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in subjects: "Barium Compounds"

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Array automated assembly: Phase 2. Quarterly report

An analysis was made of cost trade-offs for shaping modified square wafers from cylindrical crystals. For reasonably expectable silicon and sheet costs, the optimum shape will be nearer a circle than a square. Tests were conducted of the effectiveness of texture etching for removal of surface damage on sawed wafers. Four glass systems have survived preliminary screening tests for use as edge masking dielectrics. These include beta-spodumen, MgO-Al/sub 2/O/sub 3/ borosilicate, baria and titania … more

Date: February 1, 1978

Creator: Taylor, W.E.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Radicals in Irradiated Crystals Studied by ESR Spectroscopy. Technical Report, January 1--December 31, 1967

No Description Available.

Date: August 31, 1968

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Theoretical modeling and experimental characterization of planar defects in Y sub 2 Ba sub 4 Cu sub 6+x O sub 14+x

Crystallographic defects and phase transformations in the system Y{sub 2}Ba{sub 4}Cu{sub 6 + x}O{sub 14 + x}(0{le}{times}{le}4) are investigated by high resolution transmission electron microscopy (TEM) and static lattice, three dimensional Monte Carlo computer simulations. High resolution images of partially transformed (x = 2 to x = 1) material reveal a prevalence of CuO planar defects (stacking faults) associated with the transformation and an absence of disturbance to the perovskite Ba-Y-Ba… more

Date: November 1, 1990

Creator: Burmester, C. P.; Fendorf, M.; Gronsky, R. & Wille, L. T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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The use of BaF sub 2 buffer layers for the sputter-deposition of TlCaBaCuO thin-film superconductors

Thin films of the Tl-based superconductors often have relatively poor properties because of film/substrate interdiffusion which occurs during the anneal. We have therefore investigated the use of BaF{sub 2} as a diffusion barrier. TlCaBaCuO thin films were deposited by dc magnetron sputtering onto MgO <100> substrates, both with and without an evaporation-deposited BaF{sub 2} buffer layer, and post-annealed in a Tl over-pressure. Electrical properties of the films were determined by four-point … more

Date: January 1, 1989

Creator: Hubbard, K. M.; Arendt, P. N.; Brown, D. R.; Cooke, D. W.; Elliott, N. E.; Farr, J. D. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Laser deposition and laser modification of high-temperature superconducting thin films

Applications of high-temperature superconductors (HTSC) may require epitaxial films with {Tc}{ge}77 K, and J{sub c}{ge}10{sup 6} A/cm{sup 2}. In situ pulsed laser deposition (PLD) is suitable for fabrication of such films. We report parametric studies on the effect of laser and processing parameters on the crystallinity, epitaxy and electrical properties of laser-deposited HTSC thin films. In addition, several laser-based processes were used to modify the electrical properties ({Tc} and J{sub c… more

Date: January 1, 1991

Creator: Dye, R. C.; Foltyn, S. R.; Nogar, N. S.; Wu, X. D.; Peterson, E. J. & Muenchausen, R. E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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The influence of anharmonic phonons on the isotope effect in high- Tc oxides

Anharmonic phonons are examined to study the unusual isotope effect exponents for the high-{Tc} oxides. Within a simple model of anharmonicity, the mass dependences of the electron-phonon coupling constant {lambda} and the phonon frequency determine the isotope effect exponent {alpha} as a function of coupling strength. A model in which the outer wells of a multiple-well potential deepen as the orthorhombic/low temperature tetragonal phase transition in La{sub 2-x}M{sub x}CuO{sub 4} is approach… more

Date: January 1, 1992

Creator: Crespi, V.H. & Cohen, M.L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Recent advances in high-temperature superconductor wire fabrication and applications development

In this paper, recent advances in fabrication of HTS wires are summarized, and detailed discussion is provided for developments in near- and intermediate-term applications. Near-term applications, using presently obtainable current densities, include: liquid-nitrogen depth sensors, cryostat current leads, and magnetic bearings. Intermediate-term applications, using current densities expected to be available in the near future include fault-current limiters and short transmission lines. 25 refs.

