Search

Implementation of improved processing for BaF/sub 2/ ex situ YBCO coatings from e-beam evaporated precursors enables faster conversion with rates up to 12 /spl Aring//s and critical currents I/sub c/ at 77 K greater than 350 A/cm-width on a RABiTS template. Details of the faster processing are described and compared to an earlier slower process. A linear relation between I/sub c/ and YBCO layer thickness provides evidence of new opportunities to further improve I/sub c/.

Magneto-optical imaging, electromagnetic measurements and SEM have been used for the characterization of a monocore BSCCO tape made by oxide powder-in-tube process which had a transport J/sub c/ (77 K, 0 T) of 37 kA/cm/sup 2/. Our study evaluates the connectivity between superconducting grains and reconstructs the local current distribution at

The phase and microstructural evolution, and critical current density of (Bi,Pb)-2223/Ag tapes prepared from a variety of precursor powders have been investigated. Correlations between the reaction kinetics, the microstructure and the critical current density are developed. A mechanism for the BSCCO-2223 phase formation depending on the precursor phase assemblage is presented. Magneto-optical imaging shows that high J/sub c/ samples (J/sub c/ (77 K, 0 T) /spl sim/35 kA/cm/sup 2/) are well connected longitudinally but strongly sub-divided by longitudinal cracks. The performance of BSCCO-2223 tapes should be further improved by controlling the liquid phase to better heal the cracks.