Solid State Transition Metal Sulphides

Abstract

From mineralogy and geology to theoretical chemistry and catalysis, transition metal sulphides occupy important positions in many fields. Pyrite, a naturally occurring form of iron disulphide (FeS2) known also as Fool’s Gold, is one of the three largest commercial sources of elemental sulphur, which in turn is vital to the world economy as a starting material for the single most important industrial chemical, sulphuric acid [1]. Sphalerite (ZnS) and cinnabar (HgS), common sulphide minerals, are the largest sources of zinc and mercury, respectively [1]. Molybdenite, MoS2, is the principal ore of molybdenum, although most molybdenum is obtained as a byproduct in the production of copper via formation of MoS2 as an intermediate [1]. Sulphide minerals are, in fact, the source of most of the world’s non-ferrous metals [2]. Geologically, pyrite and other sulphide minerals serve as indicators of how and when rock formations were created; troilite, FeS, is a rare mineral on earth but a common one on meteorites and lunar rocks; this highlights the differences in their origins [2, 3]. Binary transition metal sulphides, with their intriguing electrical and magnetic properties, are being explored for device applications, such as semiconductors and magnetic recording materials [2]. Another fascinating phenomenon found in some binary sulphides, including MoS2, is that of charge-density waves, which in the last twenty five years has been the subject of much theoretical study and has led to a better understanding of chemical bonding in general [4–7].