Effect of precursor phase assemblage on densification and critical current density of (Bi,Pb)-2223 superconductor

Studies on (Bi,Pb)-2223 superconductors prepared using precursors with different partial reaction levels have shown that their densification, microstructure and transport critical current density (J(C)) are highly dependent on the reaction level/phase assemblage of the precursor used. Less reacted precursors yielded samples with high 'retrograde' densification, large grains of high quality and fairly good J(C). The retrograde densification, characteristic of (Bi,Pb)-2223 superconductors, can be completely avoided by the use of fully reacted precursors. However, the J(C) normalized with respect to density is found to be much higher for samples prepared from less reacted precursors than those from fully reacted ones. The finding opens up an avenue for development of high density, high J(C) bulk products by repeated compaction and sintering of less reacted precursors without regrinding. (C)2004 Published by Elsevier B.V.