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in subjects: "360602 -- Other Materials-- Structure & Phase Studies"

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Theory of ordering transformations in metals and minerals

This dissertation presents an investigation of ordering in FCC based systems using the pair potential approximation in the ground state and mean field limits. The theoretical approach is used to explain the occurrence of observed equilibrium phases and characteristics of thermodynamic instabilities, in particular, spinodal ordering and decomposition. It is shown that the stability of non-integer domain sizes in long period superstructures such as Al{sub 3}Ti and Ag{sub 3}Mg may result from the … more

Date: July 1, 1991

Creator: Lindsey, Timothy Francis

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

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Raman microprobe investigation of molecular structure and organization in the native state of woody tissue

Although the primary emphasis of our program has remained with the application of Raman spectroscopy to the study of native tissue, the scope of the work has been expanded to include a number of complementary approaches. These have included Solid State 13C NMR, autoradiography of radiolabeled woody tissue sections, and the generation of biomimetic tertiary aggregates which simulate states of aggregation characteristic of cell walls. Our Raman spectroscopic studies have resulted in progress in t… more

Date: August 1, 1989

Creator: Atalla, R.H.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Fabrication and characterization of MCC approved testing material: ATM-11 glass

ATM-11 glass is designed to be representative of defense high-level waste glasses that will be produced by the Defense Waste Processing Facility at the Savannah River Plant in Aiken, South Carolina. It is representative of a 300-year-old nuclear waste glass and was intended as a conservative compromise between 10-year-old waste and 1000-year-old waste. The feedstock material for this glass was supplied by Savannah River Laboratory, Aiken, SC, as SRL-165 black frit to which was added Ba, Cs, Mo,… more

Date: August 1, 1986

Creator: Wald, J. W. & Daniel, J. L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Neutron scattering experiments on well-staged graphite - FeCl/sub 3/

This paper reports results of a neutron diffraction study on both the magnetic and the lattice dynamic structure of graphite-FeCl/sub 3/. The FeCl/sub 3/ system was selected for this study because of the interesting magnetic properties previously reported for this system. Of particular interest is the low temperature magnetic phase transition, which has been shown to be stage dependent. Special emphasis was given to the study of the low temperature magnetic state of the Fe/sup 3 +/ spins and to… more

Date: January 1, 1981

Creator: Axe, J.D.; Majkrzak, C.F.; Passell, L.; Satija, S.K.; Dresselhaus, G. & Mazurek, H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Flexibility in formulating and processing SYNROC D: a current assessment

In a recent series of papers, the authors have addressed the formulation, preparation, characterization and performance testing of SYNROC containing SRP defense wastes. They have also recently published a brief description of the SYNROC process flow sheets and a schematic layout of an associate processing facility. In this brief paper they summarize current data and discuss the implications of: (1) the flexibility of the SYNROC formulation to accommodate unanticipated changes in feed compositio… more

Date: March 1, 1982

Creator: Campbell, J. H.; Ryerson, F. J.; Rozsa, R. B. & Hoenig, C. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Consolidated waste forms: glass marbles and ceramic pellets

Glass marbles and ceramic pellets have been developed at Pacific Northwest Laboratory as part of the multibarrier concept for immobilizing high-level radioactive waste. These consolidated waste forms served as substrates for the application of various inert coatings and as ideal-sized particles for encapsulation in protective matrices. Marble and pellet formulations were based on existing defense wastes at Savannah River Plant and proposed commercial wastes. To produce marbles, glass is poured … more

Date: May 1, 1982

Creator: Treat, R.L. & Rusin, J.M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Coupled electron-nuclear magnetism and neutron diffraction. [PrSn/sub 3/; HoVO/sub 4/; PrCu/sub 2/]

It often occurs that, in a rare-earth compound having a singlet electronic ground state, a long-range magnetically ordered state is formed by coupling of the nuclear spins with the electrons through the hyperfine interaction, at millikelvin temperatures. Neutron scattering has been used to measure the details of the magnetization processes of both the electrons and the nuclear spins in the coupled state in PrSn/sub 3/, HoVO/sub 4/, and PrCu/sub 2/. The polarized nuclear spins could be observed … more

Date: July 1, 1985

Creator: Kawarazaki, S. & Arthur, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Studies of the phase transitions in UAs with neutron scattering

Uranium arsenide is known to order with the type-I antiferromagnetic (AF) structure at approx. 126 K, and exhibit a first-order transition to the type-IA AF structure at T/sub N//2. We have now reexamined these transitions with a single crystal. Above T/sub N/ UAs exhibits critical scattering suggesting a tendency to order with an incommensurate wavevector, but then suddenly orders with the AF-I structure. The analysis of the data shows the need to consider anisotropic exchange interactions of … more

Date: January 1, 1980

Creator: Sinha, S.K.; Lander, G.H.; Shapiro, S.M. & Vogt, O.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Thin film cadmium telluride, zinc telluride, and mercury zinc telluride solar cells

