Synthesis and superconducting properties of c-axis aligned, single-domain NdBCO/Ag, melt-processed superconductors

We prepared c-axis aligned, large single-domain Nd-Ba-Cu-O (NdBCO) bulk superconductors with the addition of Ag2O by the melt-processing technique under a flowing Ar gas atmosphere using Ag-free NdBCO as seed crystals. The melt-processing condition has been elaborated by varying the contents of Ag2O and CeO2, and the molar ratio of Ba to Cu. We successfully synthesized c-axis aligned, single-domain samples, free from serious cracks or weak links, 30 mm in diameter and 13 mm in thickness in the range of 15-20 wt% Ag2O, 0-0.5 wt% CeO2 and 0.706-0.76 for the Ba to Cu ratio. The largest trapped field of these NdBCO samples was 1.23 T at 77 K and 7.0 T at 42 K, while fracturing of the sample occurred at a further lower temperature. We found that the field trapping performance of the present NdBCO/Ag samples is almost the same as that of our previously reported SmBCO/Ag samples, but the critical stress of fracturing was smaller for NdBCO/Ag.