Ofi lms, indicating hexagonal close-packed structure with strong (002) XRD assignment together with weak (100), (112) and(004) assignments. Raman spectra, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) are carried out to make detailed studies of the electronic properties of the films and to illustrate differences between CO films and amorphous carbon films which are deposited by ICBD at high accelerating voltage V >400V. Cio soccer-balls are found to be broken into fragments as accelerating field overtakes about 400V, indicated by the results of XPS, Raman spectra, XRD, and UV/visible absorption spectra.
Electronics Application for Fullerenes
Authors: McNally R.L. , Brotzen F R. , Griffin A.J. , Loos P.J. , Barrera E.V. 
Published: April 2011

ABSTRACTThin-film Al-C60-Al trilayered structures were sublimated under ultra high vacuum (UHV) conditions for the purpose of investigating their current-voltage (I-V) properties. These metal-semiconductor-metal devices exhibited rapid and irreversible drop in resistance of about two orders of magnitude under an applied voltage of 0.67 to 0.75V. Approximate initial and final resistances were 1050 Ω and 8 Ω respectively. Wavelength Dispersive Spectroscopy (WDS) indicated no noticeable change in phase of the fullerene inter-layer after the irreversible drop in resistance. These results, SEM micrographs and concentration profiles were concordant with diffusion of top layer Al through the fullerene layer as the most likely cause of the change in resistance.
The Effects of Molecular Orientation on the Electronic Structure of the Solid Fullerites
Authors: Gu Bing-Lin , Maruyama Yutaka , Yu Jing-Zhi , Ohno Kaoru , Kawazoe Yoshiyuki 
Published: April 2011

ABSTRACTThe effects of C60 molecular orientation and rotation on the electronic structure of fcc C60 solid have been investigated by performing a band structure calculation with self-consistent mixed-basis all electron and full-potential approach within local density approximation. We present an angle-dependent density of states of HOMO and LUMO bands, which should be compared to the angle-resolved photoemission data.
Highly Sensitive Analysis for Valence Band Edge of C60 Films by Total Yield Photoelectron Spectroscopy
Authors: Gonda S. , Kawasaki M. , Arakane T. , Koinuma H. 
Published: April 2011

ABSTRACTWe have in-situ measured the density of states (DOS) around the top of valence band of pristine C60 films by means of total yield photoelectron spectroscopy. The top of valence band (TVB) of C60 was located at 5.00eV below the vacuum level. Considerable amplitude of gap states was observed up to 0.9eV above the TVB. Kelvin probe method revealed that the Fermi level of amorphous C60 film was located at 0.47eV above the TVB. The improvement of crystallinity in C60 films, which induced the increase in electrical conductivity as well, increased the DOS above the TVB. The electric conduction of C60 films cannot be explained with a simple picture for carrier conduction in semiconductors.
Synthesis of Carbo-Nitride Films Using High-Energy Shock Plasma Deposition
Authors: Gurarie V. N. , Orlov A. V. , Nugent K. W. , Weiser P. , Prawer S. 
Published: April 2011

ABSTRACTThe present work reports on the properties of nitrogen rich carbon films produced by an intense gas discharge between carbon electrodes in a nitrogen atmosphere. The energy of the discharge, initial nitrogen pressure, number of discharges and geometry are varied to establish their effect on the nitrogen content and the mechanical, structural and morphological characteristics of the deposited carbon-nitride films. The structural diagnostics include optical and scanning electron microscopy, as well as Auger and Raman Spectroscopes and Rutherford Backscattering. The C-N films formed fell into two categories, differing in morphology and mechanical properties. Type I are C-N films, containing up to 35 at. % nitrogen, and which have an amorphous structure. These films are formed at relatively low plasma shock pressure and exhibit relatively low microhardness, ̴ 2 GPa. In a relatively narrow range of the plasma shock pressure and temperature the second type of C-N deposition is observed consisting of high density, closely-packed crystal-like grains growing perpendicular to the substrate surface and displaying a cauliflower-like morphology, The microhardness of these films reaches 15 GPa, as measured by the Vickers method.
On The Role of Penetration Twins in The Morphological Development of Vapor-Grown Diamond Films
Authors: Tamor Michael A. , Everson Mark P. 
Published: April 2011

ABSTRACTBy control of deposition conditions, the morphologies of vapor-deposited polycrystalline diamond films may be varied deliberately from clean multi-micron crystallites to nanocrystalline ‘cauliflower’ nodules. Most attempts to connect diamond film ‘quality’ to growth conditions focus on competitive growth of non-diamond phases. In contrast, we propose that twinning is potentially the dominant factor. We develop a geometric parameterization of growth conditions to define conditions under which a common type of twin - the < 111> penetration twin - can outgrow and potentially bury the parent face on which it originated. We then show how the full range of CVD diamond crystal and film morphologies might be explained entirely in terms of penetration twins. This explanation does not entail reference to the actual mechanism of diamond growth. The geometric parameterization also suggests a ‘reactor map’ which serves as a powerful tool in process development and control.
Novel Structure of Microporous Activated Carbon Fibers and Their Gas Adsorption
Authors: Enoki Toshiaki , Kobayashi Norikazu , Nakayama Atsuko , Suzuki Kazuya , Ishii Chiaki , Kaneko Katsumi , Hosokoshi Yuko , Kinoshita Minoru , Endo Morinobu , Shindo Norifumi 
Published: April 2011

