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Mass transport through polycrystalline microstructures

Description: Mass transport properties are important in polycrystalline materials used as protective films. Traditionally, such properties have been studied by examining model polycrystalline structures, such as a regular array of straight grain boundaries. However, these models do not account for a number of features of real grain ensembles, including the grain size distribution and variations in grain shape. In this study, a finite difference scheme is developed to study transient and steady-state mass tr… more
Date: December 31, 1994
Creator: Swiler, T. P.; Holm, E. A.; Young, M. F. & Wright, S. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Effect of glass composition on waste form durability: A critical review

Description: This report reviews literature concerning the relationship between the composition and durability of silicate glasses, particularly glasses proposed for immobilization of radioactive waste. Standard procedures used to perform durability tests are reviewed. It is shown that tests in which a low-surface area sample is brought into contact with a very large volume of solution provide the most accurate measure of the intrinsic durability of a glass composition, whereas high-surface area/low-solutio… more
Date: November 1, 1994
Creator: Ellison, A. J. G.; Mazer, J. J. & Ebert, W. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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The development of mechanical strength in a ceramic material during firing

Description: This experiment was designed for high school students who have a very limited background in ceramic materials, but the experiments could also be used at the college level. The objective of the experiment is to teach students about the development of mechanical strength in a ceramic material as a result of the firing process and about testing methods used for brittle materials. In the experiment, clay-based ceramic bars of uniform circular cross section are prepared by extrusion. The bars are th… more
Date: November 1, 1994
Creator: Bunnell, L. R. & Piippo, S. W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Radiation-induced grain boundary segregation in austenitic stainless steels

Description: Radiation-induced segregation (RIS) to grain boundaries in Fe-Ni-Cr-Si stainless alloys has been measured as a function of irradiation temperature and dose. Heavy-ion irradiation was used to produce damage levels from 1 to 20 displacements per atom (dpa) at temperatures from 175 to 550{degrees}C. Measured Fe, Ni, and Cr segregation increased sharply with irradiation dose (from G to 5 dpa) and temperature (from 175 to about 350{degrees}C). However, grain boundary concentrations did not change si… more
Date: November 1, 1994
Creator: Bruemmer, S. M.; Charlot, L. A.; Vetrano, J. S. & Simonen, E. P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Explosive bonding and its application in the Advanced Photon Source front-end and beamline components design

Description: Explosive bonding is a bonding method in which the controlled energy of a detonating explosive is used to create a metallurgical bonding between two or more similar or dissimilar materials. Since 1991, a number of explosive-bonding joints have been designed for high-thermal-load ultrahigh-vacuum (UHV) compatible components in the Advanced Photon Source. A series of standardized explosive bonded joint units has also been designed and tested, such as: oxygen-free copper (OFHC) to stainless-steel … more
Date: December 1, 1994
Creator: Shu, D.; Li, Y.; Ryding, D.; Kuzay, T. M. & Brasher, D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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[Aluminum Coordination and Active Sites on Aluminas, Y-Zeolites and Pillared Layered Silicates]. Progress Report

Description: This report is organized in four sections. In the first the authors will outline structural features which are common to all fine grained alumina, as well as to non-framework alumina in zeolites. This section will be followed by a study of the surface vs. bulk coordination of aluminum. The third section will deal with measurement of the number of acid sites and the scaling of their strength. The fourth and last section will describe three model reactions: the isomerization of 1-butene and of 2 … more
Date: February 1, 1994
Creator: Fripiat, J. J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Oxygen stoichiometry and its influence on superconductivity in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+x}

Description: Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+x} (2212) was synthesized from freeze-dried precursors. The oxygen content of 2212 was determined as a function of temperature and oxygen partial pressure and the variation of Tc with oxygen content was determined. It was found that 2212 without excess oxygen (x = 0) is superconducting. This points to the role of the (Bi-O){sub {infinity}} layers as a source for holes in 2212. Four probe resistivity measurements were also performed on 2212. The nature of oxy… more
Date: December 31, 1994
Creator: Krishnaraj, P.; Lelovic, M.; Eror, N. G. & Balachandran, U.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Experimental and theoretical studies on the C15 intermetallic compounds MV{sub 2} (M = Zr, Hf and Ta): Elasticity and phase stability

Description: The phase stability of C15 HfV{sub 2} was studied by specific heat measurements. The elastic constants of C15 HfV{sub 2} were measured by the resonant ultrasound spectroscopy. Total energy and electronic structure of C15 intermetallic compounds MV{sub 2} (M = Zr, Hf and Ta) were calculated using the linear muffin tin orbital (LMTO) method. The band structures at X-point near the Fermi level were used to understand the anomalous shear moduli of the C15 HfV{sub 2} and ZrV{sub 2}. It was found tha… more
Date: December 1, 1994
Creator: Chu, F.; Mitchell, T. E.; Chen, S. P.; Sob, M.; Siegl, R. & Pope, D. P.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Development of high temperature, corrosion resistant polymer concrete for use in the steam distribution system of the Consolidated Edison Company of New York. Final report

