ZN AND GA SUBSTITUTION IN SUPERCONDUCTING YBA2CU4O8

We have presented the results of Zn and Ga substitution in place of Cu in YBa2Cu4O8 (Y-124). The samples of YBa2(Cu1-xZnx)4O8 with x=0.00-0.20 and YBa2(Cu1-xGax)4O8 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 a0, b0 and c0. With Ga substitution in Y-124, a0 and b0 values tend to come closer and the c0 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 YBa2Cu3O7-delta system.