HIGH TEMPERATURE SUPERCONDUCTORS WITH IMPROVED CURRENT DENSITIES

THE APPLICATION OF HIGH TEMPERATURE SUPERCONDUCTORS IS SEVERELY LIMITED BY THE LOW CURRENT DENSITIES ACHIEVABLE IN BULK MATERIALS, SUCH AS Y1BA2CU3O(7-X), OR 123 FOR SHORT. THE LARGE CURRENT DENSITIES OBSERVED WITHIN INDIVIDUAL GRAINS (AND IN THIN FILMS) ARE REDUCED BY "WEAK LINKS" AT THE GRAIN BOUNDARIES, CAUSED BY MISALIGNMENT OF THE ANISOTROPIC GRAINS AND BY INSULATING IMPURITY PHASES. SOME OF THE IMPURITIES COME FROM THE DECOMPOSITION OF THE THERMODYNAMICALLY UNSTABLE 123 ABOVE 450 CENTIGRADE. TASK ONE HAS BEEN TO MANUFACTURE AND CHARACTERIZE THE MUCH MORE STABLE 124 COMPOUND, PHASE-PURE AND IN COMMERCIAL LOTS. TASK TWO IS TO HOT DEFORM AND TEXTURE THIS MATERIAL AT CONTROLLED OXYGEN PRESSURES BETWEEN 700 AND 1000 CENTIGRADE AND THEREBY TAKE ADVANTAGE OF THE ANISOTROPY. THE OBJECTIVEIS TO DEMONSTRATE THAT THE RELATIVELY SMALL DEFORMATIONS REQUIRED TO IMPROVE CURRENT DENSITIES ARE COMPATIBLE WITH THE MANUFACTURE OF SIMPLE CYLINDRICAL SHAPES. SUCH SHAPES COULD HAVE IMMEDIATE MILITARY AND COMMERCIAL USES IN EMP SHIELDS, HIGH FIELD MAGNETS, MOTORS, MAGNETIC BEARINGS, AND LEVITATED TRAINS.