Description: The results of a research program conducted by Brookhaven National Laboratory (BNL) to evaluate and develop polymer concrete (PC) materials, which can be used as an alternative material of construction to conventional steel-reinforced portland cement concrete (PCC) within the steam distribution system of Consolidated Edison Company of New York (Con Ed), are presented. Three fiber-reinforced PC systems were identified and evaluated in a series of laboratory and in situ field tests. Based upon th… more
Date: November 1, 1994
Creator: Webster, R. P.; Kukacka, L. E.; Reams, W. & Miller, C. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Processing and electrochemical properties of mixed conducting La{sub 1-x}A{sub x}Co{sub 1-y}Fe{sub y}O{sub 3-{delta}} (A=Sr, Ca)

Description: Powder compositions in the series La{sub 1-x}A{sub x}Co{sub 1-y}Fe{sub y}O{sub 3-{delta}} (A = Sr, Ca) have been prepared by a combustion synthesis method. Sintering of pressed powders produced high-density test specimens with the perovskite structure. The specimens exhibited high electrical conductivities with appreciable oxygen-ion conductivity that increased with Co content for the compositions studied. Oxygen permeation studies showed a significant flux of oxygen that increased with tempera… more
Date: November 1, 1994
Creator: Weber, W. J.; Stevenson, J. W.; Armstrong, T. R. & Pederson, L. R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Cooling rate effects on the microstructure, critical current density, and {Tc} transition of one- and two-powder BSCCO-2223 Ag-sheathed tapes

Description: An important variable controlling the critical current density (J{sub c}) of Ag-sheathed BSCCO-2223 tapes is the degree of phase purity of the reacted tapes. Most correlations between J{sub c} and microstructure show that it is highly desirable to reduce the amount of non-superconducting second phases to as low a level as practical. In recent studies of the influence of cooling rate after the final reaction, we find contradictions to this general rule. The J{sub c} (77 K, 0 T) of so-called {ope… more
Date: November 1, 1994
Creator: Parrell, J. A.; Larbalestier, D. C. & Dorris, S. E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Epitaxial growth of bcc transition metal films and superlattices onto MgO (111), (011) and (001) substrates

Description: We demonstrate epitaxial growth of the bcc transition metals Nb, Mo, Fe, and Cr via sputtering onto single crystal MgO substrates. The epitaxial growth orientations are (011), (112) and (001) when grown onto MgO (111), (011) and (001), respectively. Further we demonstrate that under appropriate growth conditions, superlattices of these materials (e.g., Fe/Cr, Fe/V and Mo/V) can be grown with the same epitaxial order as the films.
Date: April 1, 1994
Creator: Mattson, J. E.; Fullerton, E. E.; Sowers, C. H. & Bader, S. D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Magnetic and structural properties of Fe/Pd multilayers studied by magnetic x-ray dichroism and x-ray absorption spectroscopy

Description: The results of magnetic circular x-ray dichroism (MCXD) measurements and extended x-ray absorption fine structure measurements (EXAFS) of the Fe K-edges of textured Fe(110)/Pd(111) multilayers are reported. The EXAFS results indicates that the iron in the system goes from bcc to a more densely packed system as the thickness of the iron layer is decreased. The magnetic properties were measured by SQUID magnetometry from 5-350 K. For all the samples, the saturation magnetization was significantly… more
Date: December 1, 1994
Creator: Mini, S. M.; Fullerton, E. E.; Sowers, C. H.; Fontaine, A.; Pizzini, S.; Bommannavar, A. S. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Thin film ionic conductors based on cerium oxide

Description: Fluorite and perovskite structure cerium oxide based ceramics are a class of materials that may exhibit good oxygen ion and/or protonic conductivity. The authors have successfully deposited thin films of these materials on a variety of substrates. Interesting orientation relationships were noticed between cerium oxide films and strontium titanate bi-crystal substrates. Near lattice site coincidence theory has been used to study these relationships.
Date: December 1, 1994
Creator: Haridoss, P.; Hellstrom, E.; Garzon, F. H.; Brown, D. R. & Hawley, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Ab Initio Calculations for Dissociative Hydrogen Adsorption on Lithium Oxide Surfaces

Description: Lithium ceramics are one class of materials being considered as tritium breeders for fusion technology,and hydrogen is known to enhance the release of tritium from lithium ceramic materials. Dissociative hydrogen chemisorption on the Li{sub 2}O surfaces of the (100), (110), and (111) planes has been investigated with ab initio Hartree-Fock calculations. Calculations for unrelaxed crystal Li{sub 2}O structures indicated that except for the (100) surface, the (110) and (111) surfaces are stable. … more
Date: December 1, 1994
Creator: Sutjianto, A.; Tam, S. W.; Curtiss, L. A.; Johnson, C. E. & Pandey, R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Vacancy related defects in thin film Pb(ZrTi)O{sub 3} materials

