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 A (3+3)-Dimensional \"Hypercubic\" Oxide-Ionic Conductor: Type II Bi2O3-Nb2O5
Please use this identifier to cite or link to this item http://hdl.handle.net/10773/19568

title: A (3+3)-Dimensional \"Hypercubic\" Oxide-Ionic Conductor: Type II Bi2O3-Nb2O5
authors: Ling, