Effects of a controlled over-pressure process on the critical current properties in Bi-2223tapes

Abstract

Critical current properties in Bi-2223 superconductor were investigated in detail forsilver-sheathed tapes fabricated by the usual process in a normal pressure, the previouscontrolled over-pressure (CT-OP) process and the recently improved CT-OP process at the finalheat treatment. It was shown that the critical current density, the irreversibility field and then-value were remarkably improved by application of the CT-OP process. The results wereanalysed using the flux creep-flow model to seek the reason for the improvements. It wasfound that the grain connectivity and the flux pinning strength were improved by theprevious and recent CT-OP processes, respectively. The possibility of further improvementsof the critical current properties in Bi-2223 tapes is discussed.