The formation and migration of charged oxygen vacancies at a ${90}^{\circ }\left(100\right)\left[001\right]$ domain wall in orthorhombic ${\mathrm{CaTiO}}_3$ were studied by means of atomistic simulation techniques. The segregation-energy profiles of an oxygen vacancy across the wall were revealed through careful discrimination to display hyperbolic secant forms, with a domain-wall width consistent with that obtained from a tilt-angle analysis. Equilibrium distributions of oxygen vacancies across the ferroelastic domain wall in a nominally undoped (weakly acceptor-doped) sample were calculated self-consistently (assuming a sech segregation-energy profile) for various temperatures. The calculations indicate a positively charged domain wall, arising from high vacancy concentrations, compensated by negative space-charge layers, in which vacancies are depleted. The activation barriers for oxygen-vacancy migration along the domain wall, determined from nudged-elastic-band calculations, revealed that the long-range diffusion of oxygen vacancies along the wall is neither strongly enhanced nor strongly hindered.

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• Domain walls
• Ionic transport
• Perovskites
• Materials modeling