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in subjects: "Yttrium Compounds 360206* -- Ceramics, Cermets, & Refractories-- Radiation Effects"

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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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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

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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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Structure and flux pinning properties of irradiation defects in YBa sub 2 Cu sub 3 O sub 7-x

We review our investigations of defects produced in YBa{sub 2}Cu{sub 3}O{sub 7-x} by various forms of irradiation. The defect microstructure has been studied by transmission electron microscopy (TEM). Irradiation enhancements of flux pinning have been studied by SQUID magnetometry on single crystals. In many cases the same single crystals were used in both TEM and SQUID investigations. The primary atom recoil spectra for all the irradiations studied have been carefully calculated and used to co… more

Date: June 1, 1992

Creator: Kirk, M.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Application of MeV ions to the analysis and modification of high temperature superconducting materials

In analyzing the composition of high {Tc} superconducting materials using heavy-ion RBS we discovered that the electronic excitation of the target caused mixing to occur. To study this effect we made superlattice structures of alternating thin layers of Ba{sub 2}YCu{sub 3}O{sub 6+x} and BaF{sub 2}. At this point in the process some mixing has occurred, but the individual layers are still visible. However, as the bombardment continued the layers were mixed together. It may well be that one can u… more

Date: November 2, 1990

Creator: Tombrello, T.A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Radiation damage in YBa/sub 2/Cu/sub 3/O/sub 7/ by fast neutrons

The superconducting transition temperature of sintered YBa/sub 2/Cu/sub 3/O/sub 7/ decreases at a rate of 2.7 K/10/sup 18/ n/cm/sup 2/ (E > 0.1 MeV) for fast neutron irradiation. The critical current density J/sub c/ increases a factor of three at zero field and more than three at nonzero fields for fluences up to 2 x 10/sup 18/ n/cm/sup 2/. At both 7 and 75 K, J/sub c/ is decreasing with fluence near 3 x 10/sup 18/ n/cm/sup 2/.

Date: January 1, 1987

Creator: Willis, J. O.; Cost, J. R.; Brown, R. D.; Thompson, J. D. & Peterson, D. E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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TEM study of flux pinning defects in YBa sub 2 Cu sub 3 O sub 7-. delta. produced by 580 MeV Sn ion irradiation

Recent studies of high {Tc} superconductors irradiated with high energy heavy ions have indicated that a defect structure is produced which is extremely effective in pinning magnetic flux lines. In attempting to develop models to account for these observations, it is imperative to have a complete characterization of the defects responsible for the property enhancements. Hence, the defect microstructure produced in single crystal YBCO by 580 MeV Sn{sup 30+} irradiation, recently demonstrated to … more

Date: January 1, 1991

Creator: Wheeler, R.; Kirk, M.A.; Brown, R. (Argonne National Lab., IL (United States)); Marwick, A.D.; Civale, L. & Holtzberg, F.H. (International Business Machines Corp., Yorktown Heights, NY (United States). Thomas J. Watson Research Center)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Critical currents in proton irradiated YBa sub 2 Cu sub 3 O sub 7-. delta. crystals

A large enhancement in the critical current of YBaCuO crystals in magnetic field is observed after irradiation with 3 MeV protons. Critical current densities with values up to 2 {times} 10{sup 5} A/cm{sup 2} at 77 K and 1 T are observed. TEM studies show the presence of isolated clusters of defects after irradiation; however, an analysis of the critical current scaling indicates that these clusters are not the dominant pinning sites. The dose dependence of the current density suggests that the … more

Date: April 1, 1991

Creator: Civale, L.; McElfresh, M. W.; Marwick, A. D.; Worthington, T. K.; Malozemoff, A. P.; Holtzberg, F. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Fast neutron irradiation effects on magnetization relaxation in YBCO single crystals

A high-quality YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} single crystal has been investigated by torque magnetometry prior to and following fast neutron irradiation to a fluence of 2{times}10{sup 21} m{sup {minus}2} (E > 0.1 MeV). In addition to large enhancements of the critical current densities, which have been observed in similar form previously by Sauerzopf et al, we find a dramatic change in the relaxation behavior following irradiation. At low temperatures ({le} 50 k) the relaxation rates are … more

Date: July 1, 1991

Creator: Lensink, J.G.; Griessen, R. (Vrije Univ., Amsterdam (Netherlands). Faculty of Physics and Astronomy); Wiesinger, H.P.; Sauerzopf, F.M.; Weber, H.W. (Atominstitut der Oesterreichischen Universitaeten, Vienna (Austria)) & Crabtree, G.W. (Argonne National Lab., IL (United States))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Radiation induced amorphization in YBa2Cu3O7 and GdBa2Cu3O7 superconductors

The response of YBa2Cu3O7 and GdBa2Cu3O7 high temperature superconductors to particle irradiation is examined. Both ion and electron irradiations have been shown to first produce an orthorhombic-to-tetragonal transformation at doses roughly a factor of 10 higher. Analysis of the displacement stoichiometry that results from 120, 300, and 1000 keV electron irradiations, 400 and 500 keV O irradiations, and 300 keV helium irradiations indicate that the orthorhombic-to-tetragonal transformation is d… more

Date: January 1, 1988

Creator: Parkin, Don M. & Nastasi, Michael

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Irradiation defect structures in YBa sub 2 Cu sub 3 O sub 7 minus x and their correlation with superconducting properties

We review our work on irradiation effects in single crystal YBa{sub 2}CU{sub 3}O{sub 7-x}. Transmission electron microscopy has been employed to study the defect microstructures produced by irradiations with fast neutrons, MeV ions (Kr, Ne and p), and electrons. The atomic structure within defect cascades was investigated using 50 keV Kr and Xe ion irradiations to low doses. Evidence is shown for an amorphous structure with some incoherent recrystallization within individual cascades. Correlati… more

Date: November 1, 1990

Creator: Kirk, M.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Nature of radiation damage in ceramics

Efforts to determine the equivalence between different sources of radiation damage in ceramics are reviewed. The ways in which ceramics differ from metals are examined and proposed mechanisms for creation and stabilization of defects in insulators are outlined. Work on radiation damage in crystalline oxides is summarized and suggestions for further research are offered. (JRD)

Date: January 1, 1976

Creator: Bunch, J. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Structural effect in neutron irradiation of insulating ceramics

A vacuum gap irradiation capsule was designed and built to maintain a temperature of 740/sup 0/C during 6 weeks irradiation at EBR-II. Sixty-eight samples of 15 ceramic or metal-ceramic combinations were irradiated to a fluence of approximately 3 x 10/sup 21/ neutrons/cm/sup 2/, E greater than 0.1 MeV. Measurements of sample dimensions before and after irradiation were used to determine volume swelling. This parameter and the physical appearance of the samples are discussed. A primary applicati… more

Date: January 1, 1976

Creator: Hurley, George F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Flux pinning defects induced by electron irradiation in Y sub 1 Ba sub 2 Cu sub 3 O sub 7-. delta. single crystals

Single crystals of R{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7-{delta}}, (R=Y, Eu and Gd), have been irradiated with 0.4--1.0 MeV electrons in directions near the c-axis. An incident threshold electron energy for producing flux pinning defects has been found. In-situ TEM studies found no visible defects induced by electron irradiation. This means that point defects or small clusters ({le} 20 {Angstrom}) are responsible for the extra pinning. A consistent interpretation of the data suggests that the most … more

Date: June 1, 1992

Creator: Giapintzakis, J.; Lee, W. C.; Rice, J. P.; Ginsberg, D. M.; Robertson, I. M.; Kirk, M. A. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department