Defect concentration and their mobility in nonstoichiometric manganous sulphide

Deviations from stoichiometry and chemical diffusion in metal-deficient manganous sulphide have been studied as a function of temperature (700–1273 K) and sulphur activity (10−1–104 Pa) using direct thermogravimetric technique. It has been shown that in agreement with the defect model, the nonstoichiometry of Mn1−yS is a simple power function of sulphur activity and can be described by the following equation:y=4.5·10−2pS21/6exp−41.7 kJ/molRTThe vacancy diffusion coefficient, being the direct measure of defect mobility, has been found to be independent of their concentration, and is the following function of temperature:DV=1.97·10−2exp−83.4 kJ/molRT