Abstract: A new superconducting material composed mainly of compound oxide represented by the general formula:Tl.sub.h Ca.sub.j .alpha..sub.k(1-y) .beta..sub.ky Cu.sub.m O.sub.nwherein".alpha." represents Ba or Sr;".beta." represents any one of elements selected from a group comprising Na, K, Rb and Cs;"h", "j", "k", "m" and "n" are the atomic ratios each satisfies the following range:1.ltoreq.h.ltoreq.3, 1.ltoreq.j.ltoreq.3, 1.ltoreq.k.ltoreq.3,2.ltoreq.m.ltoreq.4 and 5.ltoreq.n.ltoreq.15 and"y" is a number which satisfies a range of 0.05.ltoreq.y.ltoreq.0.8.

Abstract: Provided herein is a method of efficiently preparing a thin film having a higher critical temperature as to an oxide superconducting material containing Tl. A thin film of an oxide containing Tl is formed and then heat treated at a temperature of about 850.degree. to 950.degree. C. for a short time, and thereafter further heat treated at a temperature, which is lower than the preceding heat treatment temperature, of at least about 750.degree. C. for a long time. The thin film is heat treated in an atmosphere having an oxygen partial pressure of not more than about 0.1 atm. In formation of a Tl superconducting thin film, on the other hand, a 1212 phase layer is reacted with an amorphous Ca--Cu--O layer to form a 1223 phase layer, or a layer containing volatile metal elements (Tl, Bi and Pb, for example) and oxygen is reacted with another layer containing other elements than the volatile metal elements to form a superconducting film having a high critical temperature.

Abstract: A method of manufacturing an oxide superconductor by heating a raw material for an oxide superconductor composed of MBa.sub.2 Cu.sub.3 O.sub.7-.delta., where M represents at least a single element selected from a group of Y, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu, to a temperature higher than a peritectic reaction temperature for melting the same and thereafter reducing the temperature to the peritectic reaction temperature to crystallize the oxide superconductor by peritectic reaction. A method of forming a dispersion solution of powder of a raw material for an oxide superconductor and applying the same on a substrate to prepare a thick film. A method of dipping a single crystal of M.sub.2 BaCuO.sub.5 in a molten solution of a mixture of BaCuO.sub.2 and CuO to form a thin film of an oxide superconductor on the single crystal. A method of manufacturing a bulky oxide superconductor by dipping a porous sintered material of M.sub.2 BaCuO.sub.5 in a molten solution of a mixture of BaCuO.sub.2 and CuO.