ENHANCEMENT OF TRANSPORT CURRENT DIESITY IN YBA2CU3O7-X FIBERS USING LASER ZONE REFINEMENT VERY LARGE SCALE INTEGRATION TECHNOLOGY

SINCE THE NEW CERAMIC SUPERCONDUCTORS BROKE THE LIQUID NITROGEN BARRIER WITH THE DISCOVERY OF THE YBA(2)CU(3)O(7-X) (123) SUPERCONDUCTORS, HAVING A CRITICAL TEMPERATURE (T(C)) IN THE MID-NINETIES KELVIN, MUCH WORK HASBEEN DEVOTED TO THEM. SURPRISINGLY, THE TRANSPORT CURRENT DENSITIES (J(C)) HAVE REMAINED STUBBORNLY LOW IN THE BULK-PROCESSED POLYCRYSTALLINE FORM OF THESE MATERIALS: THIS IS BELIEVED TO BE DUE TO WEAK-LINK BEHAVIOR. THESE WEAK-LINKS HAVE TWO POSSIBLE ORIGINS; FIRSTLY, THE PRESENCE OF NON-SUPERCONDUCTING PHASES AT THE GRAIN BOUNDARIES AND, SECONDLY, THE INTRINSIC ANISOTROPY OF THE SUPERCONDUCTIVITY IN HIGH T(C) SUPERCONDUCTORS. IN THIS PHASE I PROJECT, CONVENTIONAL ZONE REFINEMENT TECHNIQUES WILL BE USED TO FABRICATE 123 CERAMIC FIBERS WITH CLEAN, TEXTURED GRAINS. RODS OF THE 123 MATERIALS WILL BE LASER ZONE REFINED AND STUDIED IN DETAIL TO DETERMINE THE EFFECTS OF THIS PROCESS ON THE TRANSPORT CRITICAL CURRENTS IN 123 SUPERCONDUCTING COMPOSITES.