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in subjects: "Magnesium Oxides"

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Hot isostatically-pressed aluminosilicate glass-ceramic with natural crystalline analogues for immobilizing the calcined high-level nuclear waste at the Idaho Chemical Processing Plant

The additives Si, Al, MgO, P{sub 2}O{sub 5} were mechanically blended with fluorinelsodium calcine in varying proportions. The batches were vacuum sealed in stainless steel canisters and hot isostatically pressed at 20,000 PSI and 1000 C for 4 hours. The resulting suite of glass-ceramic waste forms parallels the natural rocks in microstructural and compositional heterogeneity. Several crystalline phases ar analogous in composition and structure to naturally occurring minerals. Additional crysta… more

Date: December 1, 1993

Creator: Raman, S.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

High angular resolution measurements of K shell x-ray emission created by electron channeling in the analytical electron microscope.

Since the original observations by Duncumb in 1962, a number of studies have been conducted on the effects of electron channel on characteristic x-ray emission and microanalysis. Most of the recent studies have concentrated upon using the phenomenon to perform site specific distributions of impurity elements in ordered compounds using the ALCHEMI methodology. Very few studies have attempted to accurately measure the effect as a function of orientation and compare these results to theories. In t… more

Date: March 10, 1999

Creator: Zaluzec, N. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Magnetic anisotropy and its microstructural origin in epitaxially grown SmCo thin films.

Microstructural features and magnetic behavior of epitaxially grown SmCo thin films with very high in-plane anisotropy are presented. Transmission electron microscopy was used to characterize the microstructure while magnetic measurements were performed using dc and SQUID magnetometers. Two substrate orientations were studied, i.e., MgO(100)/Cr(100)/SmCo(11{bar 2}0) and MgO(110)/Cr(211)/SmCo(1{bar 1}00). In the former, the SmCo(11{bar 2}0) film shows a bicrystalline microstructure, whereas in t… more

Date: April 15, 1998

Creator: Benaissa, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Electrochemical studies of Mg-doped Li{sub 4}Ti{sub 5}O{sub 12} anodes.

Commercial lithium-ion batteries use carbon as the material of choice for the anode. However, because lithiated carbon has a voltage very close to the potential of metallic lithium, there are concerns about the safety of fully-charged carbon electrodes. The safety issue can be addressed by using a material that intercalates lithium at a higher voltage. A promising material is the lithium-titanium-oxide spinel material Li{sub 4}Ti{sub 5}O{sub 12} which can accommodate 3 Li{sup +} ions per formul… more

Date: July 19, 1999

Creator: Chen, C. H.; Jansen, A. N. & Vaughey, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Conversion of light hydrocarbon gases to metal carbides for production of liquid fuels and chemicals. Quarterly technical status report, April 1, 1995--June 30, 1995

Upgrading of the experimental apparatus was necessitated by problems encountered in the previous scoping runs with CH{sub 4}/MgO. To further improve plasma stability, a pressure controller was installed on the cooling chamber to maintain the chamber pressure constant at 1 atm and a mass flow controller was installed on the main plasma gas inlet line. With a fully functional data acquisition and control system, there is now the capability to record arc voltage, arc current, chamber pressure, fee… more

Date: August 1, 1995

Creator: Diaz, A. F.; Modestino, A. J. & Howard, J. B.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Magnetic properties of epitaxial and polycrystalline Fe/Si multilayers

Fe/Si multilayers with antiferromagnetic interlayer coupling have been grown via ion-beam sputtering on both glass and single-crystal substrates. X-ray diffraction measurements show that both sets of films have crystalline iron silicide spacer layers and a periodic composition modulation. Films grown on glass have smaller crystallite sizes than those grown on single-crystal substrates and have a significant remanent magnetization. Films grown on single-crystal substrates have a smaller remanenc… more

Date: August 1, 1995

Creator: Chaiken, A.; Michel, R.P. & Wang, C.T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Development of Biaxially Textured YBa{sub 2}Cu{sub 3}O{sub 7} Coated Conductors in the U.S.

