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PGI-1 Talk: Dr. Annalena Genreith-Schriever

Simulation Studies of Oxygen-Ion Transport in Ceria

16 Aug 2017 11:00
PGI Lecture Hall

Institut für Physikalische Chemie, RWTH Aachen University


Oxygen-ion transport in fluorite-type oxides was studied for the model system ceria CeO2 with computational means. The site exchange of an anion moiety (O, N, F, Ne, P, S, Cl, and Ar) with an oxygen vacancy was investigated with Density Functional Theory (DFT) calculations. The results suggest a new paradigm for understanding fast oxygen-ion conducting materials. The response of mobile oxygen ions to an external electric field was examined with classical Molecular Dynamics (MD) simulations. The standard (quantitative) Mott-Gurney treatment underestimates the migration barriers at high field strengths and consequently overestimates the mobility. A new analytical expression was consequently derived. DFT calculations were used to determine the structure, excess grain-boundary properties and point-defect energetics for the Σ5(310)[001] grain boundary. A method to determine the grain-boundary width was proposed. Space-charge potentials were calculated with continuum models and the influence of an inhomogeneous boundary core was assessed.


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