Precursor powder influence on melt processing of high critical current BSCCO rods

The influence of the starting powder characteristics on the phase formation , microstructure and J(c) (77 K) of Bi-2212 monoliths fabricated by the LFZ method has been analysed. Attractive transport critical current values (ca 90 A in approximate to 1.8 mm diameter rods) have been measured on samples obtained from practically any of the precursors studied, that is prereacte d 2212, mixtures of 2201 and sub-micrometre sized CaCuO2 or, alternatively, a mixture of the corresponding commercial oxides and carbonates. The latte r method reduces significantly the processing procedure related to the use of chemically derived starting precursors or to the attainment of the 2212 phase in the precursor at a high purity level. The selection of particular precursor mixtures affects the final textured superconductor properties onl y to a limited extent. These appear to be related to the influence of the p recursors on both, the melting and solidification processes, associated in turn with their modification of the reaction pathway towards 2212 formation .