PHASE EQUILIBRIA AT HIGH TEMPERATURES

Abstract

The wide variety of metal sulfide structures and their accommodation of atomic substitution, non-stoichiometry and metal-metal (M-M) and ligand-ligand interactions allows for diverse physical, chemical and electronic properties. The energy band structure of 3d transition-metal sulfides, in particular, is strongly influenced by the covalence of metal-S bonds, which results in hybridization of S 3p and metal 3d bonding states and direct or indirect M-M bonding interactions in favorable cases. Differences in the phase relations of isostructural metal sulfides are often attributable to subtle changes in electronic states. The literature on metal sulfi de phase relations relevant to the earth sciences is very extensive and could not possibly be summarized in a single chapter. Therefore, following Craig and Scott (1974), this chapter focuses on the base metal (Fe, Co, Ni, Cu, and Zn) sulfides, with the literature for other metal chalcogenides and pnictides and some sulfosalts summarized in a single table.