Process of preparing superconductive oxide complexes containing l, ba,

Abstract

A superconductor material having a current density, J, of from about 30,000 to about 85,000 amps/cm.sup.2 at zero magnetic field and 77.degree. K is disclosed. The 123 superconductor, of the formula L.sub.1 Ba.sub.2 Cu.sub.3 O.sub.6 +.delta. wherein L is preferably yttrium, is capable of entrapping sufficiently high magnetic fields and exhibits a low microwave surface resistance. The process of preparing the superconductor comprises compacting the bulk product, L.sub.1 Ba.sub.2 Cu.sub.3 O, and then sintering the reaction product at a temperature between about 40.degree. C. to about 90.degree. C. below its melting point, i.e., for Y.sub.1 Ba.sub.2 Cu.sub.3 O.sub.6 +.delta. at a temperature of approximately 940.degree. C. The composition is then heated in a preheated chamber maintained at approximately 1090.degree. C. to about 1,200.degree. C. (approximately 1,100.degree. C. for Y.sub.1 Ba.sub.2 Cu.sub.3 O.sub.6 +.delta.) until it has been decomposed, and is then rapidly cooled to a temperature between about 10.degree. C. to about 30.degree. C. above its melting point, i.e. for Y.sub.1 Ba.sub.2 Cu.sub.3 O.sub. 6 +.delta. a temperature of 1030.degree. C., and then is controlled cooled at a rate of 1.degree. C./hr until it reaches a temperature of about 20.degree. C. to about 40.degree. C. below its melting point, i.e., for Y.sub.1 Ba.sub.2 Cu.sub.3 O.sub.6 +.delta. a temperature of 980.degree. C. The composition is steadily held at this temperature for at least eight hours, and then cooled to a temperature of approximately 400.degree. C. below its melting point (for Y.sub.1 Ba.sub.2 Cu.sub.3 O.sub.6 +.delta. approximately a temperature of 600.degree. C.). The material is then slowly cooled by another 200.degree. C. and is then annealed in oxygen.