论文部分内容阅读
用固态配料和硝酸盐共沉淀配料制备了各组份为(Bi_(1.85)Pb_(0.40))Sr_(1.95)Ca_(2.05)Cu_(8.10)的超导材料,研究了两种不同制备工艺对Bi系超导相形成过程、超导电磁性能和显微结构的影响.实验发现,由共沉淀制备的样品T_(c(zero))稳定性好,T_(c(zero))均在107.5K以上.SEM观察表明:共沉淀法制备的样品中超导相颗粒比固态配料制备的要细小、均匀,颗粒间连结紧密,与T_(c(zero))结果相符.但XRD相分析结果显示:固态配料样品中高温相含量高于共沉淀配料,共沉淀配料制备作品中高、低温相同时存在,但其交流磁化率—温度曲线上仅在120K附近出现相应于高温相的抗磁信号.研究认为,这是由于共沉淀配料烧成时,高温相容易在部分液相参与下,在低温相表面通过反应成核生长,导致在形成的高温相内部包裹有残余低温相的“内芯”.依此包裹模型可自洽地解释X射线相分析与电、磁性能测定结果间的矛盾,讨论了Bi系高温相的形成机理,为选择合理的制备工艺提供了依据.
The superconducting materials with (Bi_ (1.85) Pb_ (0.40)) Sr_ (1.95) Ca_ (2.05) Cu_ (8.10) were prepared by solid ingredients and nitrate coprecipitation. The effects of two different preparation processes Bi superconducting phase, superconducting magnetic properties and microstructures were investigated.The experimental results show that the T_ (c (zero)) prepared by coprecipitation has good stability and T_ (c) at 107.5K .The results of SEM showed that the superconducting particles in the sample prepared by the coprecipitation method were smaller and more uniform than those in the solid state, and the particles were closely connected with each other, which was consistent with the result of Tc (zero) However, the AC susceptibility-temperature curve shows the diamagnetic signal corresponding to the high temperature phase only in the vicinity of 120 K. The results show that the high temperature phase content in solid sample is higher than that of coprecipitation and coprecipitation preparation, , Which is due to co-precipitation ingredients firing, the high temperature phase is easy to participate in part of the liquid phase, the nucleation and growth by reaction at the low-temperature phase, resulting in the formation of the high-temperature phase wrapped within the residual low temperature phase “core.” This package model can explain X-ray phase analysis and electrical and magnetic measurements consistently Contradiction between the results, discussed the mechanism of formation of the Bi-based high-temperature phase, provide a reasonable basis for the selection of the manufacturing process.