Understanding Oxygen-Vacancy Migration in the Fluorite Oxide CeO2: An Ab Initio Study of Impurity-Anion Migration

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• 作者：Annalena R. Genreith-Schriever ; Pascal Hebbeker ; Judith Hinterberg ; Tobias Zacherle ; Roger A. De Souza
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：December 24, 2015
• 年：2015
• 卷：119
• 期：51
• 页码：28269-28275
• 全文大小：353K
• ISSN：1932-7455

文摘

The site exchange of an anion moiety (O, N, F, Ne, P, S, Cl, and Ar) with an oxygen vacancy in fluorite-structured CeO₂ was studied by means of density functional theory (DFT) calculations. The obtained activation energies of migration vary between 0.2 and 0.9 eV, and increase with the formal valence of the migrating ion; the size of the migrating ion appears to play a minor role. An analysis of ion displacements suggests that repulsive Coulombic interactions between the migrating anion and oxygen ions as the next-nearest neighbors in the saddle-point configuration provide the dominant contribution to the activation energy of migration. As well as emphasizing the ease with which anion moieties are mobile in AO₂ fluorite materials, these results suggest a new paradigm for understanding fast oxygen-ion conducting materials.