High-field critical current densities in Bi2Sr2Ca1Cu2O8+x/Ag wires

Abstract

Bi₂ Sr₂ Ca₁ Cu₂ O_8+x /Ag wires have been produced by using the ‘‘powder in tube’’ method and an appropriate annealing procedure. At 77 K these wires yield critical current densities up to 1.2×10³ A/cm² in zero magnetic field. Using ac susceptibility measurements it is shown that flux creep is limiting the critical current density at temperatures above ∼20 K. At lower temperatures flux creep becomes insignificant. At 4.2 K critical current densities up to 5.5×10⁴ A/cm² in zero magnetic field and up to 1.5×10⁴ A/cm² in a field of 26 T could be achieved, rendering possible the use of this material for very high field application.