Two new processes have been under development since 1991 that promise a new, cost-effective way to manufacture flexible, high current density wires made from YBa{sub 2}Cu{sub 3}O{sub 7} (YBCO). The key is to prepare a textured substrate, or ''template,'' on which the YBCO may be deposited as a biaxially aligned thick film. Ion beam assisted deposition (IBAD) of yttria stabilized zirconia or magnesium oxide on alloy tapes enables a final superconducting layer with grain-to-grain, in-plane alignm… more

Date: November 13, 1999

Creator: Christen, D.K.; Hawsey, R.A. & Kroeger, D.M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Enhancement of methane conversion using electric fields. Quarterly report, December 1994--March 1995

The goal of this project is the development of novel, economical, processes for the conversion of natural gas to more valuable projects such as methanol, ethylene and other organic oxygenates or higher hydrocarbons. The methodologies of the project are to investigate and develop low temperature electric discharges and electric field-enhanced catalysis for carrying out these conversions. In the case of low temperature discharges, the conversion is carried out at ambient temperature which in effe… more

Date: April 1, 1995

Creator: Mallinson, Richard G. & Lobban, Lance L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Structural stability of LiMn{sub 2}O{sub 4} electrodes for lithium batteries

the structural stability of LiMn{sub 2}O{sub 4}, which is of interest as an insertion electrode for rechargeable lithium batteries, is discussed with respect to processing techniques, composition, the Li- Mn-O phase diagram, and electrochemical behavior. Particular attention is paid to processing conditions that result in the formation of lithium-magnesium-oxide spinel products in which Mn{sup 2+} ions partially occupy the tetrahedral sites of the spinel structure. The electrochemical behavior … more

Date: April 1, 1996

Creator: Thackeray, M.M.; Mansuetto, M.F. & Bates, J.B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Effect of composition on the processing and properties of sintered reaction-bonded silicon nitride

The type of silicon powder and sintering additive were found to influence the processing and final mechanical properties of sintered reaction bonded silicon nitride. High purity silicon powders produced low {alpha}-Si{sub 3}N{sub 4} content during nitridation. The Si powder type had no apparent effect on densification. More complete nitridation and higher room temperature mechanical properties were observed for the Si powders with higher Fe contents. However, the higher Fe contents resulted in … more

Date: April 1, 1996

Creator: Tiegs, T. N.; Kiggans, J. O.; Montgomery, F. C.; Lin, H. T.; Barker, D. L.; Snodgrass, J. D. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Defects and their origin in thin films of (001) alkaline earth oxides

MgO is used as an optical isolation layer for waveguides epitaxially grown on Si. Crystalline perfection of MgO is critical because it serves as a substrate for the single crytal, perovskite guiding layer. Imperfections in the MgO will result in imperfections in the guiding layer and lead to large optical losses for the planar waveguide structure. It is shown that the most common defect to form in thin MgO films are twin boundaries between {l_brace}111{r_brace}-type planes. Highest density of t… more

Date: December 31, 1995

Creator: Walker, F.J.; McKee, R.A.; Pennycook, S.J. & Thundat, T.G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A comparative study of radiation damage in Al{sub 2}O{sub 3}, FeTiO{sub 3}, and MgTiO{sub 3}

Oriented single crystals of synthetic alpha-alumina ({alpha}-Al{sub 2}O{sub 3}), geikielite (MgTiO{sub 3}) natural ilmenite (FeTiO{sub 3}) were irradiated with 200 keV argon ions under cryogenic conditions (100 K) to assess their damage response. Using Rutherford backscattering spectrometry combined with ion channeling techniques, it was found that ilmenite amorphized readily at doses below 5{times}10{sup 14}, alumina amorphized at a dose of 1-2{times}{sup 15}, and geikielite was amorphized at … more

