Abstract
Bi-2212 superconductor is known as one of the candidates for practical superconducting wires. The “partial melting and slow cooling process” realizes a well-oriented microstructure, good connectivity between superconducting grains and excellent critical current density below 30K. Many investigations of phase changes during heat treatment have been carried out and the results have been quite helpful for controlling the microstructure, thus improving superconducting properties. There are three factors which affect superconducting properties: oxygen concentration in the atmosphere, composition of the superconducting powders and heat-treatment schedule. The highest Jc value, approximately 5×105A/cm2 at 4.2K and 0T, was achieved using the powder-in-tube technique and has been applied to produce an insert magnet of a high-field magnet. The issues which remain to be solved are the introduction of effective pinning centers above 30K and improvement of the mechanical strength and homogeneity of long wires.
