A first-principles theoretical study of the diffusion mechanism of Ti interstitials and O vacancies in rutile was reported. It was found that the diffusion depended strongly upon the defect charge. Weakly charged Ti ions diffuse preferentially through the open channels along the c axis with a barrier of ∼0.4eV. The Ti4+ ions, however, diffused perpendicular to the c-axis via an interstitialcy mechanism with a barrier of ∼0.2eV. Neutral oxygen vacancies diffused along the c axis with a barrier of 0.65eV.

A First Principles Study on Charge Dependent Diffusion of Point Defects in Rutile TiO2. Asaduzzaman, A.M., Krüger, P.: Journal of Physical Chemistry C, 2010, 114[46], 19649-52