NEW CHEMICAL PINNING CENTER FROM URANIUM COMPOUND IN MELT-TEXTURED YBCO

YBCO, with varying amounts of added uranium up to 0.8% by weight, has been melt-textured. The added U forms a stable compound with Y, Ba, Pt , and O. This compound is well dispersed in the Y-123 matrix in the fo rm of small deposits, less than or equal to 0.3 mu m in diameter. J(C) , measured at 77K in single melt-textured grains 2cm diameter x 0.8cm, increases monotonically with the percentage of U, from 10300 A/cm(2) without U to 17000 A/cm(2) with 0.8% of U. T-C and flux creep are cons tant for the same range of added U. No irradiation is used.