SUPERCONDUCTIVITY OF YBA2CU3O7-X BY ADDITION OF REACTIVE FINE POWDERS

We report a new method for introducing pinning centers by partial melting processing using reactive fine powders, such as SiC, SiO2, Al2O3, and ZrO2. Since this method lowers processing temperature, it may become a useful technique for the production of high-J(c) metal-sheathed tapes and wires. YBCO powders were mixed with 25 mol% SiC powder of 0.3-mu-m, sintered at 980-degrees-C for 15 min and cooled at 3-degrees-C/h under flowing oxygen gas. The obtained samples show prominent grain growth and reacted phases (Y2BaCuO5, Ba2SiO4) which are of submicron size and uniformly dispersed in the YBCO matrix. Magnetic measurements show the improvement of the critical currents (over 7500 A/cm2 at 77 K 0.04 T), and the sample shows the so-called fishing behavior at 77 K. It seems that the reacted phases (Y2BaCuO5, Ba2SiO4) work as effective pinning centers.