高T_■^C超导材料制备中补氧量及氧缺位数对超导电性的影响

The Effect of Compensation Amounts of Oxygen and Oxygen-deficiency on the Superconductivity in the Synthetic Process of High T_c Y-Ba-Cu-O Superconductor

对BaCO_3、CuO、Y_2O_3和Y_(0.4)Ba_(0.6)CuO_(3-x)进行了TG-DTA分析。结果表明,参与固相反应的除CuO外还有Cu_2O,Y_(0.4)Ba_(0.6)CuO_(3-x)的烧结样品,在氧气氛中,于950～970℃出现相变,在416℃保温退火,TG增重1％,样品具有超导电性;在氩气氛中于845℃TG失重约1.14％,失去超导电性,再将其置于氧气氛中,TG最大增重约0.3％,超导电性未完全恢复,Y-Ba-Cu-O系列材料的超导电性与适量的氧缺位数密切相关。

A superconductor Y_(0.4)Ba_(0.6)CuO_(3-x) was prepared with BaCO_3, CuO, Y_2O_3 and studied by using the TG-DTA method. It was found that besides CuO, Cu_2O also participated in the solid-state reaction. A phase transition was observed at 950～970℃ in oxygen atmosphere for the sintered Y_(0.4)Ba_(0.6)CuO_(3-x), After sintered and then cooled slowly at 416℃ in oxygen,and when the additional amount of oxygen was of about 1%, the material had a good superconductivity. Measuring the TG in argon atmosphere for the superconducting sample treated in oxygen, a loss in weight at 845℃ was of about 1.14% and its superconductivity in liquid nitrogen disappeared. Then putting it into oxygen at 900℃, the maximum increment of oxygen was of about 0.3% and all superconductivities were not recovered. After adding the oxygen by after-treatment, the Y_(0.4)Ba_(0.6)CuO_(3-x) superconductor had an oxygen-deficiency of about 0.635. Experiments show that a good superconductivity of Y_(0.4)Ba(0.6)CuO_(3-x) is closely related to the 'appropriate' oxygen-deficiehcy (～0.635).