PROCESSING CONTROLLED STACKING-FAULTS IN YBA2CU3O7-DELTA AND THEIR EFFECT ON FLUX PINNING

There has been considerable interest in inserting controlled defects in high-temperature superconductors to enhance their flux pinning potential. One means of obtaining controlled defects in the YBa2Cu3O7-delta (Y123) structure is to decompose YBa2Cu4O8 (Y124). However, not only is the decomposition of the Y124 to optimize pinning difficult to control, sintering dense compacts of Y124 is very difficult. It is shown that the addition of 1.2 wt% CuO to Y123 sintered at 830-degrees-C results in evenly spaced 1/6[031] extrinsic stacking faults. These stacking faults have also been shown to increase pinning energy, and are stable to at least to 900-degrees-C. Intragranular J(c), as calculated from the hystersis loops, shows a significantly reduced temperature dependence at high fields. J(c) dropped only a factor of 30 from 2 X 10(6) at 10 K to 6 X 10(4) A/cm2 at 70 K at 1 T.