Bi_（1．5）Pb_（0．5）Sr_（1．5）Ln_（0．5）CuO_（6＋δ）（Ln＝La，Pr，Nd）超导体中晶体结构对超导电性的影响

Crystal structure effect on superconducting properties in Bi 1.5 Pb 0.5 Sr 1.5 Ln 0.5 CuO 6+δ (Ln=La,Pr,Nd)

利用Ｘ衍射分析等手段，研究了Ｂｉ２－ｘＰｂｘＳｒ２－ｗＬｎｗＣｕＯ６＋δ（Ｌｎ＝Ｌａ，Ｐｒ，Ｎｄ）超导体中ｘ＝ｗ＝０．５三种样品的晶体结构和超导电性．结果表明，除样品的氧含量和不同价正离子的置换会影响ＣｕＯ２面载流子浓度外，晶体结构的变化也会间接影响电荷转移，进而影响ＴＣ值；ＣｕＯ２面上Ｃｕ（Ｐ）和顶角氧Ｏ（Ａ）的键长。

The substitution of Sr by rare earth element La, Pr and Nd are investigated in the compound Bi 1.5 Pb 0.5 Sr 1.5 Ln 0.5 CuO 6+δ . Its influence on the superconducting properties as well as on the structure is studied by X ray diffraction, AC susceptibility, resistivity and oxygen content measurements. These results show that the change of crystal structure also influences the superconductivity indirectly, because of a change in bond length, affecting a charge transfer to or from CuO 2 planes. It is also proposed that d A(the Cu(P) O(A) bond length) may be a important parameter affecting superconductivity.