bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas Phase Decomposition of an Organometallic Chemical Vapor Deposition Precursor to AIN:[AI(CH3)2NH2]3
Authors: Amato Carmela C. , Hudson John B. , Interrante Leonard V. 
Published: March 2011

AbstractA novel technique for probing chemical vapor deposition reaction mechanisms is presented. A conventional hot-wall Pyrex reactor is coupled to a molecular beam apparatus. Preliminary results of the decomposition of an organometallic precursor to AIN, [AI(CH3)2NH2]3, indicate a decomposition temperature between 200 and 270°C. The mass spectrum of the precursor at 100°C provides evidence for the existence of a trimer-dimer equilibrium of the precursor at this temperature
Correlation Among Process Routes, Microstructures and Properties of Chemically Vapor Deposited Silicon Carbide
Authors: Davis Robert F. 
Published: March 2011

Abstract“Silicon carbide” is a generic term for a host of different materials produced by several process routes which yield a variety of microstructures and associated property characteristics. The route of chemical vapor deposition (CVD) is used primarily to deposit SiC for wear- and corrosion- resistant coatings and for diffusion barriers to and from the underlying substrate. Presently this technique is also being used to deposit monocrystalline semiconductor thin films of SiC and to infiltrate various high temperature woven fabrics with this material. The following sections describe the results of thermodynamic calculations to define SiC CVD diagrams using various precursor gas mixtures, discuss various CVD techniques and detail the results of deformation, infiltration and thin film deposition studies that have been recently conducted on vapor deposited SiC.
Microstructural Characterization of Multiphase Coatings Produced By Chemical Vapor Deposition
Authors: Lowden R. A. , More K. L. , Besmann T. M. , James R. D. 
Published: March 2011

AbstractChemical vapor deposition has been utilized to produce ternary, multiphase coatings of various compositions of silicon carbide (SiC) with Ti, Cr, and Mo. Thermodynamic calculations have been performed for a variety of experimental conditions in each system. Scanning, transmission and analytical electron microscopy, and X-ray diffraction techniques have been used to characterize the microstructures and to determine compositions.
Tungsten Carbide Erosion Resistant Coating for Aerospace Components
Authors: Garg D. , Dyer P. N. 
Published: March 2011

AbstractAn increasing problem faced by the aerospace industry is the erosive wear of engine components. Various PVD protection coatings have been used previously to combat this wear problem, but with limited success. This paper presents results obtained with a low-temperature CVD, erosion resistant, multilayer tungsten carbide coating system. The coating can be deposited at temperatures below 500°C on ferrous alloys used in the aerospace industry. The low temperature of deposition eliminates the problem of degradation of mechanical properties that occurs with normal high-temperature chemical vapor deposition processes. High-cycle fatigue strength and other mechanical property data are presented for coated stainless steel, as well as results on erosion and impact resistance at 90° impingement.
Effects of Deposition Conditions on The Microstructure and Properties of CVD SiC
Authors: Minford Eric , Stevens Robert E. , Magnotta Vincent L. , Dyer Paul N. , Watkins Thomas R. , Green David J. 
Published: March 2011

AbstractAs part of an ongoing program to develop high performance silicon carbide coatings for graphite, a research study into the effects of deposition conditions on residual stresses was initiated. A series of experiments was conceived and implemented to explore the microstructure and the elastic properties of the coatings and substrates as well as to directly measure the residual stress states. The results of these experiments are analyzed with respect to the effects of deposition temperature on the microstructure and properties of CVD SiC on graphite and how the observed differences affect the residual stresses in the coatings.
Bond Graphs For Cvd Processes
Authors: Kalidindi Surya R. , Desu Seshu B. 
Published: March 2011

AbstractA unified approach to model the general CVD process, utilizing the versatility and flexibility of bond graph methods, is presented. The bond graph representations for important CVD sub-processes are derived. The application of these elements is illustrated through hypothetical examples of CVD processes. It is also shown that several different CVD processes can be handled by a single bond graph computer program.
Organometallic Chemical Vapor Deposition of Strontium Titanate thin Films
Authors: Feil W. A. , Wessels B. W. , Tonge L. M. , Marks T. J. 
Published: March 2011

