[en] This patent describes a composition for the lossless transmission of electrical current, it comprises: a superconducting thin film epitaxially deposited on a oriented surface of a single crystal KTa_1-zNb₂O₃ substrate, where z is 0 to 1, wherein the superconducting thin film is selected from the group consisting of YBa_2-Cu₃O₇, Y₂Ba₄Cu₈O₂₀, a compound wherein a trivalent rare earth element replaces yttrium in compound YBa₂Cu₃O₇, and a compound wherein scandium replaces yttrium in the compound YBa₂Cu₃O₇

[en] This JueL-report is a documentation of solubility data of the hydrogen isotopes protium and/or deuterium and/or tritium in the metals V, Nb, Ta, Pd and alloys V_1-xNb_x, V_1-xTa_x, Nb_1-xMo_x, Pd_1-xAg_x. The solubility has been determined by measurements of the pressure drop or increase, the pressure itself, the sample temperature and by the knowledge of the effective temperature, the volume and the sample mass. The JUeL-report shows the hydrogen solubility graphically in the form of the usual isotherms, but the main purpose is the numerical presentation of the equilibrium pressures, sample temperatures and hydrogen concentrations (given as ratio of hydrogen - to metal atoms). (orig.)

[en] A method is disclosed for fabricating YBa₂Cu₃O₇ superconductor layers with the capability of carrying large superconducting currents on a metallic tape (substrate) supplied with a biaxially textured oxide buffer layer. The method represents a simplification of previously established techniques and provides processing requirements compatible with scale-up to long wire (tape) lengths and high processing speeds. This simplification has been realized by employing the BaF₂ method to grow a YBa₂Cu₃O₇ film on a metallic substrate having a biaxially textured oxide buffer layer

[en] A system allowing CAMAC data acquisition at better than a millisecond per event while controlling the experiment with a FORTRAN real time program is presented. The structure of the technique allows an experimenter with only FORTRAN experience to prepare his own data acquisition program. (Auth.)

[en] Phase diagrams of the Ba₂RCu₃O_6+x(R = Nd, Sm, Gd, Y, and Er) superconductors, prepared under 100 Pa O₂ at 810 deg. C, reflect the trend of the lanthanide contraction. The single-phase regions of Ba_2-x(Nd_1+x-yR^'_y)Cu₃O_6+z for R^' = Gd, Y and Yb, and of Ba_2-x(R_1+x-yY_y)Cu₃O_6+z for R = Eu and Gd were determined. Using these data, both flux-pinning and melting properties can be tailored and optimized. The presence of a low temperature melt during formation of the Ba₂YCu₃O_6+x phase from barium fluoride amorphous precursor films is deemed important for producing quality tapes, and hence for rapid advancement of second-generation RABiTS/IBAD coated conductor technology. Our search for low melting liquid has focused on compositional vectors within the Ba, Y, Cu-O, F reciprocal system

[en] Precision density measurements on dilute hydrides, deuterides and tritides of V, Nb and Ta are presented. From the essentially linear decrease of the density with solute content, values are obtained for the lattice expansion (Δ υ/Ω)sub(i) for each hydrogen isotope. The data strongly suggest a small decrease of (Δ υ/Ω) when going from H and D. The tritium values are close to those for H and D, but are less precise. The accuracy of the present density derived data set represents a considerable improvement over previous lattice parameter derived values for the lattice expansion. (author)

[en] Using a combination of Z-contrast imaging, scanning tunneling microscopy, and plan view diffraction contrast imaging, we have studied the growth and relaxation mechanisms of YBa₂Cu₃O_7-x deposited on MgO and SrTiO₃ substrates. Two-dimensional island growth occurs on SrTiO₃ substrates, with relaxation through the nucleation of dislocation half-loops. Then the threading dislocation segments with a screw component can lead to kinetic roughening through the development of growth pyramids. In contrast, growth on MgO occurs by true one-dimensional island growth (with no wetting layer), most of the interface being incommensurate with the substrate (although crystallographically aligned). Dislocations with both edge and screw components are generated on island coalescence. A highly anisotropic surface energy is shown to responsible for cell-by-cell c perpendicular growth being thermodynamically preferred, although at high supersaturations a transition a perpendicular growth occurs

[en] Atomic-resolution Z-contrast electron microscopy provides a directly interpretable image showing the location of high-Z atomic columns without the need for any structural models. Usually, the type of column may be identified from its intensity, and the structure and morphology of interfaces, ultrathin films, and superlattices are directly revealed. This has generated many insights into growth and relaxation phenomena. Since the Z-contrast image uses only electrons scattered through large angles, electron energy loss spectroscopy may be performed simultaneously using the transmitted beam, providing information on the local hole concentration from the fine structure of the oxygen-K absorption edge. The resolution achieved is below the coherence length, allowing a microscopic interpretation of transport properties. 7 figs, 14 refs

[en] Data as a function of magnetic field on two types of bicrystal grain boundaries (GB's) of high-T_c superconductors show a peak in the critical current and an unusual inverse hysteresis. These results support a mechanism for an enhanced GB critical current, arising from interactions of GB vortices with pinned Abrikosov vortices in the banks of a GB, as suggested by Gurevich and Cooley. A substantial fraction of this enhancement (of order a factor of 2 after field cooling) also occurs upon exceeding the critical current of the grains after zero field cooling. A bulk GB and an isolated GB from a coated conductor show qualitatively identical results

[en] Published in summary form only