Using new solid sources for controlling the bulk size expansion and improving the performance of single-grain Y–Ba–Cu–O bulk superconductors

Abstract

Two new solid sources of compositions Y 2 O 3 + 1.15BaCuO 2 + 0.1CuO and Y 2 O 3 + 1.3BaCuO 2 + 0.2CuO were employed in the 011-type infiltration growth (011-IG) technique for fabricating single-grain Y–Ba–Cu–O bulk superconductors, which corresponded to 5 mol% Ba 3 Cu 5 O 8 and 10 mol% Ba 3 Cu 5 O 8 rich samples respectively. The results indicated that, the natural size expansion phenomenon observed in 011-IG-processed bulks was controlled to some extent via the Ba 3 Cu 5 O 8 addition, and the porosity in sample structure was reduced with the increasing Ba 3 Cu 5 O 8 amount. The scanning electron microscope measurement showed that, large amount of nano-precipitates were observed in the normal 011-IG-processed sample, but with the addition of Ba 3 Cu 5 O 8 , the number of nano-precipitates declines seriously. Because the 5 mol% Ba 3 Cu 5 O 8 rich sample can realize both low porosity and presence of nano-precipitates, it exhibits the highest properties of levitation force and zero-field J c , thus the composition Y 2 O 3 + 1.15BaCuO 2 + 0.1CuO can be considered as a more optimized solid source for obtaining higher superconducting properties in the 011-IG technique.