AbstractSrTiO3 thin films were deposited by low pressure organometallic chemical vapor deposition on silicon substrates using the volatile metal-organic precursors titanium isopropoxide and Sr(dipivaloylmethanate)2. Oxygen and water vapor were used as reactant gases and argon was used as a carrier gas. Growth rates ranging from 0.6–2.1 μm/hr were obtained at 650–800°C. Polycrystalline films were obtained at growth temperatures of 650–750°C, and amorphous films above 750°C. SrTiO3 films deposited on silicon substrates exhibited resistivities greater than 109 Ω-cm and dielectric constants up to 100.
Early Growth in the Chemical Vapor Deposition of Tin and TiC and Monitoring by Laser Scattering
Authors: Klein Max , Gallois Bernard 
Published: March 2011

AbstractThe early growth of chemically vapor deposited TiN and TiC coatings on pyrolytic graphite was studied in the kinetic- and mass transport-controlled regimes. While steady-state growth of these coatings results in columnar grains, such morphologies do not originate at the substrate/coating interface. Rather, TiC deposition begins on the substrate as fine grains less than 100 nm in diameter. Early TiN growth occurs in layers of 50 nm grains. In both cases, early fine-grained growth occurs at a lower rate than the linear, steady rate observed for columnar growth. A laser scattering technique has been developed as a tool for characterizing early growth through surface roughness. This noncontact method can be used as an in-situ diagnostic to detect changes in the surface of the growing deposit.
Xps Analysis of Y-Ba-Cu-O and Zr-O Thin Films and Interfaces with Silicon Substrates
Authors: Fenner D.B. , Viano A.M. , Connell G.A.N. , Boyce J.B. , Fork D.K. , Ponce F.A. , Tramontana J.C. 
Published: March 2011

AbstractThin films of Y1Ba2Cu3Ox,ZrO2, and yttria-stabilized zirconia (YSZ) have been deposited on Si(100) by the UV-laser ablation technique, and characterized by several techniques including x-ray photoemission spectroscopy (XPS) and cross-sectional transmission electron microscopy (XTEM). Si substrates were prepared by several techniques including thermal oxidation, and oxide etching and passivation by hydrogen termination. Certain of these YBCO films (= 250 nm thick) deposited on YSZ buffer layers have excellent superconducting properties. Other YBCO and zirconia films, deposited to 2-5 nm thickness and transferred under dry N2 into UHV, allowed XPS evaluation of the thermal and chemical stability of the interfaces and nearby regions. 2-nm films of YBCO on 15-nm films of SiO2/Si, deposited at 550–670 °C, showed Cu 2p core-level XPS lines similar to those of bulk YBCO (i.e., Cu II) but with two components due to reactions. The Si 2p line showed formation of silica on the YBCO surface at 670 °C and of silicate at 550 °C. XTEM lattice images showed that use of H-terminated Si produced superior interfaces with the zirconia films.
Phonon Anomaly at Tc In (Y/Er)Ba2Cu3O7–δ
Authors: Sharma Rajeshwar P. , Rehn L. E. , Baldo P. , Liu J. Z. 
Published: March 2011

AbstractIon channeling in single crystals of (Y/Er)Ba2Cu3O7–δ reveal an abrupt change (~0.01Å) at the superconducting transition temperature (Tc) in displacements of the Cu and O atoms perpendicular to the [001] direction. This anomalous change in atomic displacements shifts directly with stoichiometry-induced changes in Tc. Blocking patterns indicate no large structural changes across Tc.
Magnetic Penetration Depth and Intragrain Critical Current Density in Grain-Aligned Tl2Ca2Ba2Cu3O10 Superconductor
Authors: Thompson J. R. , Christen D. K. , Deeds H.A. , Kim Y. C. , Brynestad J. , Sekijla S.T. , Budai J. , Ossandon J. G. 
Published: March 2011

