Grain Orientation and Superconducting Properties in the Bi-Sr-Ca-Cu-O System

Abstract

The Bi-Sr-Ca-Cu-O oxide superconductor has a strong anisotropy in physical and mechanical properties. Therefore, magnetic properties may change with the rate of grain orientation in a polycrystalline sample. In this report, we have studied the relation between ΔM, which is the difference of magnetization of the irreversible M-H curve, and the rate of grain orientation, and their magnetic field dependences of the Bi₂Sr₂Ca₂Cu₃O_x ceramics. To have various rates of grain orientation, the hot-forging was performed for the sintered specimens, and X-ray diffraction patterns showed the change of the rate of grain orientation. Measurements of M-H curves were performed using VSM at 77K. The ΔM remarkably changed with the rate of grain orientation at low field, but the change of it became slow with the increase in the magnitude of the magnetic field probably because of the flux creep at the grain boundaries.