J(C) ENHANCEMENT OF YB(A)(2)CU(3)O(7-X) FIBERS USING LASER ZONE REFINEMENT

TREMENDOUS EXCITEMENT AND INTEREST HAS BEEN GENERATED IN RECENT MONTHS OVER THE DISCOVERY OF THE YBA(2)CU(3)O(7-X) ("123"), LIQUID NITROGEN SUPERCONDUCTORS. HOWEVER, THIS EXITEMENT HAS BEEN TEMPERED BY THE INABILITY TO ACHIEVE LARGE TRANSPORT J(C)'S IN BULK-PROCESSED POLYCRYSTALLINE MATERIALS BECAUSE OF WEAK LINK BEHAVIOR. THESE WEAK LINKS HAVE TWO POSSIBLE ORIGINS; FIRSTLY, THE PRESENCE OF NONSUPERCONDUCTING PHASES AT THE GRAIN BOUNDARIES AND SECONDLY, THE INTRINSIC ANISTROPY OF THE SUPERCONDUCTIVITY IN THE HIGH T(C) SUPERCONDUCTORS. IN THIS PHASE I PROPOSAL CONVENTIONAL ZONE REFINEMENT TECHNIQUES WILL BE USED TO FABRICATE "123" CERAMIC FIBERS WITH CLEAN, TEXTURED GRAINS. WE WILL LASER ZONE REFINE RODS OF THE "123" MATERIALS FABRICATED AT SUPERCON INC., AND STUDY IN DETAIL THE EFFECTS OF THIS PROCESS ON THE TRANSPORT CRITICAL CURRENTS IN YBA(2)CU(3)O(7-X) SUPERCONDUCTING COMPOSITES.