Chemical diffusion and defect mobility in nonstoichiometric manganous sulfide

Abstract

The chemical diffusion coefficient in nonstoichiometric manganous sulfide, Mn 1− y S, was measured as a function of temperature (1073–1373 K) and sulfur pressure (10 −2 –10 3 Pa) using the electrical conductivity reequilibration kinetic method. It has been shown that the mobility of doubly ionized cation vacancies in Mn 1− y S is independent of their concentration and can be characterized by the following empirical relationship describing the temperature dependence of the defect (vacancy) diffusion coefficient: D V = 1.3 × 10 − 2 exp ( − 76.4 ± 0.5 kJ / mol R T ) Using these data, the activation entropy and enthalpy of defect migration in Mn 1− y S have been calculated: Δ S m =10.4 J/mol deg and Δ H m =76.4±0.5 kJ/mol.