PREPARATION OF TAPE OF SILVER COVERED BI-PB-CA-SR-CU-O ORIENTED POLYCRYSTAL SUPERCONDUCTOR

摘要

A silver tube with one open end is packed with a particulate mixture of reactants comprised of Bi.sub.2 CaSr.sub.2 Cu.sub.2 O.sub.8.+-. x, Ca. sub.2 CuO.sub.3, cupric oxide and lead oxide, the open end of the packed tube is plugged with silver, the resulting closed tube is swaged to increase the density of the packed mixture, the swaged tube is wire- drawn, uniaxial pressure is applied to the wire orienting the Bi.sub.2 CaSr.sub. 2 Cu.sub.2 O.sub.8.+-.x crystals with their c-axis parallel to each other forming an initial tape, the initial tape is fired to convert part of the Bi.sub.2 CaSr.sub.2 Cu.sub.2 O.sub.8.+-.x crystals to Bi.sub. 2-y Pb.sub.y Ca.sub.2 Sr.sub.2 Cu.sub.3 O.sub.10.+-.z crystals producing an intermediate tape containing dilated product, uniaxial pressure is applied to the resulting intermediate tape to remove the dilation in the product, and the pressed intermediate tape is fired to produce a tape comprised of silver enveloping a sintered body of Bi.sub.2-y Pb.sub.y Ca. sub.2 Sr.sub.2 Cu.sub.3 O.sub.10.+-.z.