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Strong fibers

Description: This program was directed to a new and generic approach to the development of new materials with novel and interesting properties, and to the precision fabrication of these materials in one and two-dimensional forms. Advanced deposition processes and microfabrication technology were used to produce fibers and grids of metals, semiconductors, ceramics, and mixtures of controlled composition and structure, and with new and interesting mechanical and physical properties. Deposition processes inclu… more
Date: March 1, 1991
Creator: Li, Che-Yu.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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CARBON NANOMATERIALS AS CATALYSTS FOR HYDROGEN UPTAKE AND RELEASE IN NAALH4

Description: A synergistic approach involving experiment and first-principles theory not only shows that carbon nanostructures can be used as catalysts for hydrogen uptake and release in complex metal hydrides such as sodium alanate, NaAlH{sub 4}, but also provides an unambiguous understanding of how the catalysts work. The stability of NaAlH{sub 4} originates from the charge transfer from Na to the AlH{sub 4} moiety, resulting in an ionic bond between Na{sup +} and AlH{sub 4}{sup -} and a covalent bond bet… more
Date: June 19, 2008
Creator: Berseth, P; Ragaiy Zidan, R & Andrew Harter, A
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Structure, Magnetism, and Transport of CuCr2Se4 Thin Films

Description: We report the successful growth of highly spin-polarized chalcogenide thin films of CuCr{sub 2}Se{sub 4}, which are promising candidates for spin-based electronic applications. We also present electronic structure calculations for CuCr{sub 2}Se{sub 4} that, together with magnetic and transport data, imply that the stoichiometric compound is a metallic ferromagnet with a relatively low density of hole-like carriers at the Fermi energy. These calculations also predict that a deficiency of Se will… more
Date: April 1, 2007
Creator: Bettinger, J. S.; Chopdekar, R. V.; Liberati, M.; Neulinger, J. R.; Chshiev, M.; Takamura, Y. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Adsorption of water on O(2x2)/Ru(0001): thermal stability and inhibition of dissociation by H2O-O bonding

Description: The effect of preadsorbed oxygen on the subsequent adsorption and reactions of water on Ru(0001) has been studied using low temperature scanning tunneling microscopy and DFT calculations. Experiments were carried out for O coverages close to 0.25 ML. It was found that no dissociation of water takes place up to the desorption temperature of {approx}180-230 K. DFT calculations show that intact water on O(2x2)/Ru(0001) is {approx} 0.49 eV more stable than the dissociation products, H and OH, at th… more
Date: August 1, 2008
Creator: Mugarza, Aitor; Shimizu, Tomoko; Cabrera-Sanfelix, Pepa; Sanchez-Portal, Daniel; Arnau, Andres & Salmeron, Miquel
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Chemical Bonding, Interfaces and Defects in Hafnium Oxide/Germanium Oxynitride Gate Stacks on Ge (100)

Description: Correlations among interface properties and chemical bonding characteristics in HfO{sub 2}/GeO{sub x}N{sub y}/Ge MIS stacks were investigated using in-situ remote nitridation of the Ge (100) surface prior to HfO{sub 2} atomic layer deposition (ALD). Ultra thin ({approx}1.1 nm), thermally stable and aqueous etch-resistant GeO{sub x}N{sub y} interfaces layers that exhibited Ge core level photoelectron spectra (PES) similar to stoichiometric Ge{sub 3}N{sub 4} were synthesized. To evaluate GeO{sub … more
Date: October 31, 2008
Creator: Oshima, Yasuhiro; /Stanford U., Materials Sci. Dept.; Sun, Yun; /SLAC, SSRL; Kuzum, Duygu; U., /Stanford et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Charge injection properties of iridium oxide films produced on Ti-6Al-4V alloy substrates by ion-beam mixing techniques

