CONTRIBUTIONS TO THE GELLING PROCESS IN THE BI-SR-CA-CU-O SYSTEM, VIAACETATE ROUTE

Metal acetates represent suitable precursors in the sol-gel method. Ge nerally, acetates are used in multicomponent systems with alkoxides or other carboxylic salts. However, Bi-Sr-Ca-Cu-O superconductors have b een obtained by the sol-gel method starting only from acetate mixture. This work was intended to study the gelling process of acetates invol ved in the formation of bismuth-based superconducting phases, both ind ividually and in the bi- and multicomponent systems. Probably, copper acetate is mainly responsible for the gel formation in these systems. The gelling process was monitored by measuring the pH, density and vis cosity changes. The gels obtained were characterized by UV-VIS and IR spectra, DTA/TGA and powder X-ray diffraction.