Date: December 31, 1995

Creator: Mitchell, J. N.; Yu, Ning; Sickafus, K. E.; Nastasi, M.; Taylor, T. N.; McClellan, K. J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Predicting primary crystalline phase and liquidus temperature above or below 1050{degrees}C as functions of glass composition

This report presents the results of applying statistical empirical modeling techniques to primary crystalline phase at the liquidus temperature (T{sub L}) and (ii) whether liquidus temperature is above or below 1050{degree}C (1OO{degree}C below a melting temperature of 1150{degree}C). Data used in modeling primary crystalline phase and liquidus temperate are from the Composition Variability Study (CVS) of Hanford waste glass compositions and properties. The majority of the 123 CVS glasses are c… more

Date: February 1, 1996

Creator: Redgate, P. E. & Piepel, G. F.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Ion beam-induced changes in optical properties of MgO

The implantation of Ag into MgO (100) single crystals, followed by thermal annealing at 1,100 C, leads to dramatic changes in their optical properties. The changes in the optical properties are due to the presence of small Ag clusters which are formed in the annealed samples. The small Ag clusters are obtained by thermal annealing of the implanted MgO crystals between 600 C and 1,100 C to investigate the changes in cluster sizes and to correlate with changes in their optical properties. Sample … more

Date: December 31, 1995

Creator: Qian, Y.; Ila, D.; He, K. X.; Curley, M.; Poker, D. B. & Boatner, L. A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Tribological properties of hard carbon films on zirconia ceramics

This study investigated the tribological properties of hard diamondlike carbon (DLC) films on magnesia-partially-stabilized zirconia (MgO-PSZ) substrates over a wide range of loads, speeds, temperatures, and counterface materials. The films were 2 {micro}m-thick and produced on by ion-beam deposition at room temperature. Tribological tests were conducted on a ball-on-disk machine in open air of 30 to 50% relative humidity under contact loads of 1 to 50 N, at sliding velocities of 0.1 to 6 m/s, … more

Date: December 31, 1995

Creator: Erdemir, A.; Bindal, C.; Fenske, G.R. & Wilbur, P.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Glass formulation for phase 1 high-level waste vitrification

The purpose of this study is to provide potential glass formulations for prospective Phase 1 High-Level Waste (HLW) vitrification at Hanford. The results reported here will be used to aid in developing a Phase 1 HLW vitrification request for proposal (RFP) and facilitate the evaluation of ensuing proposals. The following factors were considered in the glass formulation effort: impact on total glass volume of requiring the vendor to process each of the tank compositions independently versus as a… more

Date: April 1996

Creator: Vienna, J. D. & Hrma, P. R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Conversion of light hydrocarbon gases to metal carbides for production of liquid fuels and chemicals. Quarterly technical status report, July 1, 1995--September 30, 1995

Two final scoping runs were conducted to test the experimental protocol for methane conversion to alkaline earth metal carbides in the thermal plasma reactor and to refine the techniques for carbide analysis. Having demonstrated the adequacy of the experimental protocol, the systematic study of metal carbide synthesis from methane and MgO commenced. Initial runs with MgO/CH{sub 4} gave surprisingly low methane conversions (<2%) to magnesium carbides, despite high conversions (65-90%) to hydroge… more

Date: November 1, 1995

Creator: Diaz, A. F.; Modestino, A. J. & Howard, J. B.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Selective methane oxidation over promoted oxide catalysts. Quarterly report, September--November, 1994

Experimental research in the direct conversion of methane to methanol using a double bed reactor and with gaseous steam as cofeed with the CH{sub 4}/air reactant mixture continued during this quarter in order to improve the methanol space time yield. Work was carried out along several pathways that included a stability test of the second bed catalyst 1%V{sub 2}O{sub 5}/SiO{sub 2} that yielded up to 100 g methanol/kg cat/hr and investigation of the effect of pressure on methanol yields. Redox do… more