Description: The charge injection capabilities of iridium oxide films, as produced on Ti6Al-4V alloy substrates by ion beam mixing techniques, have been investigated. Iridium oxide is a valence change oxide, and therefore has high values of charge injection density upon voltage cycling in electrolytes. Because of this property, iridium oxide films are useful as working elements in neural prostheses. Iridium films of three thicknesses, produced by sputter deposition followed by ion beam mixing, were tested i… more
Date: October 1, 1991
Creator: Williams, J.M. (Oak Ridge National Lab., TN (United States)); Lee, I-S. & Buchanan, R.A. (Tennessee Univ., Knoxville, TN (United States))
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Performance Model for Molten Carbonate Fuel Cells. Quarterly Report, July 5, 1978 Through October 5, 1978

Description: Progress on the development of a performance model for molten carbonate fuel cells is reported. Key physical and chemical phenomena have been identified for inclusion in the model. In some instances, mathematical analyses of these phenomena have been begun. A numerical scheme to calculate the cell current density distribution has been developed. The scheme accounts for CO utilization and nonisothermal temperature distributions in the cell.
Date: 1978-23~
Creator: Bloomfield, D.; Finson, M. L.; Wilemski, G.; Wolf, T. & Wray, K. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Chemical vapor infiltration of TiB[sub 2] composites

Description: Efficiency of the Hall-Heroult electrolytic reduction of aluminum can be substantially improved by the use of a TiB[sub 2] cathode surface. The use of TiB[sub 2], however, has been hampered by the brittle nature of the material and the grain-boundary attack of sintering-aid phases by molten aluminum. In the current work, TiB[sub 2] is toughened through the use of reinforcing fibers, with chemical vapor infiltration (CVI) used to produce pure TiB[sub 2]. It has been observed, however, that the f… more
Date: January 1, 1993
Creator: Besmann, T.M.; Miller, J.H.; Cooley, K.C.; Lowden, R.A. (Oak Ridge National Lab., TN (United States)) & Starr, T.L. (Georgia Tech Research Inst., Atlanta, GA (United States))
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Direct observation of solute segregation to voids in a fast-neutron irradiated (Mo/1. 0 at. % Ti alloy

Description: The atom-probe field-ion microscope was used to study segregation effects to voids in a Mo--Ti alloy which had been irradiated with fast neutrons. The Ti does not segregate significantly to voids, concentration of Ti in solid solution and the spacial distribution of Ti was not affected by irradiation, carbon was not detected, resolution of TiC or MoC precipitates did not occur. (FS)
Date: November 1, 1978
Creator: Wagner, A. & Seidman, D.N.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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On Relative Permeability of Rough-Walled Fractures

Description: This paper presents a conceptual and numerical model of multiphase flow in fractures. The void space of real rough-walled rock fractures is conceptualized as a two-dimensional heterogeneous porous medium, characterized by aperture as a function of position in the fracture plane. Portions of a fracture are occupied by wetting and non-wetting phase, respectively, according to local capillary pressure and accessibility criteria. Phase occupancy and permeability are derived by assuming a parallel-p… more
Date: January 1989
Creator: Pruess, K. & Tsang, Y. W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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[Atomistic and elastic analyses of defects and small structures]. [Annual] progress report, [January 1, 1993--January 1, 1994]

Description: Focus was on interfacial segregation and its effect on interfacial phase stability. A method for performing atomisitc simulations in alloys was developed which accounts for equilibrium solute redistribution and allows determination of all thermodynamic properties. Segregation was shown to be strongly correlated with interfacial stresses on an atomic site-by-site basis and to greatly reduce the atomic level stresses, homogenizing the boundary. Differences in interfacial energies between elements… more
Date: August 1, 1994
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Defects and transport in mixed oxides. Progress report, [December 22, 1992--September 30,1993]

Description: Progress has been made in: nonstoichiometry of rock salt structure oxide solid solutions; cation tracer diffusion in oxide solid solutions of the types (Co,Mn){sub 3-{delta}}O{sub 4} and (Co,Fe){sub 1-{Delta}}O; electrical conductivity in solid solution (Co,Fe){sub 1-{Delta}}O; Monte-Carlo simulation of the cation diffusion in spinel solid solutions; thermodynamic modelling of the ternary phase diagram of the system Co-Fe-Mn-O and the boundary systems Co-Fe-O and Fe-Mn-O at 1200 C; and interdif… more
Date: September 30, 1993
Creator: Dieckmann, R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Atom-probe field-ion microscope for the study of the interaction of impurity atoms or alloying elements with defects

