The atomic and electronic structure of oxygen polyvacancies in anatase

We investigate oxygen-deficient anatase using quantum-chemical simulation within the density functional theory and X-ray photoelectron spectroscopy. It is demonstrated that etching of anatase with argon ions with an energy of 2.4 keV results in the formation of oxygen vacancies and polyvacancies at a concentration of approximately 10$^{20}$ cm$^{-3}$ in the crystal. It was found that the most energetically favorable spatial configuration of an oxygen polyvacancy is a three-dimensional chain in crystallographic direction [100] or [010]. The ability of oxygen polyvacancy in the form of a chain to act as a conductive filament and to participate in the resistive switching is discussed.