Correlation of Local Structure and Diffusion Pathways in the Modulated Anisotropic Oxide Ion Conductor CeNbO4.25

Stevin S. Pramana, Tom Baikie, Tao An, Matthew G. Tucker, Ji Wu, Martin K. Schreyer, Fengxia Wei, Ryan D. Bayliss, Christian L. Kloc, Timothy J. White, Andrew P. Horsfield, Stephen J. Skinner

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

CeNbO is reported to exhibit fast oxygen ion diffusion at moderate temperatures, making this the prototype of a new class of ion conductor with applications in a range of energy generation and storage devices. To date, the mechanism by which this ion transport is achieved has remained obscure, in part due to the long-range commensurately modulated structural motif. Here we show that CeNbO forms with a unit cell 12 times larger than the stoichiometric tetragonal parent phase of CeNbO as a result of the helical ordering of Ce and Ce ions along z. Interstitial oxygen ion incorporation leads to a cooperative displacement of the surrounding oxygen species, creating interlayer NbO connectivity by extending the oxygen coordination number to 7 and 8. Molecular dynamic simulations suggest that fast ion migration occurs predominantly within the xz plane. It is concluded that the oxide ion diffuses anisotropically, with the major migration mechanism being intralayer; however, when obstructed, oxygen can readily move to an adjacent layer along y via alternate lower energy barrier pathways.
Original languageEnglish (US)
Pages (from-to)1273-1279
Number of pages7
JournalJournal of the American Chemical Society
Volume138
Issue number4
DOIs
StatePublished - Jan 25 2016
Externally publishedYes

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