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 su perconducting 'permanent magnet' engineering devices. This study describes the preparation of Nd-Ba-Cu-O precursor powder by spray drying and subseque nt calcination for the growth of large grains using a seeded peritectic sol idification technique. Precursor powder prepared by this method has been us ed to fabricate large Nd-Ba-Cu-O grains which exhibit good growth morpholog ies. Surface roughening associated with a continuous phase transformation t hat 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 temperatur e for a short period of time to yield only the desired crystalline and stru ctural phases. (C) 1999 Published by Elsevier Science S.A. All rights reser ved.