Dominated Factors for J_c-B Characteristics of Bi-based High-T_c Superconducting Wires

Abstract

BiPbSrCaCuO silver sheathed high-T_c superconducting wires were fabricated through the solid reaction method. Maximum critical current density is 3.0×10⁴A/cm² at 77.3K in a zero magnetic field, 1.5×10⁴A/cm² at 0.1 Tesla and 3.3×10³A/cm² at 1 Tesla. We propose that the magnetic field dependence of J_c of the wire is dominated by the Lorentz force which works perpendicular to the c-axis, caused by the transport current with c-axis component crossing grain boundaries when the magnetic field was applied parallel to the plane of the wire. While, when the magnetic field was applied perpendicular to the plane, it was dominated by the pinning force in the grains.