铅掺杂Bi系超导体正电子寿命研究

Positron lifetime studies of Pb-Doped Bi-Based superconductors

在室温下测量了Ｂｉ２－ｘＰｂｘＳｒ２ＣａＣｕ２－ｘＭｇｘＯ８＋δ超导体的正电子寿命，发现正电子体寿命τｂ随着Ｐｂ含量ｘ的增加而减小；测量了转变温度Ｔｃ结果表明，Ｍｇ替换不影响电子结构，Ｐｂ替换使电子从Ｃｕ－Ｏ面迁移到Ｂｉ－Ｏ层，并导致ＣＵ－Ｏ面空穴浓度增加，转变温度Ｔｃ减小．

The positron lifetimes are measured for Bi2-x PhxSr2CaCu2-x MgxO8+δ superconductors. A decrease in positron bulk lifetime with increasing Pb content has been observed in 2212 phase. With the measurement of superconductiog transition temperature Tc, our study shows that the substitution of Pb for Bi causes some electrons transferred from Cu-O planes to Bi-O layers. This results in an increase in the hole concentration in the Cu-O planes and a decrease in the Tc of the system.