ENHANCEMENT OF CRITICAL CURRENT-DENSITY IN YBA2CU3OX SUPERCONDUCTOR BY MECHANICAL DEFORMATION

The critical current density of melt-textured YBa2Cu3Ox superconductor has been enhanced by mechanical deformation at a high temperature. Hot deformation at 45-degrees to both the slip plane (001) and the slip directions [100]/[010] has resulted in a high density of dislocation loops and stacking faults. The deformed samples are found to exhibit a critical current density (J(c)) at H parallel-to c-axis as high as that at H parallel-to a-b plane at 1.5 T and 77 K. A J(c) of 35300 A/cm2 has been achieved at H parallel-to c (1.5 T and 77 K) which is twice as high as that observed in undeformed samples. The enhanced J(c) in this magnetic field orientation is attributed to pinning by the defects created by mechanical deformation. This pinning mechanism is found to be effective over a wide angle between the magnetic field and the a-b plane and thus results in a marked reduction in the critical current anisotropy.