Microstructure and Flux Creep Behavior of Ag-Sheathed Bi-Pb-Sr-Ca-Cu-O Tapes

TEM observations and flux creep measurements have been carried out for the Bi-Pb-Sr-Ca-Cu-O (BPSCCO) tapes, with and without the intermediate press process. A lot of dislocations were found in the grains of the pressed tape, which had 20,000 A/cm2 transport critical current density at 77 K, 0 T. Field and temperature dependence of the pinning potential U0 was summarized in ternary diagrams. It could be clearly recognized that the U0 for the BPSCCO tape was enhanced by the press. As a result, the intra-grain critical current density proved to be increased, and dislocations seemed to play a role in a pinning center.