Effect of the addition of depleted UO_2 on the micro structure of melt processed Y-Ba-Cu-O superconductors

摘要

We have investigated the effect of the addition of depleted UO_2 to the microstructure of undoped large grain Y-Ba-Cu-O (YBCO) superconductors and those doped with Pt. It is found that the addition of UO_2 to YBCO promotes the formation of fine uranium containing, non-Y_2BaCuO_5 (Y-211), second phase particles in the YBa_2Cu_3O_(7-δ)(Y-123) matrix. These particles are of approximately spherical morphology and they are typically a few hundred nanometers in diameter. In addition, Pt has no significant effect on refining the second phase in UO_2 containing samples, in contrast with UO_2-free Y-123. Further and uniformly distributed second phase particles are observed in uranium doped melt textured YBCO for the first time by the addition of Y_2O_3, rather than Y-211 to the precursor powders.