CRITICAL CURRENT CHARACTERISTICS IN SUPERCONDUCTING Y-BA-CU-O PREPARED BY THE MELT PROCESS

Critical current densities in superconducting Y-Ba-Cu-O specimens with different sizes of 211 particles prepared by the melt process were measured under various magnetic fields and temperatures. Discussion is given on the flux pinning properties by 211 particles and background pinning centers. At temperatures above 60 K, 211 particles are expected to be dominant pinning centers. A rapid degradation of the critical current density with elevating temperature at low temperatures below 25 K seems to be attributed to weak links in specimens.