Improvement of the superconducting properties in (Nd, Sm, Eu)-Ba-Cu-O using melt-quenched precursors

We have studied the effect of precursor preparation methods on the superconducting properties of (Nd, Sm, Eu)-Ba-Cu-O melt-textured in 1% O₂-Ar. X-ray diffraction analyses confirmed that melt-quenching was effective in suppressing the formation of RE rich RE_1+xBa_2-xCu₃O_y precursor powders compared to a sintering method, and thus resulted in a sharp superconducting transition with an onset T_c exceeding 94.5 K. A clear secondary peak effect was observed in the magnetization curves, which shows that the field induced pinning is active like the other RE-Ba-Cu-O (RE; Nd, Sm, Eu, Gd). One can conclude that poor superconducting properties of (Nd, Sm, Eu)-Ba-Cu-O obtained in the previous reports are not intrinsic to the system but to an unoptimized precursor preparation method.