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氧化物超导材料YBa_2Cu_3O_(7-δ)的T_c值与其氧含量密切相关,当氧含量接近于7 时,T_c值可达92K,当δ大于0.6时,则失去超导性,其结构也从正交相转变为四方相。YBCO中的主要载流子是氧空穴,它与结构中的氧缺位状况密切关联。郑州大学物理系高之爽等发现YBCO(T_c=91.6K)超导材料在真空(10~(-1)Pa)中放置5天后,其T_c降为83K,热重结果表明样品存在脱氧现象。为此,我们在重水反应堆旁的中子粉末衍射仪上进行了脱氧前后样品的中子衍射实验。结果见表1。
The Tc value of YBa2Cu3O7 (7-δ) is closely related to its oxygen content. When the oxygen content is close to 7, the Tc value can reach 92K. When δ is larger than 0.6, the superconducting property is lost. The structure of Orthogonal phase into a square phase. The main carrier in YBCO is oxygen vacancies, which are closely related to the oxygen vacancy status in the structure. The results showed that the Tc of the YBCO (T_c = 91.6K) superconducting material was reduced to 83K after being placed in vacuum (10 ~ (-1) Pa) for 5 days and the thermogravimetric results showed that there was deoxidation in the sample. For this reason, we carried out neutron diffraction experiments on samples before and after deoxidation on neutron powder diffractometer beside heavy water reactor. The results are shown in Table 1.