Thermal behavior of alpha-Ba(FeS2)(2) and AgFeS2: quasi-unidimensional and3D network compounds prepared from ion-exchange on the same precursor

Thermal behavior of AgFeS2 and alpha-Ba(FeS2)(2) were studied under air atm osphere. Decomposition products of AgFeS2 are Ag2S, FeS2 (pyrite form), Ag2 SO4, alpha-Fe2O3 and metallic silver. a-Ba(FeS2)2 decomposes to pyrite, alp ha-Fe2O3 and BaSO4. We propose that metallic sulfide formation on the initi al step of the decomposition of these compounds is related to the packing o f the metallic ions with sulfur and, hence, with metal-sulfur distances in the original material. Morphological information about AgFeS2 and alpha-Ba( FeS2)(2) are presented for the first time. (C) 1999 Kluwer Academic Publish ers.