Date: December 1, 1994

Creator: Klier, Kamil; Herman, Richard G.; Shi, Chunlei; Wang, Chuan-Bao & Sun, Qun

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

X-ray diffraction characterization of thin superconductive films

The physical and mechanical properties of thin films are often different from the properties of bulk material and are dictated by the film/substrate orientation relationship, crystal anisotropy and crystalgraphic texture of the film. X-ray diffraction texture analysis provides information about preferential film growth and can be used for optimization of deposition parameters and prediction of properties of thin films. An x-ray back reflection technique using the Braga-Brentano geometry with ex… more

Date: December 31, 1995

Creator: Kozaczek, K. J.; Book, G. W.; Watkins, T. R. & Carter, W. B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Influence of irradiation spectrum and implanted ions on the amorphization of ceramics

Polycrystalline Al2O3, magnesium aluminate spinel (MgAl2O4), MgO, Si3N4, and SiC were irradiated with various ions at 200-450 K, and microstructures were examined following irradiation using cross-section TEM. Amorphization was not observed in any of the irradiated oxide ceramics, despsite damage energy densities up to {similar_to}7 keV/atom (70 displacements per atom). On the other hand, SiC readily amorphized after damage levels of {similar_to}0.4 dpa at room temperature (RT). Si3N4 exhibited… more

Date: December 31, 1995

Creator: Zinkle, S. J. & Snead, L. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Effects of aqueous environment on long-term durability of phosphate-bonded ceramic waste forms

Over the last few years, Argonne National Laboratory has been developing room-temperature-setting chemically-bonded phosphate ceramics for solidifying and stabilizing low-level mixed wastes. This technology is crucial for stabilizing waste streams that contain volatile species and off-gas secondary waste streams generated by high-temperature treatment of such wastes. Magnesium phosphate ceramic has been developed to treat mixed wastes such as ash, salts, and cement sludges. Waste forms of surro… more

Date: March 1, 1996

Creator: Singh, D.; Wagh, A.S. & Jeong, S.Y.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Thin-film perovskites-ferroelectric materials for integrated optics

Optical guided wave (OGW) devices, based on LiNbO{sub 3} or GaAs. are commercially available products with established markets and applications. While LiNbO{sub 3} presently dominates the commercial applications, there are several drivers for the development of improved electro-optic (EO) materials. If the appropriate crystal quality could be obtained for thin-film BaTiO{sub 3} supported on MgO for example, or for an integrated BaTiO{sub 3}/Mg0 structure on silicon or GaAs, then the optimum OGW… more

Date: December 31, 1995

Creator: Walker, F. J. & McKee, R. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Can the multianvil apparatus really be used for high-pressure deformation experiments?

Past claims of the suitability of the MA-8 multianvil press as a deformation apparatus may have been overstated. On the basis of measurements of final octahedron size and of guide block displacement as a function of time, using the 10/5, 14/8, and 18/11 assemblies (octahedron edge length in mm/truncation edge length in mm) with MgO octahedra and pyrophyllite gasketing, it appears that at run conditions of interest to most researchers there is no appreciable time-dependent creep of gaskets and o… more

Date: April 24, 1996

Creator: Durham, W.B. & Rubie, D.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Metal-ceramic composites for hostile environment applications

The authors have developed a new metal-ceramic composite made from vanadium metal (V) and a non-stoichiometric magnesio-aluminate spinel ceramic. Three vanadium-spinel compositions, 40-60, 50-50, and 60-40 (by volume) were prepared by hot pressing mixtures of commercial powders. The properties of these composites were determined by measuring coefficient of thermal expansion, hardness, elastic constants, and fracture toughness. Radiation damage studies were performed on 50-50 vanadium-spinel com… more

Date: July 1, 1996

Creator: Uestuendag, E.; Sickafus, K.; He, Y.; Schwarz, R. B.; Panda, P. C. & Raj, R.

Item Type: Report

Partner: UNT Libraries Government Documents Department