Date: January 1, 1992

Creator: Hull, J.R. & Uherka, K.L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Electron irradiation effects in YBa/sub 2/Cu/sub 3/O/sub 7-delta/ single crystals

Defect structures in YBa/sub 2/Cu/sub 3/O/sub 7/minus/delta/ produced by electron irradiation at 300/degree/K, were investigated by transmission electron microscopy. Threshold energies for the production of visible defects were determined to b 152 keV and 131 keV (+- 7 keV) in directions near the a- and b-axes, respectively (b > a, both perpendicular to c, the long axis in the orthorhombic structure). During above-threshold irradiations in an electron flux of 3 x 10 /sup 18/ cm/sup /minus/2/s/s… more

Date: April 1, 1988

Creator: Kirk, M.A.; Baker, M.C.; Liu, J.Z.; Lam, D.J. & Weber, H.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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New developments in optical phase conjugation

In this review two major areas of investigation in optical phase conjugation are discussed: stimulated Brillouin scattering and dynamic effects in photorefractive media. 5 refs., 10 figs.

Date: January 1, 1986

Creator: Bigio, I. J.; Fisher, R. A.; Gosnell, T. R.; Kurnit, N. A.; Loree, T. R.; Moore, T. R. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Barium silicate glass/Inconel X-750 interaction. [PWR]

Water reactor safety programs at the Idaho National Engineering Laboratory have required the development of specialized instrumentation. An example is the electrical conductivity-sensitive liquid level transducer developed for use in pressurized-water reactors (PWRs) in which the operation of the sensing probe relies upon the passage of current through the water between the center pin of the electrode and its shell such that when water is present the resulting voltage is low, and conversely, wh… more

Date: January 1, 1980

Creator: Kelsey, P.V. Jr.; Siegel, W.T. & Miley, D.V.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Preparation of oxide superconductors

Preparation of bulk superconductors by cold pressing and sintering of metal oxides has been optimized in this study. A knowledge of phase behavior was used in developing a flux method for growing superconducting single crystals of yttrium and gadolinium based superconductors. Means of achieving single-phase, high-density samples of (Rare Earth)-Ba/sub 2/Cu/sub 3/O/sub 7/ with optimal electronic properties are reviewed. 2 refs., 2 figs.

Date: January 1, 1988

Creator: Peterson, D.E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Energetics and statistics of order in alloys with application to oxide superconductors

Now that first-principles calculations of ordering transformations are becoming increasingly accurate, the deficiencies of earlier mean field methods are becoming increasingly apparent. New techniques, based on cluster expansions, are now alleviating many of the earlier problems and are producing very satisfactory results. These ideas will be illustrated for the case of oxygen ordering in the YBa{sub 2}Cu{sub 3}O{sub z} superconducting compound, for which a very simple two-dimensional Ising mod… more

Date: June 1, 1991

Creator: de Fontaine, D. (Lawrence Livermore National Lab., CA (United States) California Univ., Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering); Ceder, G. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Materials Science and Engineering) & Asta, M. (Lawrence Livermore National Lab., CA (United States) California Univ., Berkeley, CA (United States).

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Study of selected off-gases produced during the immobilization of nuclear wastes in the SYNROC process. Final report for year ended December 31, 1981. [Pollucite, CsAlSi/sub 2/O/sub 6/, and barium-cesium hollandite, (Ba,Cs)Al/sub 2/Ti/sub 6/O/sub 16/]

Calculation of possible off-gases expected during the fabrication of SYNROC showed that volatilization of cesium would be a significant problem. Samples of the cesium containing minerals pollucite, CsAlSi/sub 2/O/sub 6/, and barium-cesium hollandite, (Ba,Cs)Al/sub 2/Ti/sub 6/O/sub 16/, were prepared for vaporization studies. Fifteen vaporization runs were made with the hollandite samples. With dry air as the carrier gas, the vapor pressure of cesium over Ba/sub 0/ /sub 8/Cs/sub 0/ /sub 4/Al/sub… more

