Oxygen self-diffusion in non-stoichiometric rutile TiO2$minus;x at high temperature

Abstract

Abstract Oxygen self-diffusion coefficients, D 0 ∗ , were determined in TiO 2− x at 1373 K (8.4 × 10 −3 ⩾ mx ⩾ 5 × 10 −4 ). D 0 ∗ increase with increasing non-stoichiometry. It is concluded that oxygen vacancies contribute 20% to the non-stoichiometry at x=8.4×10 −3 and it is suggested that both singly and doubly ionized vacancies are present in presetn in the aproximate the ration of 1–2. The interpretation of the results also indicate that the complete description of defect structure includes interstitial titanium ions with three positive effective charges as major defects for the more reduced oxide whereas interstitial titanium ions with four effective charges may become important in almost stoichiometric TiO 2 .