Cd对CaLaBaCu_3O_y体系超导电性的淬灭作用

SUPPRESSION OF SUPERCONDUCTIVITY IN CaLaBaCu_3O_y SYSTEM BY Cd DOPING

研究了Cd替代Ca对CaLaBaCu_5O_7体系超导电性的影响.电阻率测量结果表明,T_c随Cd含量x的增加单调下降,同时正常态电阻率随x增加而上升.在x=0-1范围内,体系经历超导-类半导体-绝缘体转变.Hall测量结果表明,CuO_2 面内迁移空穴浓度p_(ab)随Cd含量增加而单调下降,这与Tc的变化相对应.样品的热重测量结果表明,氧含量对Ca_(1-2)Cd_5LaBaCu_5O_7,体系的正常态和超导态性质产生很大影响.Cd替代Ca导致Cu-O链上的氧空缺.随着Cd含量的增加,氧含量单调下降.Cd淬灭T_c的原因,可归结于Cd的替代导致了体系中氧含量的减少.

Superconducting behavior of the superconductor CaLaBaCu3Oy has been studied by substitution of Cd for Ca. Electrical resistivity measurements show superconducting critical temperature (Tc) decreases monotonously with increasing concentration of the substituent Cd ions, meanwhile normal state resistivity increases. Meatal-se-miconductor like-insulator transitions are displayed on the resistivity versus temperature curves in the substitution ranger x=0-1. The Hall effect measurements show that the concentration of mobile holes in CuO2 plane Pah decreases with increasing Cd content x. There exits correlation between Tc and Pab. Thermogravime-try studies of samples show that the oxygen content influences greatly on the normal and superconducting properties of Ca1-x CdxLaBaCu3Oy system. The substitution of Cd for Ca leads to the deficiencies of oxygen in Cu-O chain. As substituent Cd concentration x increases, the oxygen content decreases monotonously. It is concluded that the reason why Cd leads to the suppression of Tc is the reduction of oxygen content caused by substitution of Cd for Ca.