An optimum heating program for fabricating MTG Bi1.6Pb0.4Sr2Ca2Cu3Oy superconductors

Abstract

Following our recent report on the successful fabrication of “stationary” MTG Bi1.6Pb0.4Sr2Ca2Cu3Oy pellets in a simple tube furnace, we have tried many heating programs with various “crystal growth starting temperatures”, Ts, and sintering temperatures, Te; the samples are sintered for 20–40 h before quenching in air. It is found that Ts-Te should be rather narrow to produce good MTG samples, and the typical value of Jc is enhanced from 100 A cm−2 (for a polycrystalline sample) to about 3 × 103 A cm−2 for our good ones. SEM and TEM results indicate that the samples are full of packs which contain highly oriented mica-like layers.