THE EFFECT OF ANNEALING ON STACKING-FAULTS AND J(C) VALUES OF PMP PROCESSED YBCO

Highly textured YBCO bulk materials with dense stacking faults were pr epared by the powder melting process (PMP). We re-annealed the samples at temperatures between 800 degrees C and 900 degrees C to reduce the stacking faults in YBa2Cu3Oy (123) crystals. The microstructural char acteristics of these samples were investigated by SEM and TEM, and the ir critical current densities were estimated from magnetization hyster esis loops. The results indicate that both the density of stacking fau lts and the J(c) values decrease considerably after the reheat treatme nts. The reasons for the elimination of stacking faults by annealing t he specimens at high temperature are discussed.