Influence of multiple intermediate processing on critical current density and trapped magnetic field in Bi,PSrCaCuO superconductor

Abstract

The influence of a multistep intermediate pressing and sintering process on properties, mainly on transport critical current density ( J c) and trapped magnetic field has been examined in a 2223-phase (Bi 0.9Pb 0.1) 2Sr 2Ca 2Cu 3O 10 polycrystalline superconductor shaped in pellets and a tube. Prepared pellets of an increased density up to 92% theoretical value exhibited an increased degree of texture in the c axis direction and an improved J c(77.3 K) up to 4230 A cm −2 and 1550 A cm −2 at magnetic fields of 0 T and 100 mT, respectively. The J c values increased with the increasing number of pressing and sintering steps ( n) only up to a certain value of n. A higher number of steps resulted in deteriorated J c, probably because of the occurrence of microcracking. The superconducting tube was successfully fabricated using the multiple intermediate pressing and sintering process. The use of the process made possible the increase of trapped and shielded magnetic fields over 20 mT at the temperature of 77.3 K. As for the pellets, the deterioration of J c in the wall of the tube as well as a deterioration of the trapped and shielded magnetic fields were found for higher n.