Refinement of Nd-422 phase trapped in a Nd_1+δBa_2-δCu₃O_7-γ superconducting matrix

The possibility of controlling Nd-422 phase dimension and morphology, both in the partially melted state and in the final superconducting matrix, was investigated. Nd-Ba-Cu-O samples were prepared by the melt powder melt growth (MPMG) technique. Precursor materials containing Nd as either Nd₂O₃ or Nd-422, formed during precursor quenching, were used. The role of Pt in Nd-422 refining was analyzed. The effect on Nd-422 nucleation and growth, of stoichiometries with increasing Nd-422 molar excesses (0%, 10%, 20%, and 40%) combined with different heating processes, up to the partially melted state, were examined. Uniformly distributed needle-like particles (1 μm diameter and 10-15 μm length) were obtained at 1120°C and resulted in a further refined distribution trapped in completely processed samples.