Sol-gel processing of precursor for high-T-c superconductors: influence ofrhenium on the synthesis of Ba2Ca2Cu3Ox

A sol-gel method for processing precursors of mercury-cuprates is described . It uses the gelification of a solution by acrylamide polymerisation and m ay be applied to concentrated solutions if a proper stabilisation of the ca tions is ensured. The method is described here for Ba2Ca2Cu3Ox and Re0.25Ba 2Ca2Cu3Ox but may serve to other precursors. Barium carbonate contamination is avoided in a large extent and Re-addition even helps by its efficient c ombination at low temperature with barium species. The precursor, with Re, might be handled without complicated precautions. Superconductors have been prepared in this way with an excellent homogeneity and high T-c. (C) 2000 Elsevier Science B.V. All rights reserved.