THE ROLE OF URANIUM, WITH AND WITHOUT IRRADIATION, IN THE ACHIEVEMENTOF J(C)-APPROXIMATE-TO-300000-A-CM(-2) AT 77 K IN LARGE GRAIN MELT-TEXTURED Y123

The addition of uranium to large single grains of Y123 improves J(c), prior to irradiation, by over 80%. Observations on the U chemistry and microstructure studies are presented. Irradiation with thermal neutro ns, to fission the U235 component, results in further increases in J(c ). Total increases of J(c) by factors of, e.g. > 30 at 77 K, 0.25 Tesl a, and > 20 at 50 K, 10.0 Tesla, result. Values of J(c) of, e.g. 29000 0 A cm(-2) at 77 K, 0.25 Tesla, and 1 million A cm(-2) at 50 K, 0.25 T esla, result. T-c is reduced by 0.5 K and creep rate is increased by 1 /5. The chemical and irradiation effects are multiplicative and neithe r is yet optimized. (C) 1998 Elsevier Science S.A. All rights reserved .