AbstractMagnetic studies were performed on the high temperature superconductor Tl2Ca2Ba2Cu3O10 (Tc = 123 K) in the form of a grain aligned composite. Investigations with the magnetic field applied parallel and perpendicular to the sample's cannon c-axes were analyzed to obtain the magnetic penetration depth as a function of temperature and the critical current density Jc(H,T).
Bulk Modulus of the YBaCuO Oxide Superconductor Obtained from Magnetic Measurements
Authors: Bokhimi  
Published: March 2011

AbstractStarting from the fact that the YBa2Cu3O7-x oxide superconductor system has a constant magnetic susceptibility at high temperatures for each oxygen deficiency x, and assuming that the charge carriers have a free-electron-like behavior, the observed magnetic susceptibility of the samples at room temperature can be associated to the Pauli paramagnetismus and to the Landau diamagnetism of the charge carriers. This result allows one to calculate the charge carriers density from the magnetic susceptibility in the sample. If besides one assume that by applying an external pressure on the sample, there is a change of the volume of the unit cell, but not in the number of the charge carriers in it, then, it is possible to calculate the Bulk modulus of the YBaCuO system at room temperature starting from these magnetic measurements. The obtained results are of the same order of magnitude to those reported in the literature and obtained from thermodynamic and mechanical measurements.
Rf Surface Resistance Measurements in the Pb-Bi-Sr-Ca-Cu-O System
Authors: Lanagan M. T. , Bohn C. L. , Delayen J. R. , Einloth M. C. , Vogt R. N. , Balachandran U. 
Published: March 2011

AbstractWires were fabricated from the high-Tcsuperconductor Bi0.7Pb0.3SrCaCu1.8Ox(Pb-BSCCO) by an extrusion process. The specimens were sintered for periods up to 14 days, and density was found to decrease with longer sintering times. Rf surface resistance data revealed that the onset of superconductivity occurred at 105 K and that the transition was very broad.
Fabrication of High TC Superconducting Composite Structure
Authors: Chang J. , Song L.W. , Barone R. , Bush P. , Yang F. , Patel S. , Kao Y.H. , Shaw D.T. 
Published: March 2011

AbstractThe laser ablation technique was used to fabricate high Tc superconducting composite structures. The multilayered structures were fabricated in‐situ by changing the target during deposition. Thin MgO films and yttrium‐stabilized Zr02 films were used as buffer layers. The composite films were successfully fabricated on ZrO2(100) substrates. There is negligible interdiffusion occurring at the interfaces and the Jc at 77K is higher than 105A/cm2 for YBCO films in a triple layered structure.
Effect of Thermal Cycling and Mechanical Deformation on the Superconducting Properties of Ag/Yba2Cu3O7-X Wires
Authors: Ocampo M.A. , Orgaz E. , Akachi T. 
Published: March 2011

AbstractPreforms made by filling silver tubes with YBa2Cu3O7‐x (YBCO) powder were drawn to obtain wires with diameters in the 0.25mm to 1.00mm range. Straight samples of these wires were sintered and oxygenated. The observed changes in Tc and Jc while the samples were thermaly cycled or mechanically deformed are reported.
Phase Equilibria in the System Tl-Ca-Ba-Cu-O. I. Stability of the 2122 Phase Under Conditions of Oxygen Annealing
Authors: Cook L. P. , Chiang C. K. , Wong-Ng W. , Swartzendruber L. J. , Bennett L. H. 
Published: March 2011

AbstractResults are presented for 850°C oxygen annealing experiments (up to 62 hr) on the 2122 (Tl:Ca:Ba:Cu) oxide phase, with and without intermediate grinding. Samples were characterized by powder X-ray diffraction and a.c. magnetic susceptibility. The 2122 phase appears to be thermodynamically stable in oxygen under conditions of both extensive grinding, and, annealing of long duration. However, onset Tc's vary from 71 K to 109 K for apparently single-phase 2122 samples with nearly identical X-ray powder patterns, depending upon the heat treatment.
Oxygen Ordering in Yba2cu3oz at Low Temperature
Authors: Ceder G. , Asta M. , Fontaine D. de 
Published: March 2011

