【摘要】 研究了Ｓｎ作Ｃｕ位元素替代的ＹＢａ２Ｃｕ３－ｘＳｎｘＯｙ超导体系（ｘ＝０－１．５）的正电子寿命谱，计算了局域电子密度和缺陷浓度的变化；发现了存在于高浓度替代区域（ｘ＝０．８－１．０）的正电子湮没特征；讨论了对超导电性的影响以及相应的物理机制。更多还原

【Abstract】 The positron lifetime spectra of the YBa2Cu3-xSnxOy system have been measured and the local electron density ne and vacancy concentration Cv have been calculated as a function of Sn substitution x. The results show that a sigificant Sn-substitution dependence exists. For lower x(<0.4), ne has a big continual variation and for higher x(>0.8), it is level off with a value of about 5.6×1023cm-3. But for Cv a big anomalous change occurs between x=0.8-1.0 and this may be the attributed to the structural phase transition.更多还原