Defect mobility in non-stoichiometric samples was studied at 1073 to 1273K, for S activities of 0.0001 to 1Pa, by using a microthermogravimetric re-equilibration technique. It was shown that the chemical diffusion efficient, and thus the mobility of defects in the sulphide, was more than 3 orders of magnitude lower than that in other transition metal sulphides. This result was considered to be the first experimental proof of the hypothesis that the protective properties of the sulphide resulted from an unusually low mobility of defects in the sulphide of Nb.

On the Defect Mobility in Niobium Disulphide. Z.Grzesik, S.Mrowec, J.Dąbek: Solid State Phenomena, 2000, 72, 29-34