AbstractA parameter‐free phase diagram is derived for oxygen ordering in the YBa2Cu3Oz compound. Four phase regions are found in which the following structures are stable: Tetragonal, Ortho I, Ortho II, and anti‐Ortho I. In addition, long‐period quasi‐one‐dimensional states of order can become stable at low temperature. A simple branching algorithm allows one to predict these additional structures and their diffraction patterns. Theoretical predictions are in excellent agreement with recent experimental findings. Implications for the existence of Tc plateaus are briefly discussed.
Non-Stoichiometry and Complex Defects in the Structure of R-Ba-Cu-O Single Crystals Determined by Neutron Diffraction
Authors: Schweiss P. , Galez Ph. , Collin G. , Marucco F. 
Published: March 2011

AbstractThe crystal structure of several RBa2Cu3-yO6+z (R=Y,Ho) crystals are investigated by neutron diffraction using an exact solution for the twinned orthorhombic samples. For an oxygen concentration >0.35 in the chains, the structure is orthorhombic due to an exclusive occupancy of the 0(4) site. A systematic and variable copper deficiency is observed on the Cu(l) site leading to a correlated defect on the chain oxygen O(4) and on the bridging oxygen O(l). Due to the presence of these defects, a transverse disorder is observed for the highest oxygen content with a residual occupancy of the forbidden O(5) site.
Superconductivity Above 77 K in the Cubic Ba2Ycu2Wo9-Y Oxide System
Authors: Bokhimi  , Garcia-Ruiz A. 
Published: March 2011

AbstractWe have obtained a new family of oxide superconductors, which are characterized by a cubic structure with the space group Fm3m and transition temperatures to the superconducting state above 77 K. As prototype of this family, we have studied some properties of the Ba2YCu2WO9‐y system. We report details about the experimental conditions that are necessary in order to obtain the cubic structure and to change the charge carrier density. The samples show superconducting behavior around 90 K with only a small Meissner effect fraction. These results can be interpreted in terms of filamentary superconductivity, however, it is necessary to characterize the system further to give a correct interpretation of the results.
Preparation and Transition Temperature of Ca‐Substituted Yba2Cu4O8
Authors: Miyatake T. , Yamaguchi K. , Takata T. , Gotoh S. , Koshizuka N. , Tanaka S. 
Published: March 2011

AbstractSamples of Y1‐xCaxBa2Cu4O8 are prepared by means of a new high pressure technique employing the oxygen‐HIP. We find that the transition temperature increases with Ca content, and that Tc=90K is realized at x=0.1. These data are explained by the hole concentration, i.e. average charge per [Cu‐O] site.
KEY‐WORDS: YBa2Cu4O8, Ca‐substitution, Transition temperature, Hole concentration
Seeding Induced Aligned Microstructures (S.I.A.M.) in Yba2Cu306+X
Authors: Zhang Lijie , Chan Helen M. , Harmer Martin P. 
Published: March 2011

AbstractAnnealing of YBa2Cu_Og (12 3) above the peritectic temperature, followed by slow cooling at 0.5 C/min, was found to produce a microstructure containing regions (d ‐ 200 microns) within which the grains were highly aligned. When these regions were used to “seed” 123 powder, an enhanced degree of texture was obtained, where the aligned regions were > 1mm in size.
Influence of Starting Material on Bi2sr2cacu2o8 Fibers Grown by the Float Zone Process
Authors: Moulton Linda V. , Brenner Joseph M. , Raymakers Robert J. , Peszkin Perla N. , Feigelson Robert S. 
Published: March 2011

AbstractA miniaturized float zone technique using laser heating has been found to have potential for producing superconducting fibers of Bi2Sr2CaCu2O8 which can carry high currents. Growth stability and growth rate, however, need to be improved if this technique is to be useful for preparing long lengths of 30 μπι diameter high quality fibers for property evaluation and prototype devices. One of the first requirements toward achieving this goal is the preparation of dense, homogeneous starting material. Work on different strategies for starting material preparation are discussed.
Theory of the Normal State of Cuprate Superconductors
Authors: Anderson Philip W. , Ren Yong 
Published: March 2011

