A-Site Doping to Alter Oxygen Vacancy Diffusion in SrTiO₃

Doped SrTiO₃ is a promising material for many applications where oxygen vacancy diffusion is either critical to device function or a source of failure. This work provides new insight into long-range oxygen vacancy diffusion in SrTiO₃ doped with Mn²⁺, Cr³⁺, or Fe²⁺ on the A-site. Density functional theory and the nudged elastic band method are used to calculate oxygen vacancy diffusion barriers adjacent to the dopant and at remote sites. Relative to the pure SrTiO₃ structure, doping was found to raise the diffusion barrier for V_O ^•• vacancies and lower the diffusion barrier for V_O vacancies. Furthermore, a doping trapping radius of 6 Å was found for both the V_O and V_O ^•• vacancies. Counterintuitively, trapping was observed even in supercells where vacancies and dopants are both positively charged. These results provide new insight into how less common A-site doping can change the electronic structure of this important material.