| 摘要 |
2048622 9009344 PCTABS00001 A superconductor material having a current density (J) of from about 30.000 to about 85.000 amps/cm2 at zero magnetic field and 77·K is disclosed. The 123 superconductor, of the formula L1Ba2Cu3O6+.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, L1Ba2Cu3O, and then sintering the reaction product at a temperature between about 40·C to about 90·C below its melting point, i.e., for Y1Ba2Cu3O6+.delta. at a temperature of approximately 940·C. The composition is then heated in a preheated chamber maintained at approximately 1,090·C to about 1,200·C (approximately 1,100·C for Y1Ba2Cu3O6+.delta.) until it has been decomposed, and is then rapidly cooled to a temperature between about 10·C to about 30·C above its melting point, i.e. for Y1Ba2Cu3O6+.delta. a temperature of 1,030·C, and then is controlled cooled at a rate of 1·C/hr until it reaches a temperature of about 20·C to about 40·C bellow its melting point, i.e., for Y1Ba2Cu3O6+.delta. a temperature of 980·C. The composition is steadily held at this temperature for at least eight hours, and then cooled to a temperature of approximately 400·C below its melting point (for Y1Ba2Cu3O6+.delta. approximately a temperature of 600·C). The material is then slowly cooled by another 200·C and is then annealed in oxygen.
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