Critical current density enhancement by phase decomposition of YBa 2Cu 4O 8 into YBa 2Cu 3O 7−σ and CuO

Abstract

Bulk YBa 2Cu 4O 8 (Y-124) is prepared from YBa 2Cu 3O 7−σ (Y-123) and CuO by a powder-metallurgical method. The superconducting features of the Y-124, in particular critical current densities and activation energies, are measured resistively using a four-probe technique and magnetically using a Faraday magnetometer. In a second step the Y-124 is decomposed at high temperatures. The intragranular critical current density is measured at different annealing times, t A, in order to determine and discuss the characteristics of the j c( t A) curves.