Oxygen diffusion in rutile crystals was measured at 710 to 1300C by means of gas/solid isotope exchange with 18O-labelled oxygen. It was found that the data could be described by:

D(cm2/s) = 2.0·x 10-3exp[-60(kcal/mol)/RT]

With respect to disorder in the rutile crystal, the results were clear evidence of the presence of oxygen vacancies. No dependence upon oxygen pressures in the range of 760 to 10-3torr was observed, since the concentration of vacancies due to the impurity oxide content (Al2O3) exceeded the concentration of those formed thermally. The O diffusion was greater perpendicular, than parallel, to the c-axis and was decreased by the presence of H2O.

Oxygen Self-Diffusion in Rutile Crystals. Haul, R., Dümbgen, G.: Journal of Physics and Chemistry of Solids, 1965, 26[1], 1-10