Date: December 31, 1981

Creator: Carpenter, J.H.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Positron lifetimes in solids from first principles calculations

We present a first principles method for calculating positron lifetimes in solids, based on self-consistent calculations using the Linear Muffin-Tin Orbital method. Local density approximations are used for both electron-electron and electron-positron interactions. Results are presented for a variety of elemental metals and vacancies to demonstrate the reliability of this approach. Theoretical calculations of positron lifetimes can be used to interpret experimental data. As an examples of this,… more

Date: August 7, 1991

Creator: Sterne, P. A.; O'Brien, J. C.; Howell, R. H. & Kaiser, J. H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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YBa sub 2 Cu sub (3-x) Co sub x O sub y : A substrate material for YBCO superconductors

The physical properties of the ceramic YBa{sub 2}Cu{sub (3-x)}Co{sub x}O{sub y} have been investigated in order to evaluate its usefulness as a substrate material for YBCO superconductors. YBa{sub 2}Cu{sub (3-x)}Co{sub x}O{sub y} has been found to be thermally and chemically compatible with 123 and displays adequate electrical properties for a substrate material. A material with the nominal composition of YBa{sub 2}Cu{sub 2.2}Co{sub 0.8}O{sub 7} was investigated, extensively. The mechanical pro… more

Date: April 1, 1992

Creator: Vienna, J.D.; Balachandran, U.; Poeppel, R.B. (Argonne National Lab., IL (United States)); Cermignani, W. & Taylor, J.A. (State Univ. of New York, Alfred, NY (United States). Coll. of Ceramics)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Auger decay mechanism in photon-stimulated desorption of ions from surfaces

Photon-stimulated desorption (PSD) of positive ions was studied with synchrotron radiation using an angle-integrating time-of-flight mass spectrometer. Ion yields as functions of photon energy near core levels were measured from condensed gases, alkali fluorides, and other alkali and alkaline earth halides. These results are compared to bulk photoabsorption measurements with emphasis on understanding fundamental desorption mechanisms. The applicability of the Auger decay mechanism, in which ion… more

Date: November 1, 1983

Creator: Parks, C.C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Neutron scattering from the flux lattice in high temperature superconductors

Neutron scattering has been used to observe diffraction from the flux-line lattice in high temperature superconductors. This technique is particularly useful in such systems as it allows observations to be made over a wide range of temperature and magnetic field. Experiments on the systems K{sub 0.4}Ba{sub 0.6}BiO{sub 3} and YBa{sub 2}Cu{sub 3}O{sub 7--8} will be described with applied magnetic fields of up to 4 Tesla and for temperatures from 2K to {Tc}.

Date: January 1, 1991

Creator: Paul, D.McK. (Warwick Univ., Coventry (United Kingdom). Dept. of Physics); Forgan, E.M.; Cubitt, R.; Lee, S.L. (Birmingham Univ. (United Kingdom)); Mook, H.A. (Oak Ridge National Lab., TN (United States)) & Timmins, P. (Institut Laue-Langevin, 38 - Grenoble (France))

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Defect structures in YBa/sub 2/Cu/sub 3/O/sub 7-x/ produced by electron irradiation

Defect structures in YBa/sub 2/Cu/sub 3/O/sub 7-x/ produced by electron irradiation at 300/sup 0/ K were investigated by transmission electron microscopy. Threshold energies for the production of visible defects were determined to be 152 keV and 131 keV (+- 7 keV) in directions near the a and b (b > a) axes (both perpendicular to c, the long axis in the orthorhombic structure), respectively. During above threshold irradiations in an electron flux of 3 x 10/sup 18/ cm/sup -2/ s/sup -1/, extended… more

Date: December 1, 1987

Creator: Kirk, M.A.; Baker, M.C.; Liu, J.Z.; Lam, D.J. & Weber, H.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Gamma-spectrometry with Compton suppressed detectors arrays

Recent results of experiments performed with two different Compton-suppressed detectors arrays in Daresbury and Berkeley (/sup 163,164/Yb and /sup 154/Er, respectively), are presented together with a brief description of the national French array presently under construction in Strasbourg. 25 refs., 15 figs.

