Preparation and properties of Pb-doped Bi-Sr-Ca-Cu-O superconductors

Electrical and magnetic properties of the superconducting oxides with nominal composition (Bi0.7 Pb0.3 )2Sr2Ca2 Cu3 Ox prepared from polymeric precursors have been investigated. Superconducting transition with zero-resistance temperature at T=108 K was achieved for a sample sintered at 840 °C under a low oxygen pressure. The critical current density at 77 K in a zero magnetic field is ∼400 A/cm2 , which is much higher than that of the Pb-free sample. Variations of the superconducting transition temperature, the critical current density, and magnetic properties with heat treatment time are discussed in connection with the structural properties.