Point-Defect Segregation and Space-Charge Potentials at the Σ5(310)[001] Grain Boundary in Ceria
Author(s)
Usler, Adrian L.; Heelweg, Henrik J.; De Souza, Roger A.; Genreith-Schriever, Annalena R.
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The atomistic structure and point-defect thermodynamics of the model Σ5(310)[001]
grain boundary in CeO2 were explored with atomistic simulations. An interface with a double-diamond-shaped structural repeat unit was found to have the lowest energy. Segregation energies were calculated for oxygen vacancies, electron polarons, gadolinium and scandium acceptor cations, and tantalum donor cations. These energies deviate strongly from their bulk values over the same length scale, thus indicating a structural grain-boundary width of approximately 1.5 nm. However, an analysis revealed no unambiguous correlation between segregation energies and local structural descriptors, such as interatomic distance or coordination number. From the segregation energies, the grain-boundary space-charge potential in Gouy–Chapman and restricted-equilibrium regimes was calculated as a function of temperature for dilute solutions of (i) oxygen vacancies and acceptor cations and (ii) electron polarons and donor cations. For the latter, the space-charge potential is predicted to change from negative to positive in the restricted-equilibrium regime. For the former, the calculation of the space-charge potential from atomistic segregation energies is shown to require the inclusion of the segregation energies for acceptor cations. Nevertheless, the space-charge potential in the restricted-equilibrium regime can be described well with an empirical model employing a single effective oxygen-vacancy segregation energy.
Date issued
2024-08-03Department
Massachusetts Institute of Technology. Department of ChemistryJournal
solids
Publisher
Multidisciplinary Digital Publishing Institute
Citation
Usler, A.L.; Heelweg, H.J.; De Souza, R.A.; Genreith-Schriever, A.R. Point-Defect Segregation and Space-Charge Potentials at the Σ5(310)[001] Grain Boundary in Ceria. Solids 2024, 5, 404-421.
Version: Final published version