Date: January 1, 1985

Creator: Schueck, C.; Hannachi, F.; Chapman, R.; Lisle, J. C.; Mo, J. N.; Paul, E. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Anisotropy of oxygen tracer diffusion in YBa sub 2 Cu sub 3 O sub 7-. delta. single crystals

The crystal structure of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} strongly suggests that the diffusion of oxygen in this material will be highly anisotropic, with diffusion in the ab plane being much faster than diffusion parallel to the c axis, and this has been assumed in most analyses of diffusion in YBa{sub 2}Cu{sub 3}O{sub 7-{delta}}. The present data confirm this hypothesis; the diffusion coefficient in the ab plane is several orders of magnitude greater than the diffusion coefficient along th… more

Date: September 1, 1989

Creator: Rothman, S. J.; Routbort, J. L.; Liu, J.-Z.; Downey, J. W.; Thompson, L. J.; Fang, Y. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Electron beam induced oxygen in YBa sub 2 Cu sub 3 O sub 7-x superconductors

Thin foils of bulk YBa{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) superconductors were subjected to electron irradiation in a Transmission Electron Microscope (TEM). The resulting disordering of the oxygen atoms and vacancies in the Cu-O planes was monitored by measuring the splitting of the (110) diffraction spots in the (001) diffraction pattern. Samples were irradiated at 83K with 100, 150, 200 and 300kV electrons. The 100kV electrons did not cause any disordering, even after prolonged irradiation. Th… more

Date: January 1, 1989

Creator: Basu, S.N.; Roy, T.; Mitchell, T.E. & Nastasi, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Effects of ambient background gases on YBCO plume propagation under film growth conditions: Spectroscopic, ion probe, and fast photographic studies

The formation, composition, and propagation of KrF laser-produced plasmas from Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7-x} have been studied with emphasis on topics relevant to film growth by pulsed-laser deposition. Spatially and temporally resolved, high-resolution optical absorption and emission spectroscopy, fast ion probes, and fast photography (obtained with a gated, image-intensified CCD array detector (ICCD)) are employed to investigate both emitting and non-emitting species in the laser plume… more

Date: September 1, 1991

Creator: Geohegan, D.B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Non-stoichiometric defects in YBaCuO thin films

Defects in superconducting YBaCuO thin films deposited by laser ablation are investigated by high resolution transmission electron microscopy. Micrographs reveal numerous defects in the YBaCuO film, falling into four basic classes. One of these is an interesting, non-stoichiometric helical defect structure which possibly corresponds to a growth-related screw dislocation. In general, defects in the YBaCuO film are associated both with growth geometry and with local deviations in stoichiometry. S… more

Date: April 1, 1991

Creator: Fendorf, M.; Tidjani, M.; Burmester, C.; Gronsky, R. (Lawrence Berkeley Lab., CA (United States)) & Wille, L. (Florida Atlantic Univ., Boca Raton, FL (United States). Dept. of Physics)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Formation and characterization of fission-product aerosols under postulated HTGR accident conditions

The paper presents the results of an experimental investigation on the formation mechanism and physical characterization of simulated nuclear aerosols that could likely be released during an HTGR core heat-up accident. Experiments were carried out in a high-temperature flow system consisting essentially of an inductively heated release source, a vapor deposition tube, and a filter assembly for collecting particulate matter. Simulated fission products Sr and Ba as oxides are separately impregnat… more

Date: July 1, 1982

Creator: Tang, I.N. & Munkelwitz, H.R.

Item Type: Article

Partner: UNT Libraries Government Documents Department