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以热重分析(TGA)、X 射线衍射及电阻-温度关系测定等方法,研究了水及水蒸气于285-1223K 间对 YBa_2Cu_3O_(7-x)超导材料的超导电性退化、水解及热重变化等过程的影响.YBa_2Cu_3O_(7-x)试样在水及水蒸气冷凝于试样表面的水膜的作用下,将逐渐水解为 BaCO_3、CuO 及 Y_2O_3等产物.当试样或水蒸气的温度高于373K 时,水蒸气对YBa_2Cu_3O_(7-x)的晶体结构与超导电性无明显影响.在20%H_2O+80%O_2的气体介质中,YBa_2Cu_3O_(7-x)于373-1223K 问的 TGA 曲线与在常压大气中相似,其放-吸氧及相变过程是完全可逆的.自1223K 降温至373K,YBa_2Cu_3O_(7-x)恢复原来结构与性能.
The degradation of superconductivity, hydrolysis and heat of YBa 2 Cu 3 O 7-x superconducting materials between 285 and 1223 K in water and water vapor were investigated by means of TGA, X-ray diffraction and resistance-temperature relationship analysis. YBa_2Cu_3O_ (7-x) sample gradually hydrolyzed into products such as BaCO_3, CuO and Y_2O_3 under the action of water film and water vapor condensed on the surface of the sample.When the sample or water vapor At temperatures higher than 373K, water vapor has no obvious effect on the crystal structure and superconductivity of YBa_2Cu_3O_ (7-x). In the gas medium of 20% H_2O + 80% O_2, YBa_2Cu_3O_ (7-x) The TGA curves are completely reversible, similar to those in the atmosphere at atmospheric pressure, and their oxygen absorption and phase transition are completely reversible. The structure and properties of YBa_2Cu_3O_ (7-x) restore to YBa_2Cu_3O_ (7-x) after cooling from 1223K to 373K.