Improvement of characteristics of Bi system superconducting sintered bodies

Since the discovery of oxide superconductors, in order to heighten the critical current density, various methods have been tried for the raw materials and the processing method. As for Bi-2223 phase, the research and development have been actively carried out as the critical current density can be improved by forcibly orienting crystals applying external force to the plate crystals, there is no anxiety about its supply in view of the resource, and the cost can be controlled. In this research, the reduction of impurities and the optimization of the heat treatment conditions for the calcined powder were studied in order to make the sintered body of Bi-2223 phase that has high critical current density. The experimental method is described on the preparation of samples and the evaluation of the samples. As the experimental results, the properties of the calcined powder and the sintered body are reported. By carrying out drying in reduced pressure atmosphere for removing solvent after crushing in calcined powder production process, the amount of carbon was able to be reduced to below 300 ppm. It was able to be confirmed that by changing the calcination temperature of calcined powder, the rate of content of the substances that did not react changed. (K.I.)