Factors Governing Oxygen Vacancy Formation in Oxide Perovskites

The control of oxygen vacancy (V-O) formation is critical to advancing multiple metal-oxide-perovskite-based technologies. We report the construction of a compact linear model for the neutral V-O formation energy in ABO(3) perovskites that reproduces, with reasonable fidelity, Hubbard-U-corrected density functional theory calculations based on the state-of-the-art, strongly constrained and appropriately normed exchange-correlation functional. We obtain a mean absolute error of 0.45 eV for perovskites stable at 298 K, an accuracy that holds across a large, electronically diverse set of ABO(3) perovskites. Our model considers perovskites containing alkaline-earth metals (Ca, Sr, and Ba) and lanthanides (La and Ce) on the A-site and 3d transition metals (Ti, V, Cr, Mn, Fe, Co, and Ni) on the B-site in six different crystal systems (cubic, tetragonal, orthorhombic, hexagonal, rhombohedral, and monoclinic) common to perovskites. Physically intuitive metrics easily extracted from existing experimental thermochemical data or via inexpensive quantum mechanical calculations, including crystal bond dissociation energies and (solid phase) reduction potentials, are key components of the model. Beyond validation of the model against known experimental trends in materials used in solid oxide fuel cells, the model yields new candidate perovskites not contained in our training data set, such as (Bi,Y)(Fe,Co)O-3, which we predict may have favorable thermochemical water-splitting properties. The confluence of sufficient accuracy, efficiency, and interpretability afforded by our model not only facilitates high-throughput computational screening for any application that requires the precise control of V-O concentrations but also provides a clear picture of the dominant physics governing V-O formation in metal-oxide perovskites.

Automated summary

The study presents a compact linear model for predicting the energy of neutral oxygen vacancy formation in ABO(3) perovskites, showing reasonable accuracy across a diverse set of perovskites. The model considers perovskites containing alkaline-earth metals and lanthanides on the A-site, and 3d transition metals on the B-site, with physically intuitive metrics extracted from experimental thermochemical data or inexpensive quantum mechanical calculations playing a key role. The model not only validates against known trends but also identifies new candidate perovskites for potential applications like thermochemical water-splitting, showcasing a valuable tool for high-throughput computational screening and understanding the dominant physics of oxygen vacancy formation in metal-oxide perovskites.