ABSTRACTActivated carbon fibers are a kind of microporous carbon. Using dangling bond spins attached to the peripheries of the micropores, we investigated the microporous structures in relation to the heat-treatment and gas adsorption effects. Functional groups weakly bonded to the graphitic backbone are removed by the heat-treatment at moderate temperatures 200-400°C, resulting in the generation of a variety of dangling bond spins. The heattreatment above 500°C brings about homogenization of the dangling bond spins. For gas adsorption, the introduction of helium gas strongly enhances the spin-lattice relaxation rate for the dangling bond spins. In addition to a remarkably large condensation of helium gas in the microporous region, the enhancement proves the presence of ultra-micropores which can accommodate only the smallest diameter helium atoms.
Intrinsic Stress in Sputtered Thin Films
Authors: Nguyen Tai D. , Nguyen Tue , Underwood James H. 
Published: April 2011

AbstractUnderstanding of the stress in thin films is important in controls of the properties of nanometer period x-ray multilayers. Stress evolution at the initial stages of thin film formation was studied by molecular dynamics simulation of Mo atoms impinging on a 5×5×5 unit cell Mo substrate. The simulation shows that the structure initially increases in a compressive state. The stress then decreases when the deposited atoms have covered the substrate surface. Measured stress of Ru films in Ru/C multilayers by laser curvature technique shows similar behavior to the simulated results.
Underlayer Effects on the Growth Stress of Titanium Films
Authors: Poppeller M. , Abermann R. 
Published: April 2011

AbstractThe growth stress of titanium films was measured in situ with a cantilever beam technique under UHV conditions at Ts ≥ 130°C. The substrate used in these experiments was a double layer consisting of a base layer of A12O3 or of MgF2 and as a second layer a titanium film evaporated at different H2O-partiaI pressures (Ti/TiOx). With both base layers the growth stress of the substrate Ti/TiOx layer is similar.The main objective of this paper was the investigation of the effect of a variation in the chemical composition of the substrate Ti/TiOx layer on the growth stress and -by way of our stress model - on the growth mode of a clean titanium film always evaporated under identical vacuum conditions onto this bilayered substrate. At low water content of the substrate titanium layer (the substrate layer still consists of metallic titanium) the growth of the clean titanium film is a continuation of the growth of the second substrate layer. As soon as the substrate titanium film contains only a few percent of water the initial compressive stress is overcompensated by atensile stress contribution which increases as the water content of the substrate isincreased. We interprete this to indicate renewed nucleation for the clean titanium film on the substrate surface. A small part of the tensile stress is also due to gas interdiffusion (hydrogen) from the substrate film. This effect is rather small when the second substrate film consists of stoichiometric oxide. With a MgF2 base layer in the substrate bilayer the results indicate a diffusing species from the MgF2 base layer into the Ti/TiOx layer. This interdiffusion from the substrate significantly affects the growth stress of the clean titanium film on this substrate bilayer. However, the general trends due to the incorporation of water in the substrate Ti/TiOx film, seen in case of the A12O3 base layer, are the same.
Brillouin Light Scattering Investigation of the Elastic Properties of Ta/Al Metallic Superlattices
Authors: Carlotti G. , Fioretto D. , Socino G. , Xia Hua , Hu An , Jiang S. S. 
Published: April 2011

AbstractThe Brillouin light scattering technique has been exploited for investigating the elastic properties of periodic superlattices made by alternating layers of Ta and Al. These multilayers, deposited by d.c. sputtering on glass and Si substrates, present a polycrystalline structure with (110) and (111) texture for the Ta and Al layers, respectively. They have total thicknesses of about 0.5 μm and periods ranging from 4 to 10 nm. Measurement of the phase velocities of the Rayleigh and Sezawa acoustic modes from the frequency position of the corresponding Brillouin peaks, yielded informaton on the effective elastic constants of the superlattices. for large periods (8-10 nm) the values determined experimentally are in good agreement with those calculated from the elastic constants of the bulk materials, while for lower periods (4-6 nm) the estimated elastic constants exhibit a marked increase. This anomalous behavior has been attributed to the presence of a transition layer at each interface, where Ta and Al interdiffuse, as observed by x-ray and electron microscopy experiments.
Measurement of Residual Stress In TiO2 Sol-Gel Thin Films Using Raman Spectroscopy
Authors: Hess Nancy J. , Exarhos Gregory J. 
Published: April 2011

