Infiltration-growth processing of NdBa2Cu3O7-δ superconductor

NdBa2Cu3O7-delta (Nd-123) superconductor has been processed to obtain a highly textured microstructure with micrometer-sized spherical Nd4Ba2Cu2O10 (Nd-422) inclusions through a process that involves the infiltration of liquid phases into a shaped preform followed by its slow cooling through the peritectic formation temperature of Nd-123. The process was carried out in high-purity argon (maximum of 4 ppm of oxygen) to reduce the formation of low-T-c solid solutions. A major advantage of the process is that it minimizes the possibility of Nd-422 coarsening in the liquid. The result is a very uniform distribution of nearly spherical Nd-422 inclusions with 80% of the particles having a diameter less than 1 mu m, in the highly textured Nd-123 matrix. Since the present process eliminates shrinkage and large hollows within the interior of the samples, it can enable the fabrication of 3-dimensional complex-shaped objects with goad dimensional tolerance and high J(c) for applications. The critical current densities in the Nd-123/Nd-422 composites have been measured and the values obtained are discussed in the context of the microstructure of the material.