Enhanced flux pinning in Ag-sheathed (Bi, Pb)₂Sr₂Ca₂Cu₃O_{10+ delta}tapes by post-annealing

Abstract

A significant enhancement of Jc in a magnetic field for Ag-sheathed Bi-Pb-Sr-Ca-Cu-O (BPSCCO) tapes has been achieved by post-annealing at reduced temperature after processing. This post-annealing at reduced temperature introduced extra oxygen into the oxide superconductor. Weak links were eliminated and Jc has been increased in the post-annealed tapes by a factor of 1.5 to 3 at 0 T over the normally processed tapes without post-annealing. The optimized Jc values for the post-annealed tapes ranged from 30000 to 57000 A cm-2 at 77.3 K and 0 T. The irreversibility lines measured by a DC SQUID exhibited an improvement in flux pinning in the post-annealed tapes compared with that in normally processed tapes. The introduced oxygen ions are responsible for the enhanced Jc and may affect two dimensionality in superconductivity for the BPSCCO system.