Behavior of critical current density and grain misalignment of hot-pressed Bi-2223 bar current leads

Bi-2223 bar current leads were fabricated by a combination of cold isostatic pressing (CIP) and hot pressing (HP). The critical currents were measured at 77 K by varying external de magnetic field (B), which was applied parallel and perpendicular to the bulk sample surface, i.e., I-c (B//bar surface) and I-c (B perpendicular to bar surface), respectively. The critical current I-c and critical current density J(c) were 119 A and 300 A/cm(2), respectively, for the bar current lead of 0.4 cm thick, 1.0 cm wide, and 5.4 cm long. The effective grain misalignment angle, phi(eff), was around 10 degrees, calculated from its I-c (B//bar surface) and I-c (B perpendicular to bar surface) curves by using 2D model. For comparison, the average grain misalignment angle, phi(av), found in microstructure using SEM, was measured by pole figure. The obtained results were in agreement with the effective grain misalignment angle phi(eff). The phases and microstructure were analyzed by XRD and SEM.