The ceramic disulphide was equilibrated at ambient S-phase partial pressures, PS2, of 10 to 1000Pa. After a step change in PS2 to a new value, the equilibration kinetics were monitored by measuring the electrical conductivity. Application of the solution of Fick's second law (with the initial conditions of no concentration gradient in specimen and the boundary condition of constant surface concentration) to the kinetic data gave the chemical diffusion coefficient. The chemical diffusion coefficient determined at 1273K was 3.20 x 10−7cm2/s, and was found to be independent of the S-phase partial pressure.

Chemical Diffusion in Molybdenum Disulphide. M.Potoczek, K.Przybylski, M.Rekas: Journal of Physics and Chemistry of Solids, 2007, 68[4], 564-9