Fabrication of large grain Nd-Ba-Cu-O by self-seeded melt growth

Large, single grain Nd-Ba-Cu-O (NdBCO) samples containing Nd-422 phase Incl usions have been fabricated successfully using NdBCO self-seeds by two melt processing techniques under reduced oxygen partial pressure. The first tec hnique involves hot seeding where the reed crystal is placed onto the sampl e surface at the peritectic temperature. The second method invloves doping precursor powder with Au and Ag to reduce the peritectic decomposition temp erature of the material. This enables seeding to be achieved by introducing an undoped Nd-123 seed to the sample surface at room temperature, which si mplifies processing significantly. This paper compares the microstructure o f large grain NdBCO samples fabricated by the two techniques including the dependence of growth rate on undercooling, processing atmosphere and the si ze and distribution of Nd-422 in the Nd-123 phase matrix.