Description: Positron annihilation techniques have been applied to characterize vacancy-related defects in ferroelectric thin film structures. Variable energy positron beam measurements were carried out on doped and undoped Pb(ZrTi)O{sub 3} (PZT) samples subjected to different post-deposition cool down and anneal conditions. The PZT was deposited by sol-gel with either with platinum or RuO{sub 2} electrodes, or by laser ablation with La{sub 0.5}Sr{sub 0.5}CoO{sub 3} electrodes. The RuO{sub 2} and La{sub 0.5… more
Date: December 31, 1994
Creator: Krishnan, A.; Keeble, D. J.; Ramesh, R.; Warren, W. L.; Tuttle, B. A.; Pfeffer, R. L. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Experimental evidence for lattice effects in high temperature superconductors

Description: We present an overview of the experimental evidence for a role of the lattice in the mechanism of high temperature superconductivity. It appears unlikely that a solely conventional electron-phonon interaction produces the pairing. However, there is ample evidence of strong electron and spin to lattice coupling and observations of a response of the lattice to the electronic state. We draw attention to the importance of the local structure in discussions of lattice effects in high-{Tc} supercondu… more
Date: January 18, 1994
Creator: Billinge, S. J. L.; Kwei, G. H. & Thompson, J. D.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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High surface area, high permeability carbon monoliths

Description: The goal of this work is to prepare carbon monoliths having precisely tailored pore size distribution. Prior studies have demonstrated that poly(acrylonitrile) can be processed into a precursor having tailored macropore structure. Since the macropores were preserved during pyrolysis, this synthetic process provided a route to porous carbon having macropores with size =0.1 to 10{mu}m. No micropores of size <2 nm could be detected in the carbon, however, by nitrogen adsorption. In the present wor… more
Date: December 31, 1994
Creator: Lagasse, R. R. & Schroeder, J. L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Density changes in amorphous Pd{sub 80}Si{sub 20} during low temperature ion irradiation

Description: Density changes in amorphous Pd{sub 80}Si{sub 20} during ion irradiation below 100K were detected by in situ HVEM measurements of the changes in specimen length as a function of ion fluence. A decrease in mass density as a function of the ion fluence was observed. The saturation value of the change in mass density was determined to be approximately -1.2%.
Date: November 1, 1994
Creator: Schumacher, G.; Birtcher, R. C. & Rehn, L. E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Manufacturing tailored property ceramic composites

Description: Composite materials are desirable for many advanced engineering applications where the properties of a single phase material cannot meet all of the service requirements; however, existing process technology has limited the development and commercialization of composites. Lack of reproducible sintering to high density is one of the major obstacles to commercializing ceramic composites. Final-stage, non-reactive liquid phase sintering (NLPS) theory provides metrics for sinterability that can be u… more
Date: November 14, 1994
Creator: Ewsuk, K. G. & Harrison, L. W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Electronic structure and pairing of strongly correlated fermions: Fermi liquid versus spin liquid

Description: We summarize recent theoretical results of our group concerning the electronic states of the strongly correlated fermions at nonzero temperature. The state of almost localized fermions is discussed within a mean-field approach for auxiliary bosons, both in the narrow-band (Section 2) and in the hybridized band (Section 3) cases. This state represents a metallic state of correlated fermion systems (such as V{sub 2}O{sub 3}) below the Mott-Hubbard localization threshold. The Fermi liquid state do… more
Date: April 1, 1994
Creator: Byczuk, K.; Karbowski, J.; Spalek, J. & Wojcik, W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The influence of surface structure on the interaction of water with TiO{sub 2}(100)

Description: The influence of surface structure on the interaction of water with TiO{sub 2}(100) (rutile) was investigated. Two unique surface structures of the (100) crystal face can be prepared by oxidation (the bulk-terminated surface) and by vacuum reduction (the (110)- microfaceted surface). Thermal desorption profiles, which measure of the strength of the adsorbate-surface interaction, indicate that submonolayer coverages of water are more stable on the bulk-terminated surface than on the (110)-microf… more
Date: November 1, 1994
Creator: Henderson, M. A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Effect of He pressure on the superconducting transition temperatures of Na{sub 2}CsC{sub 60} and (NH{sub 3}){sub 4}Na{sub 2}CsC{sub 60}

Description: The Na based mixed alkali doped C{sub 60} superconductors show anomalous behavior with respect to the ``universal`` superconducting transition temperature {Tc} vs lattice constant a{sub 0} relation followed by most of the fcc A{sub 3}C{sub 60} superconductors. We have measured dt{sub c}/dP for Na{sub 2}CsC{sub 60} and (NH{sub 3}){sub 4}Na{sub 2}CsC{sub 60} using solid He as the pressure medium to {approximately} 6 kbar finding dT{sub c}/dP equal to {minus}0.8{plus_minus}(0.01) K/kbar and {minus… more
Date: December 31, 1994
Creator: Schirber, J. E.; Bayless, W. R.; Rosseinsky, M. J.; Zhou, O.; Fleming, R. M.; Murphy, D. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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