Novel Processing of Hts Based Conductors

Abstract

Conductor development is one of the major long term goals in high temperature superconductor research. In this paper we report on two promising processing technologies that have been utilized to produce superconducting HTS conductors. First, melt spun YBa₂Cu₃O₇ fibers rapid thermal processed for 1-8 sec at 950 to 1075°C have T_c’s to 92 K, J_c’s to 1100 A/cm² and the orthorhombic twinned morphology typical for high quality YBa₂Cu₃O₇ A processing matrix of time, temperature and composition for these fibers shows that slightly CuO-rich starting compositions give the best results. Second, silver tube encapsulated wires of Bi_1.7Pb_0.3Sr₂Ca₂Cu₃O₁₀ have been made by extrusion, wire drawing and cold rolling. The resulting tapes show orientation of the crystallites, zero resistance up to 100K and improved magnetic hysteresis above 50 K. The combination of mechanical reprocessing and extended thermal anneals near 850°C appears to significantly improve these materials.