This report describes research to demonstrate (1) thin film cadmium telluride solar cells with a quantum efficiency of 75% or higher at 0. 44 {mu}m and a photovoltaic efficiency of 11.5% or greater, and (2) thin film zinc telluride and mercury zinc telluride solar cells with a transparency to sub-band-gap radiation of 65% and a photovoltaic conversion efficiency of 5% and 8%, respectively. Work was directed at (1) depositing transparent conducting semiconductor films by solution growth and meta… more

Date: April 1, 1992

Creator: Chu, T.L. (University of South Florida, Tampa, FL (United States))

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Thermal history and crystallization characteristics of the DWPF glass waste form

The Defense Waste Processing Facility (DWPF) at the Savannah River Site will immobilize high-level radioactive waste by incorporating it in a stable borosilicate glass waste form suitable for long term storage in a geologic repository. The thermal history of the canistered waste form to be produced in DWPF was determined during filling and subsequent cooldown operations by simulating DWPF production conditions. Samples of simulated waste glass of projected compositions for the DWPF have been ex… more

Date: January 1, 1992

Creator: Marra, S. L.; Edwards, R. E. & Jantzen, Carol M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Catalyst dispersion and activity under conditions of temperature- staged liquefaction

The general objectives of this research are (1) to investigate the use of highly dispersed catalysts for the pretreatment of coal by mild hydrogenation, (2) to identify the active forms of the catalysts under reaction conditions and (3) to clarify the mechanisms of catalysis. The ultimate objective is to ascertain if mild catalytic hydrogenation resulting in very limited or no coal solubilization is an advantageous pretreatment for the transformation of coal into transportable fuels. The experi… more

Date: September 1, 1991

Creator: Davis, A.; Schobert, H.H.; Mitchell, G.D. & Artok, L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Phase formation in the Pt/InP thin film system

InP substrates with 40nm metal films of Pt were encapsulated in SiO{sub 2}, and isochronally annealed up to 600{degrees}C in flowing forming gas. The composition and morphology of the phases that formed were studied using x-ray diffraction, Rutherford Backscattering, and transmission electron microscopy. Results show that the Pt/InP system begins interacting at 300{degrees}C. TEM analysis of the 350{degrees}C anneal shows unreacted Pt and additional polycrystalline phases, with no observed orie… more

Date: April 1, 1989

Creator: Olson, D.A.; Yu, K.M.; Washburn, J. (Lawrence Berkeley Lab., CA (United States)) & Sands, T. (Bellcore, Red Bank, NJ (United States))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Some reduced ternary and quaternary oxides of molybdenum containing strong metal-metal bonds. [Molybdates of ScZn, LiZn, Zn, Ba, and Na]

ScZnMo/sub 3/O/sub 8/, LiZn/sub 2/Mo/sub 3/O/sub 8/, and Zn/sub 3/Mo/sub 3/O/sub 8/ were synthesized and crystal structures were determined for the latter two. These oxides contain the same type of triangular molybdenum atom clusters found in Zn/sub 2/Mo/sub 3/O/sub 8/, but each of the trimeric clusters has available one or two additional electrons for participation in metal-metal bonding. Another new ternary oxide containing discrete metal atom clusters is Ba/sub 1/ /sub 14/Mo/sub 8/O/sub 16/.… more

Date: October 1, 1981

Creator: Torardi, C.C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Density separation of boron particles. Final report

A density distribution much broader than expected was observed in lots of natural boron powder supplied by two different sources. The material in both lots was found to have a rhombohedral crystal structure, and the only other parameters which seemed to account for such a distribution were impurities within the crystal structure and varying isotopic ratios. A separation technique was established to isolate boron particles in narrow densty ranges. The isolated fractions were subsequently analyze… more

Date: April 1, 1980

Creator: Smith, R. M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Physical and chemical properties of the products of in situ vitrification engineering tests 5, 6, and 7

In situ vitrification (ISV) is an in situ thermal treatment process that is being investigated by the Idaho National Engineering Laboratory (INEL) for application to buried waste sites. ISV is a thermal treatment process that converts contaminated soil into a chemically inert and stable glass and crystalline product. The INEL is evaluating whether the treatment process is a viable one for remediating a buried mixed transuranic waste site at the INEL Subsurface Disposal Area (SDA). The SDA is a … more

Date: December 1, 1991

Creator: Loehr, C. A. & Weidner, J. R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Infrared and Raman investigation of rare-earth phosphate glasses for potential use as radioactive waste forms

This project was designed to investigate the properties of the rare-earth phosphate glasses CeO{sub 2}-P{sub 2}O{sub 5} and Pr{sub 2}O{sub 3}-P{sub 2}O{sub 5} for potential use as radioactive waste glasses. The research involved determination of the glass-forming region, loading capacity, and optimum processing parameters of the glasses. Structural studies of the unloaded host glasses and glasses loaded with simulated waste elements were to be done using Raman, infrared and infrared reflection … more

