Measurements were made of the chemical diffusion coefficients for various non-stoichiometries of TiO2-x at 1050C, using a new experimental technique which had various advantages. Firstly, there was no interaction between the sample and the gas phase. Secondly, the measured diffusion coefficients were obtained from initial concentration differences Δx/x which were typically 10−1 between the extremities of the oxide and which almost corresponded to a well-defined non-stoichiometry of the oxide. The results (figures 7 and 8) were critically compared with the literature and interpreted in terms of a major constituent, interstitial Ti3+, responsible for the diffusion. Consequently, oxygen vacancies possibly associated with shear planes in the TiO1.99-TiO1.995 part of the non-stoichiometric domain were expected to be minor defects in this oxide.

Isothermal Transport in TiO2-x. Part II. Chemical Diffusion in TiO2-x. Ait-Younes, N., Millot, F., Gerdanian, P.: Solid State Ionics, 1984, 12, 437-42

Figure 7

Diffusivity of Ti in TiO2 at 1050C as a function of O partial pressure