Defect mobility in non-stoichiometric material was studied at 873 to 1073K, for S activities of 10-4 to 0.1Pa, by using microthermogravimetric re-equilibration techniques. The chemical diffusion coefficients which were deduced from oxidation and reduction runs were essentially the same; thus clearly indicating that the rate-determining step of the overall re-equilibration process was solid-state diffusion. It was found that the chemical diffusion coefficient did not depend upon the S activity, and could be described by:

D = 3.1 x 10-2 exp[-76(kJ/mol)/RT]

On the Defect Diffusivity in Co9S8. Z.Grzesik: Solid State Ionics, 2001, 141-142, 295-9