Properties of polycrystalline Hg 1− xBi xBa 2Ca 2Cu 3O y superconductors

Abstract

Polycrystalline Hg 1− x Bi x Ba 2Ca 2Cu 3O y materials, with Bi-content x=0.1, 0.2 and 0.3, were prepared by a direct, one-step synthesis. Characterization methods included X-ray diffraction, SEM, and studies of the magnetization M. The T c's were 133.5, 133 and 128 K, respectively. The persistent current density J p falls off roughly exponentially with field H and temperature T. The irreversibility fields H irr( T)∼(1− T/ T c) n , with n≈3, were similar for the three materials. Analysis of the equilibrium M with London theory provided the London penetration depth λ( T).