Zn and Ga substitution in superconducting YBa 2Cu 4O 8

Abstract

We have presented the results of Zn and Ga substitution in place of Cu in YBa 2Cu 4O 8 (Y-124). The samples of YBa 2(Cu 1− x Zn x ) 4O 8 with x=0.00-0.20 and YBa 2(Cu 1− x Ga x ) 4O 8 with x=0.01-0.10 were synthesised at ambient oxygen pressure using sodium oxalate. With increase in concentration of Zn in Y-124 no significant change is observed in the values of the lattice parameters a 0, b 0 and c 0. With Ga substitution in Y-124, a 0 and b 0 values tend to come closer and the c 0 parameter decreases, resulting in decreased orthorhombicity of the unit cell. It is observed that Zn substitution in Y-124 depresses the T c( R=0) at a faster rate compared to Ga substitution in this system. The results are compared with the reported data for the YBa 2Cu 3O 7−δ system.