Factors Governing Oxygen Vacancy Formation in Oxide Perovskites

The
control of oxygen vacancy (VO) formation is critical
to advancing multiple metal-oxide-perovskite-based technologies. We
report the construction of a compact linear model for the neutral
VO formation energy in ABO3 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 ABO3 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)­O3, 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 VO concentrations but also provides a clear picture of the dominant
physics governing VO formation in metal-oxide perovskites.