Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 9: Focus Session: Frontiers in Reducible Oxide Surface Science I

O 9.1: Hauptvortrag

Montag, 12. März 2018, 10:30–11:00, HFT-FT 131

CeO₂(111) defect structure, oxygen migration and polaron hopping: A theoretical perspective — •M. Veronica Ganduglia-Pirovano¹, Gustavo E. Murgida², Valeria Ferrari², Ana Maria Llois², Dawei Zhang³, Zhong-Kang Han^3,4, and Yi Gao^3,4 — ¹ICP-CSIC, Madrid — ²CAC-CNEA, CONICET, Bs. As. — ³SINAP-CAS, Shanghai — ⁴UCAS, Beijing

Deep understanding of the defect structure of ceria(CeO₂) surfaces is essential to tailor their functionality in applications. For the CeO₂(111) surface, whether surface oxygen vacancies attract or repel, and whether oxygen migration and polaron (Ce³⁺) hopping are entangled, are heavily debated. Also, a number of surface reconstructions have been observed upon reduction, but their structures have remained elusive. Here, supported by density-functional theory-based modeling, statistical thermodynamics, Monte Carlo and molecular dynamic simulations, and experimental results, we elucidate: (i) the subsurface preference at low vacancy concentration and temperature [1,2], (ii) the formation of surface vacancy clusters with increased degree of reduction and temperature [2], (iii) the nature of the observed (√7× √7)R19.1^∘, (√7× 3)R19.1^∘, (√3× √3), (3 × 3), and (4 × 4) reconstructions [3], as well as (iv) the role of Ce³⁺ ions in oxygen vacancy migration [4].
[1] G. E. Murgida, M. V. Ganduglia-Pirovano, Phys. Rev. Lett. 110. 246101 (2013).
[2] Z.-K. Han et al., submitted to Phys. Rev. Materials (2017).
[3] R. Olbrich et al. J. Phys. Chem. C, 121, 6844 (2017).
[4] D. Zhang et al. in preparation.