Description: A time-of-flight (TOF) atom-probe field-ion microscope (FIM) designed for the study of defects is described. This atom probe features: (1) a variable magnification internal-image-intensification system; (2) a liquid-helium goniometer stage; (3) a low-energy (less than or equal 3 keV) gas-ion gun for in-situ irradiations; (4) an ultra-high vacuum (approximately 3.10/sup -10/ torr) chamber; (5) a high vacuum (approximately 10/sup -6/ torr) specimen-exchange device; (6) a Chevron ion detector; and… more
Date: October 1, 1976
Creator: Wagner, A.; Hall, T. M. & Seidman, D. N.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Fundamentals of wetting and bonding between ceramics and metals

Description: The conditions and the reactions that lead to the realization of chemical equilibrium at interfaces and thus to chemical bonding is discussed with specific attention to the platinum/glass and gold/glass systems. Wetting of the solid by the liquid and formation of an interface are part of the problem. Sessile drop experiments and their interpretation are included. 10 figs, 12 refs. (GHT)
Date: January 21, 1977
Creator: Pask, J. A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The Parabolic Growth Op Oxide Solid Solutions on Binary Alloys: A Semi-Empirical Approach.

Description: The growth of solid solution oxide scales on alloys has been described by considering either the transport of the cations themselves, or that of the defect species in the oxide lattice. The two approaches have been shown to be similar. However, it has become apparent that the simplified defect model implicitly assumed in previous analyses using the ionic transport approach is not adequate to fully describe the variation of ionic diffusivities with oxygen potential or oxide composition. Further … more
Date: October 1, 1980
Creator: Whittle, D. P.; Gesmundo, F. & Viani, F.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Impact of transmission electron microscopy in ceramics. [Lithium ferrite]

Description: The impact that transmission microscopy has made in the study of ceramics is illustrated by the following examples from current work: an absolute structure determination, the study of precipitation and order-disorder phase transformations in lithium ferrite, phase transitions and polytypism in silicon carbide and the investigation of grain boundaries in silicon nitride at lattice resolution, particularly for the presence of amorphous phases.
Date: January 1, 1977
Creator: Thomas, G.; Clarke, D. R. & van der Biest, O.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Polarization-selective vortex-core switching by tailored orthogonal Gaussian-pulse currents

Description: We experimentally demonstrate low-power-consumption vortex-core switching in magnetic nanodisks using tailored rotating magnetic fields produced with orthogonal and unipolar Gaussian-pulse currents. The optimal width of the orthogonal pulses and their time delay are found, from analytical and micromagnetic numerical calculations, to be determined only by the angular eigenfrequency {omega}{sub D} for a given vortex-state disk of polarization p, such that {sigma}=1/{omega}{sub D} and {Delta}t={p… more
Date: October 13, 2010
Creator: Jung, H.; Choi, Y. S.; Yoo, M. W.; Im, M. Y. & Kim, S. K.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Final Report: A Transport Phenomena Based Approach to Probe Evolution of Weld Macro and Microstructures and A Smart Bi-directional Model of Fusion Welding

Description: In recent years, applications of numerical heat transfer and fluid flow models of fusion welding have resulted in improved understanding of both the welding processes and welded materials. They have been used to accurately calculate thermal cycles and fusion zone geometry in many cases. Here we report the following three major advancements from this project. First, we show how microstructures, grain size distribution and topology of welds of several important engineering alloys can be computed … more
Date: December 11, 2009
Creator: DebRoy, Dr. Tarasankar
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Orientation and thickness dependence of magnetization at the interfacesof highly spin-polarized manganite thin films

Description: We have probed the nature of magnetism at the surface of (001), (110) and (111)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films. The spin polarization of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films is not intrinsically suppressed at all surfaces and interfaces but is highly sensitive to both the epitaxial strain state as well as the substrate orientation. Through the use of soft x-ray spectroscopy, the magnetic properties of (001), (110) and (111)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/… more
Date: August 18, 2008
Creator: Chopdekar, Rajesh V.; Arenholz, Elke & Suzuki, Y.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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