Effect of annealing and quenching on superconductivity in Pb and Sb-doped Bi2Sr2Ca2Cu3Ox

Samples of the series Bisub(1.9-x)PbxSbsub(0.1)Sr2Ca2Cu3Oy with x=0, 0.1, 0.2, 0.3 and 0.4 were prepared by the solid-state route. The X-ray and d.c. electrical resistivity data on furnace-cooled and quenched samples are presented. Though the starting composition is 2223, the end products were multiphase with 4334 as the major phase. A superconducting transition with Tc=100 K was observed in the pure 2223 sample after quenching. The furnace-cooled samples were metallic, while samples with x=0.1, 0.2 and 0.3 were superconducting after quenching. The amount of the 4334 phase decreases with increasing Pb content. Quenching seems to be favourable for the formation of the 4334 phase. (author). 13 refs., 6 figs., 2 tabs