IMPROVEMENT OF FLUX PINNING IN THE AG-CLAD BI-PB-SR-CA-CU-O WIRES THROUGH THE USE OF A SHORT-PERIOD MELT PROCESSING

A significant enhancement of the J(c) in magnetic field in the Ag-clad Bi-Pb-Sr-Ca-Cu-O (BPSCCO) wires has been achieved by using a short period melt processing. The weak links have been largely eliminated in the melt-processed tapes which exhibits a 3-10-fold increase in the J(c) at 77 K and 1 T over the normally processed tapes. For tapes with a thickness 80-mu-m 60% of melt-processed samples have the J(c) values between 10 000 and 27 000 A/cm2 at 77 K in zero field. The irreversibility lines determined using ac susceptibility measurements under dc fields confirmed the improvement of flux pinning in the melt-processed tapes compared with the normally processed tapes. The improved J(c)-H characteristics may be attributed to the desirable microstructures produced from the high T(c) phase formation-decomposition-recovery process through the use of a short period melting.