Surface-based manipulation of point defects in rutile TiO₂

Through isotopic self-diffusion measurements, the present work resolves a discrepancy in the literature about the primary oxygen-related point defect in rutile TiO₂ by showing that suitably prepared surfaces can controllably inject large numbers of an exceptionally mobile defect. Results strongly suggest that this defect is the oxygen interstitial, whose existence in TiO₂ has been predicted computationally but never experimentally confirmed. The surface pathway offers an approach for replacing donor oxygen vacancies with acceptor oxygen interstitials facilitating manipulation of near-surface electronic bands.