Process for preparing superconductor of compound oxide of Bi-Sr-Ca-Cu system

Abstract

A compound oxide superconductor represented by the general formula: Bi.sub.4+d (Sr.sub.1-x, Ca.sub.x).sub.m Cu.sub.n O.sub.p+y in which, "d" is an amount of excess bismuth and satisfies a range of 0<d.ltoreq.1.2, "m" is a number which satisfies a range of 6.ltoreq.m.ltoreq.10, "n" is a number which satisfies a range of 4.ltoreq.n.ltoreq.8, "p"=6+m+n, "x" is a number which satisfies a range of 0<x<1, and "y" is a number which satisfies a range of -2.ltoreq.<y.ltoreq.+2. A preferred example is a compound oxide system having the following general formula: Bi.sub.4+d Sr.sub.4 Ca.sub.4 Cu.sub.6 O.sub.20+y in which "d" is a number which satisfies the range 0.4.ltoreq.d.ltoreq.1.2 and "y" is a number which satisfies a range of -2.ltoreq.y.ltoreq.+2. The critical current density (J.sub.c) is improved by increasing the amount of bismuth with respect to the stoichiometric amount. A superconducting thin film is deposited on a substrate by physical vapor deposition such as sputtering.

Dependencies are inferred from the claim text.