Critical current density in YBa 2Cu 3O 6+ x added with perovskite type impurity

Abstract

Improvement of the critical current density of YBa 2Cu 3O 6+ x has been attempted by adding perovskite ABO 3 type oxides (A=Ba, Ca, Sr, and B=Sn, Zr, Ti). Of those, only two phases, BaSnO 3 and BaZrO 3 were found to be stable after nine kinds of mixture were sintered for a long time at 1223 K. AC magnetization measurements were carried out at temperatures between 15 and 90 K and the grain-boundary and intragrain critical current densities were evaluated. A very high intragrain critical current density was attained at a temperature above 50 K for the specimens including BaSnO 3 or BaZrO 3 fine particles, which were observed to distribute homogeneously and semi-coherently within the matrix. The critical current density in the grain-boundary region was found to be the same in magnitude as the value determined by the four-probe DC technique, which was fairly less than the intragrain critical current density.