The self-diffusion coefficient of oxygen was determined for non-reduced and reduced single crystals of rutile at 806C (table 4). The rate of exchange between 18O-enriched gas, solid single crystal plates and grains of the pure non-doped material was measured. The influence of the particle size and the degree of reduction of the rutile samples upon the diffusion rate was determined. The diffusion coefficient for stoichiometric non-reduced samples was 1·7 x 10-15cm2/s in the direction perpendicular to the c-axis and 3·2 x 10-16cm2/s parallel to it. Following short-term reduction at 1200C, an increase in the diffusion rate was observed. This increase appeared to be independent of the duration of the heating (1 to 10h), but the amount of increase was the same whether the reduction was performed in vacuum or in air. No influence of the particle size upon the diffusion rate was observed, but marked effects were noted for the surface exchange coefficient.Oxygen Diffusion in Single Crystals of Titanium Dioxide. Gruenwald, T.B., Gordon, G.: Journal of Inorganic and Nuclear Chemistry, 1971, 33[4], 1151-5