Effect of Cooling Process on Critical Current Density of Bi-2223/Ag Superconductive Tapes Prepared by Dip-Coating

摘要

In this paper, effect of the cooling process is examined for the superconductive properties of high T_c Bi-2223/Ag tapes prepared by dip-coating. The short tapes are cooled after the isothermal heat treatment at a controlled temperature profile, which can refine the microstructure. The cooling rate and the slow cooling range are varied, showing that the optimum condition is found where the enhanced J_c is obtained compared to that of normal furnace cooling. Contrarily, T_c did not show an optimum under this condition hut increased monotonously with a decrease in the cooling rate and an increase in the slow cooling range. From phase identification, microscopic observation, and quantitative analysis, the microstructure formation in the polycrystalline oxide layer during this process and its relation to these properties are discussed.