Superconducting properties of Y-Ba-Cu-O bulk with BaSnO3 addition

Abstract

Dispersion of non-superconducting phase particles is commonly employed in melt textured REBa2Cu3O7-δ (RE123; RE: rare earth element) bulk superconductors in order to improve the critical current density. It has been clarified that the interfaces of RE2BaCuO5 (RE211) and RE123 matrix contribute to the flux pinning, and therefore, the critical current density can be enhanced due to the refinement of RE211 particles. In recent years additions of RE2Ba4CuMOy (M=Zr, Nb, Ta, Mo, U, Sn, and Re) particles have been investigated in an attempt to improve the pinning performance. While the common particle size is around 1-5 μm for the RE211, the size of RE2Ba4CuMOy particles is much finer and typically 50∼300 nm, implying that the pinning may be improved with the dispersion of RE2Ba4CuMOy particles. In this study, we have studied the effects of the BaSnO3 addition to Y2BaCuO5 (Y211) powders. It was found that two different compounds of Y2Ba4CuSnOy and Y2BaCuO5 phase particles were co-produced by adding BaSnO3 to Y211. These powders were added to the precursor and subjected to the melt-textured process to grow bulk Y-Ba-Cu-O superconductors of 20 mm diameter with the top-seed melt growth process. The finished bulk samples were observed with optical microscopy and subjected to trapped field measurements with Hall sensors. The trapped field measurements showed that BaSnO3 addition was effective in improving the field trapping ability.