热处理温度对Bi-2212喷雾热分解超导粉末成相和性能的影响

Effect of Heat Treatment Temperature on Phase Formation and Properties of Bi-2212 Spray Pyrolysis Powder

摘要:

采用喷雾热分解法制备了Bi₂Sr₂CaCu₂O_x(Bi-2212)初级粉末,系统地研究了热处理温度对粉末成相和性能的影响。使用TG-DSC分析初级粉末的失重和相变情况,采用XRD分析粉末的相组成,通过SEM观察粉末的微观形貌,采用磁化法对样品的超导物理性能进行判定。结果发现,535~570℃,喷雾热分解初级粉末中的硝酸盐残留物逐渐分解；605~640℃,Bi-2201相形成；温度达到775℃,Bi-2212相开始形成,随热处理温度的提高,粉末结晶度持续增加,Bi-2212相含量先增加后减少,860℃是最佳的成相烧结温度。另外,通过对DSC曲线和M-T曲线的深入分析发现,先进行640℃的低温预分解,再进行860℃的高温成相烧结,可进一步改善最终粉末的质量。

Abstract:

Bi₂Sr₂CaCu₂O_x (Bi-2212) primary powder was prepared by spray pyrolysis method. The effect of heat treatment temperature on powder phase formation and properties was systematically studied. The weight loss and phase transformation of the primary powder were analyzed by TG-DSC, the phase composition of the powder was analyzed by XRD, the microstructure of the powder was observed by SEM, and the superconducting physical properties of the samples were determined by the magnetization method. It was found that at 535~570℃, the nitrate residues in the primary powder of Spray Pyrolysis gradually decomposed; at 605~640℃, the Bi-2201 phase was formed; when the temperature reached 775℃, the Bi-2212 phase began to form, With the increase of heat treatment temperature, the crystallinity of the powder continued to increase, and the content of Bi-2212 phase first increased and then decreased. 860℃ was the best phase-forming sintering temperature. In addition, through the in-depth analysis of the DSC curve and the M-T curve, it was found that the low temperature pre-decomposition at 640°C first, and then the high temperature phase-forming sintering at 860°C could further improve the quality of the final powder.