Superconductor and precursor therefor, their preparation and use of superconductor

Abstract

A superconductor comprising a compound of the formula (II): R.sub.1+x Ba.sub.2-x Cu.sub.3 O.sub.7-y1 (II) wherein not less than 40% of a crystal of the superconductor shows phase separation, and at (temperature, magnetic field) of (77›K!, O›T!) and (77›K!, 4›T!), a critical current density is not less than 10,000 A/cm.sup.2, which is obtained by heating a precursor which is a solid solution of the formula (I): R.sub.1+x Ba.sub.2-x Cu.sub.3 O.sub.7-y (I) wherein not more than 10% of a crystal of the solid solution shows phase separation, so that phase separation is formed in the crystals at a phase separation temperature, and introducing oxygen; and a superconductor comprising a compound of the formula (II): R.sub.1+x Ba.sub.2-x Cu.sub.3 O.sub.7-y1 (II) wherein not more than 10% of a crystal of the superconductor shows phase separation, and in a magnetic field of not less than 1›T! at a constant temperature of 77›K!, a critical current density is less than 10,000 A/cm.sup.2, which is obtained by introducing oxygen into the precursor (I) at a temperature less than the lower limit of the phase separation temperature. According to the method of the present invention, a superconductor having a high Jc or having different properties with respect to Jc, which is unobtainable by the conventional production method, can be obtained using the conventional materials.

Dependencies are inferred from the claim text.