Order-disorder phenomena of cationic vacancies in a vanadium sulphide, V 5S 8

Abstract

A vacancy order-disorder transition in a vanadium sulphide, V 5S 8, has been investigated by an in situ experiment at high temperatures using polychromatic X-ray diffractometry. Vanadium vacancies, which are orderly arranged at room temperature in every second metal layer of the NiAs-type structure, are disordered in both intra- and inter-layers at elevated temperatures below about 800 °C. At this temperature, the intra-layer disordering is completed, to transform to a high-temperature phase. This has probably a trigonal symmetry with complete intra-layer disordering whilst the interlayer order is still partially maintained.