摘要
采用 TG-DTA 热分析和 X 射线衍射相结合的方法,研究了由不同原料制取单一相 YBa2-Cu_3O_(7-(?))超导体的合成反应机理。试验结果表明,YBa2Cu_3O_(7-(?))的形成经历两个反应阶段,首先形成 BaCuO_2和 Y_2Cu_2O_5,随后这两个二元复合氧化物化合形成 YBa2Cu_3O_(7-(?))。各步反应温度受钡盐种类控制,采用 Ba(NO_3)_2原料,在750℃即可表现出超导性,T_c 达86K。
The reaction mechanism during the synthesis of superconductorYBa_2 Cu_3 O_(7-(?)) has been investigated by TG-DTA thermal analysis and X-raydiffraction method.The starting materials used are carbonats,nitrades andcoprecipitation of oxalates of Y,Ba and Cu respectively.The experimentalresults show that there are two steps of the reaction for the formation of su-perconductor YBa_2 Cu_3 O_(7-(?)).The binary complex oxides are firstly formed,theoxides above mentioned react each other to form the superconducting phase.The temperatures of the reaction stages depend on the species of Ba^(2+).UsingBa(NO_3)_2 as one of starting materials,the superconductivity appears at lowertemperature(about 750℃) as compared with BaCO_3 materials.
