This study investigates grain growth in the perovskite oxide strontium titanate in an electric field. The seeded polycrystal technique was chosen as it provides a sensitive and controlled setup to evaluate the impact of different parameters on grain growth due to the well‐defined driving force for grain growth. Current blocking electrodes were used to prevent Joule heating. The results show faster grain growth, and thus, higher grain‐boundary mobility at the negative electrode. It is argued that the electric field causes point‐defect redistribution, resulting in a higher oxygen vacancy concentration at the negative electrode. The local oxygen vacancy concentration is suggested to affect the space‐charge potential at the grain boundaries. A thermodynamic treatment of the grain‐boundary potential at a grain boundary without field shows that for a high oxygen vacancy concentration less space‐charge and less accumulation of cationic defects to the boundary occurs. Therefore, at the negative electrode, a higher oxygen vacancy concentration results in less space‐charge and less accumulation of cationic defects. The lower degree of defect accumulation requires less diffusion of segregated defects during grain‐boundary migration, so that at the negative electrode faster grain growth is expected, as found in the experiments.

Weakly acceptor‐doped ceria ceramics were characterized structurally and compositionally with advanced transmission electron microscopy (TEM) techniques and electrically with electrochemical impedance spectroscopy (EIS). The grain boundaries studied with TEM were found to be free of second phases. The impedance spectra, acquired in the range 703 ≤ T/K ≤ 893 in air, showed several arcs that were analyzed in terms of bulk, grain‐boundary, and electrode responses. We ascribed the grain‐boundary resistance to the presence of space‐charge layers. Continuum‐level simulations were used to calculate charge‐carrier distributions (of acceptor cations, oxygen vacancies, and electrons) in these space‐charge layers. The acceptor cations were assumed to be mobile at high (sintering) temperatures but immobile at the temperatures of the EIS measurements. Space‐charge formation was assumed to be driven by the segregation of oxygen vacancies to the grain‐boundary core. Comparisons of data from the simulations and from the EIS measurements yielded space‐charge potentials and the segregation energy of vacancies to the grain‐boundary core. The space‐charge potentials from the simulations are compared with values obtained by applying the standard, analytical (Mott–Schottky and Gouy–Chapman) expressions. The importance of modelling space‐charge layers from the thermodynamic level is demonstrated.

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Many ABX3 perovskite compounds adopt at temperatures of interest a low-symmetry structure, rather than the ideal (cubic) structure. The prototypical case is the mineral perovskite (CaTiO3), which exhibits orthorhombic symmetry...