Critical Current Density and Meissner Effect of Sintered Ba₂YCu₃O_y

Abstract

Critical current densities and Meissner signals of sintered Ba₂YCu₃O_y were measured. The sample cut in water for the measurements have a small critical current density of 3 A/cm² at 77K and a large Meissner signal of 23% at 83K to the perfect flux expulsion. With a thermal annealing, the critical current density increased to 400 A/cm², but the Meissner signal was almost same(19%). The Meissner signals show that the volume fraction of the superconducting phase does not change with the annealing. Therefore, the increase of the critical current suggests that the connections among grains are developed with annealing.