Date: November 10, 1986

Creator: Morgan, S.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Profiling and Mapping of Advanced Materials Using Spatially Resolved Raman Spectroscopy

We have developed a technique to profile important physical and chemical properties of materials based upon simultaneous acquisition of Raman spectra along a laser illumination line, coupled with extensive and rapid spectral analysis to extract the desired information. The technique uses a two-dimensional spectroscopic detector and, in contrast to Hadamard techniques, sample movement in one dimension that allows all collected light to be detected. Property maps comprised of the analysis results… more

Date: August 1, 1991

Creator: Ager, Joel; Veirs, D. K.; Lee, H. Q. & Rosenblatt, G. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Neutron scattering methods for materials science

This article describes some of the neutron scattering techniques which can be used to probe structures of materials on length scales which range from less than 1 {Angstrom} to 1 {mu}m. The intent is to remove the veils of secrecy and mystery which have apparently prevented the wide application of these techniques to problems in materials science. 28 refs., 5 figs.

Date: January 1, 1989

Creator: Pynn, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Sentinel gap basalt reacted in a temperature gradient

Six Basalt prisms were reacted in a controlled temperature gradient hydrothermal circulation system for two months. The prisms are centered at 72, 119, 161, 209, 270, and 310/sup 0/C. Total pressure is 1/3 kbar. All prisms show large weight loss: 5.5% to 14.9%. The matrix micropegmatite and natural nontronitic alteration readily react to clays at all temperatures. The first four prisms are coated with a Ca-smectite while the last two prisms are covered with discrete patches of K rich phengite a… more

Date: January 1, 1982

Creator: Charles, R. W. & Bayhurst, Gregory K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Ultrasonic beam distortion in transversely isotropic media

The distortion of beam profiles and skewing of beam energy observed in transmission of ultrasound into a transversely isotropic medium can lead to erroneous interpretations of NDE data for materials such as columnar-grain steels and fiber-reinforced composites. In this paper, results are presentd for the numerical evaluation of the exact Fourier integral representation of transmission of an arbitrary incident field from an isotropic into a transversely isotropic half-space. The problem is fully… more

Date: August 1, 1987

Creator: Roberts, R. A. & Kupperman, D. S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Self-diffusion of calcium and yttrium in pure and YF/sub 3/-doped CaF/sub 2/ single crystals

Self-diffusion coefficients for Ca and Y were measured in pure and YF/sub 3/-doped CaF/sub 2/ crystals for dopant levels ranging from 2 to 10 mole %. Diffusion data were analyzed as a function of temperature and as a function of composition. Comparison of Arrhenius relationships for both Ca and Y showed that the activation energy for cation diffusion decreased approximately linearly as the YF/sub 3/ dopant level increased. Atomic jump pathways were considered and the decrease in the activation … more

Date: July 1, 1979

Creator: Kucheria, C.S.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Model of the recrystallization mechanism of amorphous silicon layers created by ion implantation

The recrystallization behavior during annealing of thin films of amorphous (..cap alpha..) silicon, in contact with a single crystal silicon substrate (referred to as C), has been studied in the transmission electron microscope (TEM). The amorphous film is created during high dose phosphorus ion implantation at 100 keV. It was found that the crystal substrate orientation and the implantation temperature have dramatic effects on the recrystallizaton rate, and the defect microstructure produced d… more

Date: November 1, 1979

Creator: Drosd, R.M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Recent results on the effect of gamma radiation on the durability and microstructure of DWPF glass

The effect of gamma radiation on the durability and microstructure of a simulated nuclear waste glass from the Savannah River Site has been carefully investigated. Three large pieces of glass were irradiated with a Co-60 source to three doses up to a maximum dose of 3.1 {times} 10{sup 10} rad. Internal samples of the large pieces of irradiated and unirradiated glass were leached in deionized water to investigate durability changes and were examined by transmission electron microscopy (TEM) to i… more

Date: January 1, 1989

Creator: Bibler, N. E.; Tosten, M. H. & Beam, D. C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Fabrication and characterization of MCC approved testing material: ATM-9 glass

The Materials Characterization Center ATM-9 glass is designed to be representative of glass to be produced by the Defense Waste Processing Facility at the Savannah River Plant, Aiken, South Carolina. ATM-9 glass contains all of the major components of the DWPF glass and corresponds to a waste loading of 29 wt %. The feedstock material for this glass was supplied by Savannah River Laboratory, Aiken, SC, as SRL-165 Black Frit to which was added Ba, Cs, Md, Nd, Zr, as well as /sup 99/Tc, depleted … more

Date: June 1, 1986

Creator: Wald, J.W.

Item Type: Report

Partner: UNT Libraries Government Documents Department