Defect structure and transport properties of nonstoichiometric niobium sulphide

Defect and transport properties of nonstoichiometric niobium sulphide have been studied as a function of temperature (973-1273 K) and sulphur pressure (104 10(4) Pa) using thermogravimetric and marker techniques. It has been shown that the cation sub-lattice of this sulphide is predominantly defected and in high sulphur pressure region cation vacancies and electron holes are the prevailing defects, while at low sulphur pressures interstitial cations and quasi-free electrons are considered predominate. Quantitative analysis of the results of niobium sulphidation kinetics was demonstrated together with chemical diffusion and nonstoichiometry as well as electrical conductivity and Seebeck effect data based on the idea that the proper formula of the discussed sulphide is Nb2 +/- yS3 instead of Nb1+xS2.