Method for production of superconducting oxide tape and superconducting

Abstract

A method for the production of a superconducting oxide tape having a Bi.sub.2 Sr.sub.2 Ca.sub.2 Cu.sub.3 O.sub.10 (Bi-2223) structure interposed between silver sheets, which method consists essentially of preparing a sandwich structure having interposed between silver sheets a molded layer of a superconducting oxide precursor powder consisting essentially of Bi, Pb, Sr, Ca, Cu, and O obtained from a raw material substance composed of, in atomic composition ratio, 1.00 of Bi, 0-0.2 of Pb, 0.9-1.1 of Sr, 0.9-1.1 of Ca and 1.3-1.7 of Cu, and O, heating the sandwich structure in an atmosphere consisting of oxygen and an inert gas, having an oxygen partial pressure in the range of 0-5%, and kept at a temperature in the range of 830-850.degree. C., thereby melting the molded layer, then causing the atmosphere to retain the heating temperature and meanwhile increasing the oxygen partial pressure, thereby inducing precipitation of crystal grains possessing a Bi.sub.2 Sr.sub.2 CaCu.sub.2 O.sub.8 (Bi-2212) structure and excelling in orientation, and subsequently maintaining the oxygen partial pressure and temperature at the time of precipitation of the crystal grains, thereby transforming the structure into the (Bi-2223) structure while retaining the particle diameter of the crystal grains and the state of orientation, and superconducting oxide tape produced by the method.