Spray dried Pt-doped Nd-Ba-Cu-O precursor powder for seeded peritectic processing of large superconducting grains

Large grain Nd-Ba-Cu-O has significant potential for application in bulk superconducting 'permanent magnet' engineering devices. This study describes the preparation of Nd-Ba-Cu-O precursor powder by spray drying and subsequent calcination for the growth of large grains using a seeded peritectic solidification technique. Precursor powder prepared by this method has been used to fabricate large Nd-Ba-Cu-O grains which exhibit good growth morphologies. Surface roughening associated with a continuous phase transformation that occurs in the precursor bodies prior to and during melt processing has been identified as a source of inhomogeneity in the grain growth morphology. This may be avoided by calcining the precursor powders at high temperature for a short period of time to yield only the desired crystalline and structural phases. (C) 1999 Published by Elsevier Science S.A. All rights reserved.