AbstractWe propose a framework for the theory of the "normal" metallic state of the CuO2 planes of high Tc superconductors. This state is closely analogous to the known state of the one-dimensional Hubbard model, with spin excitations which can be thought of as chargeless (Z = 0) Fermions occupying the interior of the conventional Fermi surface, and charged excitations which have zero energy near the spanning vectors 2kF of that Fermi surface. The electron spectrum is the composite spectrum of two of these excitations, and can be fitted to angle-resolved photoemission data. When we do so we can calculate or estimate many properties of the normal state in excellent agreement with experiment, and show that the pair susceptibility is anomalously large and temperature-dependent, explaining the high Tc and the specific heat behavior.
110K Superconducting Fibers of [Bi,Pb(Sb)]2Sr2Ca2Cu2O10 + x
Authors: Jincang Zhang , Aisheng He , Yujing Huo , Yusheng He 
Published: March 2011

AbstractSuperconducting fibers of [Bi,Pb(Sb)]2Sr2Ca2Cu3O10 + x high Tc superconducting materials have been prepared by means of the laser-heated pedestal growth method with Tc 0= 110K and Jc>103 A/cm2. Structure analysis showed that the a-b plane of the material prefers to align along the growth direction, though the post-growth heat treatment, which is still necessary at present stage, may destroy the texture structure in some extent.The existence of Pb is vital for stabilizing the 110K phase of the Bi-based fibers.
Superconductivity of Bi-Sr-Ca-Cu-O Prepared from CuO or Cu2O, and Doped with Ag Ions
Authors: Kato Teruo , Kazumata Yukio , Maeta Hiroshi 
Published: March 2011

AbstractSuperconductivity in Bi compounds is examined in samples prepared from CuO and Cu2O powders, and also in samples doped with Ag. In BiSrCaCuxO (x=2,3,4,5) prepared from CuO powder, Tc decreases with an increase of Cu content, while in samples prepared from Cu2O the opposite trend, an increase of Tc with Cu content, is observed. From Ag doping, BiSrCaCu2Oy+Agx (x=0, 1.0, 1.5, 2.0), the volume ratio of high to low Tc phase is found to be a maximum at a Ag content between 1.5 and 2.0. From these experiments, a strong correlation between the high Tc phase and Cu+ valence state is suggested.
Hyper- and Hypobaric Processing of T1-Ca-Ba-Cu-O Superconductors
Authors: Goretta K. C. , Routbort J. L. , Shi Donglu , Chen J. G. , Xu Ming , Hash M. C. 
Published: March 2011

AbstractTl-based superconductors of initial composition Tl:Ca:Ba:Cu equal to 2:2:2:3 and 1:3:1:3 were heated in oxygen at pressures of 104 to 6 x 105 Pa. The 2:2:2:3 composition formed primarily the 2-layer superconductor with zero resistance from 77 to 104 K. The 1:3:1:3 composition formed nearly phase pure 3-layer superconductor with a maximum zero resistance temperature of 120 K. Application of hyperbaric pressure influenced phase purities and transition temperatures slightly; phase purities decreased significantly with application of hypobaric pressures.
Ag/YBa2Cu3O7-x Powder Generation by Aerosol Decomposition
Authors: Kodas Toivo T. , Carim Altaf H. , Ott Kevin C. 
Published: March 2011

