The equilibration kinetics of high-purity single-crystal TiO2 were monitored using measurements of electrical conductivity at 1073 to 1323K and oxygen activity, p(O2), range of 10-13 to 75kPa. The kinetic data were used to determine the chemical diffusion coefficient (Dchem) within narrow ranges of p(O2). A complex effect of p(O2) upon Dchem was observed which exhibited a maximum at the n-p transition. The effect of the p(O2) upon Dchem was explained in terms of the defect disorder and the related semiconducting properties. The activation energy of Dchem, which also varied with p(O2), exhibited a maximum (143kJ/mol) at p(O2) = about 104Pa.

Electrical Properties and Defect Chemistry of TiO2 Single Crystal. III. Equilibration Kinetics and Chemical Diffusion. Nowotny, M.K., Bak, T., Nowotny, J.: Journal of Physical Chemistry B, 2006, 110[33], 16292-301