The structural behaviour and physical properties of some MX 2 (Cdl 2 type) layered crystals

Abstract

The layered materials of the MX 2 type cover a wide range in regard to physical properties. As for example, in relation to the electrical behaviour, these materials vary from dielectric through semiconductor to metal or semimetal like in their characteristics. A point of particular interest and of potential importance from the point of view of the application in solid state devices is the variation of the physical properties from polytype to polytype of the same material. Thus, the electronic band gaps of the PbI 2 and SnS 2 layered semiconductors vary considerably with the polytype periodicity. This unique behaviour makes these materials potential candidates for use in devices like variable band gap solar cell devices or as wide range infrared detectors. The layered materials like titaniumdisulphide form solid state storage battery materials. Because of the obvious importance, the MX 2 type layered materials will continue to obtain increasing attention in regard to the studies embodying the structural and physical behaviour and also in regard to the explorations seeking to establish their applications in solid state devices.