AbstractYBa2Cu3O7-x (123) powders containing silver have been prepared by aerosol decomposition. Metal nitrate solution droplets were decomposed at temperatures above and below the melting point of the Ag-O eutectic. In both cases, the Ag was present as a separate grain attached to YBa2Cu3O7-x. Individual aerosol particles had dimensions of 50 – 1000 nm. Grain sizes of Ag and 123 crystallites within these particles were 10 to 100 nm. Larger 123 grain sizes could be obtained by varying the reactor operating conditions. The powders provide a source of material for generation of YBa2Cu3O7-x/Ag ceramics with smaller Ag and 123 grain sizes and more uniform composition than can be obtained by other methods.
The Evaporative Decomposition of Solutions Method (Eds) for the Production of Ultrafine Y1Ba2Cu3O7 from Nitrate and Mixed Anion Precursor Solutions
Authors: Lakis Rollin E. , Butler Sidney R. 
Published: March 2011

AbstractY1Ba2Cu3O7 has been prepared by the evaporative decomposition of solutions method. Nitrate and mixed anion solutions were atomized and decomposed at temperatures ranging from 300°C to 950°C. The resulting materials have been characterized using x-ray powder diffraction, Thermal Gravimetric Analysis (TGA), particle size analysis, Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). The powder consists of 0.3 micron agglomerated hollow spheres with a primary particle size of 0.06 micron. TGA and x-ray diffraction indicate the presence of barium nitrate and barium carbonate due to incomplete decomposition and/or product contamination by the process environment.
Metal-Organic Precursors to high Temperature Superconductors Using 2-(2-Ethoxyethoxy)Ethanol
Authors: Scozzafava Mary Rose , Rhine Wendell E. , Cima Michael J. 
Published: March 2011

AbstractThe copper(II) alkoxide, bis(2-(2-ethoxyethoxy)ethoxide)copper(II), was prepared and had a solubility in organic solvents greatly exceeding those of simple copper(II) alkoxides (>0.4 mol/L in toluene at room temperature). Copper 2-(2-ethoxyethoxy)ethoxide (2-(2-ethoxyethoxy)ethoxide = 2,2-EEE) toluene or toluene/THF solutions gelled upon exposure to moisture. These solutions were hydrolysed with 0.2, 1.0, 2.0, 4.0, and 20.0 equivalents of H2O and the resulting powders were characterized by IR spectroscopy and SEM.
Magnetic Alignment of Bi and T1 Cuprates Containing Rare Earth Elements (II)
Authors: Chen Feng , Markiewicz Robert S. , Giessen Bill C. 
Published: March 2011

AbstractContinuing an earlier study, we report new data on the orientational effects of magnetic field alignment of some bismuth cuprates and 8 additional thallium cuprates. Strong parallel alignment is seen for Lu bismate and Nd, Sm and Ho thallate; strong normal alignment is seen for Tm; however, in contrast to bismates and 123 phase, Tl cuprates show little anisotropy among directions within the basal plane.
Structural Aspects of the Phase Separation in La2CuO4.032
Authors: Chailloutl C. , Bordetl P. , Chenavasl J. , Cheong S.W. , Fisk Z. , Mareziou M. , Morosin B. , Schirber J.E. 
Published: March 2011

AbstractThe average structure of superconducting La2CuO4.032 has been determined by single crystal neutron diffraction data. The excess oxygen is located between two adjacent LaO layers. Its presence distorts the apical‐oxygen sublattice in such a way that a short O‐O bond is formed (1.64Å). By scanning several hkl reflexions, we have confirmed that a phase separation occurs below room temperature. The peaks of the phases are in agreement with the unit cells proposed by Jorgensen et al. and Zolliker et al. However, Cmca seems to be the correct space group for both phases. La2CuO4+მ and the Ni counterpart are, thus, not isostructural.
Ybco Films and Buffer‐Layers Grown In‐Situ by Pulsed Laser Deposition
Authors: Connell G. A. N. , Fenner D. B. , Fork D. K. , Boyce J.B. , Ponce F.A. , Bridges F. , Geballe T.H. 
Published: March 2011

AbstractYSZ [ (Y2O3)x (ZrO2)1‐x ] buffer‐layers for various compositions, x, and YBCO (Y1Ba2Cu3O7‐δ) films were grown on hydrogen‐terminated Si(100) substrates by laser ablation. The structural and electrical properties of the YBCO are found to depend strongly on x, and to be optimized near x=0.1.