Effect of Pb and Sb substitutions on superconducting Bi-Sr-Ca-Cu-O prepared by oxidation of liquid-quenched precursor alloys

Abstract

We have produced a series of precursor alloys (Bi1−xPbx)2 Sr2Ca2Cu3 (0≤x≤0.5) by planar flow casting. After oxidation and annealing in air, essentially 2212 and 2223 phases are present. The proportion of the 2223 phase increases as x increases from 0 to 0.3, at which composition mainly the 2223 phase is obtained with Tc (ρ=0) =105 K, and Jc(100 K) ≊200 mA/cm2 . More Pb addition reduces the amount of the 2223 phase and yields Ca2 PbO4. With Sb addition, a higher T(onset) ) near 125 K is obtained for (Bi0.85Pb0.10Sb0.05)2 Sr2Ca2Cu3Oy, corresponding to a multiphase material. A semiconducting behavior is observed when Sb≥10%.