Vacancies and Vacancy-Mediated Self Diffusion in Cr2O3: A First-Principles Study

Abstract

Charged and neutral vacancies and vacancy-mediated self-diffusion in α-Cr2O3 were investigated using first-principles density functional theory (DFT) and periodic supercell formalism. The vacancy formation energies of charged defects were calculated using the electrostatic finite-size corrections to account for electrostatic interactions between supercells and the corrections for the bandgap underestimation in DFT. Calculations predict that neutral oxygen (O) vacancies are predominant in chromium (Cr)-rich conditions and Cr vacancies with −2 charge state are the dominant defects in O-rich conditions. The charge-transition levels of both O and Cr vacancies are deep within the bandgap, indicating the stability of these defects. Transport calculations indicate that vacancy-mediated diffusion along the basal plane has lower energy barriers for both O and Cr ions. The most favorable vacancy-mediated self-diffusion processes corresponds to the diffusion of Cr ion in Cr3+ charge state and O ion in O2– state, res...