Homogenizing field-trapping capabilities of bulk Y-Ba-Cu-O superconductors fabricated using Ba-Cu-O oxide substrates for practical applications

We employed Ba-Cu-O substrates for fabrication of bulk Y-Ba-Cu-O superconductors using the top-seeded melt-growth method. There were several advantages of using a Ba-Cu-O substrate as compared to conventional substrate materials such as MgO, ZrO₂, Al₂O₃, RE123 (RE = rare earth) and RE211. The Ba-Cu-O substrate avoided crystallization from the substrate, suppressed liquid loss and scarcely reacted with the precursor. Furthermore, the introduction of large-sized cracks into a grown bulk was greatly suppressed by propagation along the interface between the grown bulk and the substrate. We were able to obtain bulk Y-Ba-Cu-O superconductors with uniform trapped magnetic field distributions and equal maximum trapped field values on both top and bottom surfaces, which indicates that the field-trapping capabilities were homogenized along the c-axes of the bulks fabricated on the Ba-Cu-O substrates.