Correlation of local structure and diffusion pathways in the modulated anisotropic oxide ion conductor CeNbO4.25
Author(s)
Type
Journal Article
Abstract
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 inter-layer “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 intra-layer; however when obstructed, oxygen can readily move to an adjacent layer along y via alternate lower energy barrier pathways.
Date Issued
2016-02-03
Date Acceptance
2016-01-15
Citation
Journal of the American Chemical Society, 2016, 138 (4), pp.1273-1279
ISSN
0002-7863
Publisher
American Chemical Society
Start Page
1273
End Page
1279
Journal / Book Title
Journal of the American Chemical Society
Volume
138
Issue
4
Copyright Statement
This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of the American Chemical Society, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/jacs.5b11373
Sponsor
Kaust
Engineering & Physical Science Research Council (EPSRC)
Identifier
https://pubs.acs.org/doi/10.1021/jacs.5b11373
Grant Number
N/A
EP/M014142/1
Subjects
Science & Technology
Physical Sciences
Chemistry, Multidisciplinary
Chemistry
BOND-VALENCE PARAMETERS
MOLECULAR-DYNAMICS
TRANSPORT-PROPERTIES
CRYSTAL-CHEMISTRY
COMPUTER-PROGRAM
CERIUM NIOBATE
FUEL-CELLS
CENBO4+DELTA
SIMULATION
OXYGEN
General Chemistry
03 Chemical Sciences
Publication Status
Published
Date Publish Online
2016-01-25