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

Lookup NU author(s): Dr Stevin Pramana

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This is the authors' accepted manuscript of an article that has been published in its final definitive form by American Chemical Society, 2016.

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Abstract

© 2016 American Chemical Society. CeNbO4.25 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 CeNbO4.25 forms with a unit cell 12 times larger than the stoichiometric tetragonal parent phase of CeNbO4 as a result of the helical ordering of Ce3+ and Ce4+ ions along z. Interstitial oxygen ion incorporation leads to a cooperative displacement of the surrounding oxygen species, creating interlayer NbO6 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.


Publication metadata

Author(s): Pramana SS, Baikie T, An T, Tucker MG, Wu J, Schreyer MK, Wei F, Bayliss RD, Kloc CL, White TJ, Horsfield AP, Skinner SJ

Publication type: Article

Publication status: Published

Journal: Journal of the American Chemical Society

Year: 2016

Volume: 138

Issue: 4

Pages: 1273-1279

Print publication date: 03/02/2016

Online publication date: 15/01/2016

Acceptance date: 30/10/2015

Date deposited: 02/05/2019

ISSN (print): 0002-7863

ISSN (electronic): 1520-5126

Publisher: American Chemical Society

URL: https://doi.org/10.1021/jacs.5b11373

DOI: 10.1021/jacs.5b11373


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