AbstractThe deposition of thin films can result in residual stresses that affect film properties such as optical properties, phase stability, chemical durability, and film adhesion. There are many components to the total residual stress measured in a film. These include interfacial stress, volume changes associated with phase transitions, film thickness, and film microstructure. For sol-gel films, some contributors to residual stress can be controlled by such variables as the precursor chemistry and gelation time or heat-treatment following deposition. Measurements of the state of stress during crystallization or as a function of processing conditions and sol-gel chemistry allows optimization of film deposition parameters that promote minimal residual stress. We have constructed a three-dimensional surface in Raman shift-pressure-temperature space from spectroscopic measurements on single crystal anatase at high pressure and temperature. Location of the Raman shift of the two Eg modes of anatase on this surface the state of stress (pressure) and temperature of the film can be determined. For materials with large Raman scattering cross-sections, such as anatase, time-resolved crystallization experiments on films as thin as 100 nm are possible. Using this technique, the evolution of the state of stress during isothermal thermal and laser-induced crystallization processes can be monitored in real time and compared to the residual stress upon cooling.
Error Analysis In Nanoindentation
Authors: Shafirstein G , Gee M G , Osgerby S , Saunders S R J 
Published: April 2011

AbstractThis paper describes the results of an analysis of the errors that can arise during nanoindentation, and their effect on the final results. The sources of errors that have been considered are calibration errors in load, displacement, instrument frame compliance and indenter shape assuming a Berkovich indenter with an error in the included angle, and operational errors such as thermal drift and specimen tilt. An assessment of calibration errors indicates that a simple summation of errors was not appropriate in this case, since compliance and area function are depended upon displacement. Thus the error analysis has been carried out using a cumulative approach. As expected it was found that the errors increased with decreasing load and displacement, and increasing hardness and Young’s modulus. However, minimum errors were observed at about 20 mN and were a function of the indented materialNo appreciable error was found in the hardness or Young’s modulus calculated from load-displacement data at surface angles below 8°; above this value the indenter started moving sideways over the surface, resulting in significant errors.
Mechanical Properties of Platinum Films on Silicon and Glass Determined by Ultra-Microindentation
Authors: Mencik Jaroslav , Swain Michael V. 
Published: April 2011

AbstractPlatinum films of thickness 0.5 - 1.2 - 3.0 μm, deposited by magnetron sputtering onto glass and silicon, were investigated using ultra-microindentation. The tests were done with a pointed (Berkovich) indenter. The values of the hardness and elastic modulus of the composite “film + substrate” and the substrates alone were obtained for various loads and depths of penetration, and used to evaluate the hardness and elastic modulus of the films. The use of various film thicknesses and substrates has enabled us to investigate in more detail the influence of the contact radius/contact depth compared to the film thickness as well as the substrate properties on the total indentation behaviour. Various approaches to the data evaluation are discussed in the paper.
Effect of Stresses in Thin Films on Defect Nucleation
Authors: Nandedkar A. S. 
Published: April 2011

AbstractComputer simulations were used to investigate the effect of stresses on the energy of defects in Ge, Ge7% Si93% (referred to as alloy) films on Si and encapsulated aluminum thin films. In Ge films, misfit dislocations were energetically favorable over coherent interfaces. Although the alloy films had lower energy compared to Ge films, they also formed dislocations at film thicknesses greater than 25 – 30 Å. The energy of vacancy insertion at the film surface, which nucleates a misfit dislocation, increased with tensile stress. In encapsulated aluminum, agglomeration of vacancies leads to formation of voids. Simulations indicate that the activation energy of vacancy migration increased with compressive stresses. Thus compressive stresses in aluminum may prevent formation of voids, while tensile stresses in Ge film may prevent formation of misfit dislocations.
Stress and Adhesion of CVD Copper and TiN
Authors: Nguyen Tue , Evans David R 
Published: April 2011

AbstractThe use of copper for interconnect metallization on advanced submicron integrated circuits is attractive because of its inherent low resistivity. To date, chemical vapor deposition (CVD) processes which produce copper films with nearly bulk resistivity and good uniformity have been produced. However, adhesion of the copper deposit to underlying barrier materials, in particular to titanium nitride (TiN), has been problematic. In this work, adhesion has been measured using both a qualitative and a semi-quantitative method and has been correlated with process conditions and precursor formulation.
Material Properties and Related Considerations for Magnetomechanical Sensing Devices
Authors: Garshelis Ivan J. 
Published: April 2011

AbstractSuitability of specific materials for use in magnetomechanical sensors more often depends on combinations of properties than on an outstanding value of a single property. These combinations include ratios and products of properties from different physical families. While magnetic, magnetoelastic, electrical and strength properties often play key roles in determining the performance of the sensor, non-physical characteristics such as manufacturability, available forms, environmental compatibility, toxicity and costs strongly influence the device design and may well dominate the final choice of material. The development of materials specifically for use in this class of sensors is encouraged by their already broad and growing range of applicability.