The formation energies for the point defect species Ti4+ interstitials, Tii4+, and oxygen vacancies with an effective charge of +2e, Vo2+, were calculated using the polarisable point ion shell model. The formation energy of Tii4+ was found to be a 10.8eV for occupation of the (0½½) site. The energy of Tii4+ at other sites was somewhat higher than this figure, and allowed the migration energy of Tii4+ parallel to the c axis to be estimated as 2.9eV. The formation energy of Vo2+ was found to be 10.1eV. The variation of these formation energies with dielectric constant was also calculated. It was found that the energy of formation of Tii4+ varied considerably with dielectric constant, while the formation energy of Vo2+ was almost independent of dielectric constant. The relevance of these results to the presence of crystallographic shear planes in reduced rutile was considered.

Formation Energies of Point Defects in Rutile (TiO2). Sawatari, H., Iguchi, E., Tilley, R.J.D.: Journal of Physics and Chemistry of Solids, 1982, 43[12], 1147-55