The Influence of Starting Temperature of Quench upon the Critical Current Density of Bi₂Sr₂CaCu₂O_y Using Partially Melting Method

Abstract

We prepared Bi₂Sr₂CaCu₂O_y polycrystalline superconductor by partially melting method in HNO₃ or solid state method and investigated the influence of precursor condition and quench temperature upon the critical current density. The best starting temperatures of quench were 650°C in HNO₃ method and 500°C in solid state method. In these conditions, critical current densities were 198A/cm² in the former and 102A/cm² in the latter. We found that starting temperature of quench influences the break of junctions between grains by thermal contraction and condition of precursor influences the occuring defect and grain growth in melting process.
It is important to select the best conditions of quench and precursor to prepare Bi₂Sr₂CaCu₂O_y polycrystalline superconductor with high critical temperature and density by partially melting and quench method.