Ba-Cu-O系酸化物支持材を用いた超電導バルク体の品質向上に関する研究

We employed Ba-Cu-O substrates for the fabrication of bulk Nd-Ba-Cu-O superconductors using the top-seeded melt-growth method. There were several advantages for the use of Ba-Cu-O substrate compared to conventional substrate materials such as MgO, ZrO2, Al2O3, RE123 and RE211 (RE: rare earth). The Ba-Cu-O did not react with the precursor and minimized the loss of liquid. Accordingly, the introduction of large-sized cracks was suppressed. We also found that Tc values were high at the bottom regions, which was ascribed to the beneficial effect of Ba-Cu-O in suppressing Nd/Ba substitution. As a result, we could obtain bulk Nd-Ba-Cu-O superconductors that exhibit fairly good field-trapping capabilities even at the bottom surfaces.