Grain-Growth Enhancement in the YBa sub 2 Cu sub 3 O sub (7-delta) Superconductor by Silver-Oxide Doping

The addition of silver-oxide has been found to accelerate the decomposition and melting of the Y-Ba-Cu-O superconductor. The doped sample exhibits, after sintering near 980C, morphology of very large, stacked-plate grains for the YBa sub 2 Cu sub 3 O sub (7-delta) phase and the presence of decomposition products. By contrast, doping with metallic silver does not noticeably induce such an effect. The enhanced grain growth in the Ag sub 2 O-doped superconductor is most likely to be the main cause of the previously reported increase in magnetization hysteresis and the superconductor suspension effect at 77K. Beneficial effects of the addition of metallic silver such as enhanced oxygen diffusion and extremely low contact resistance are also discussed.