PRODUCTION OF BISMUTH-BASED OXIDE SUPERCONDUCTOR

摘要

PURPOSE:To obtain an oxide superconductor having uniform and high critical current density and free from cracks and voids by heat-treating mixed oxide raw materials for a Bi-based oxide superconductor under a specific condition, partially melting the heat-treated oxide and crystallizing the product. CONSTITUTION:A bismuth-based oxide superconductor is produced by the following procedures including a partial melting process. A mixture of raw material oxides is heat-treated by maintaining at 850-880 deg.C for 2-30hr. The heat-treated oxide is heated to a partial melting temperature at a heating rate of <=10 deg.C/hr and the partially molten material is crystallized. The starting raw material is preferably incorporated with silver or a silver compound. Especially in the case of producing a Bi-based superconductor having thick Bi-based superconducting layer (>=1mm in contrast with about 100mum to 1mm of the conventional superconducting layer), the addition of an Ag compound is extremely effective because of the synergistic effect of the heat-treatment and heating- rate conditions of the mixed raw material oxide and the addition of the Ag compound to the mixed raw material oxide.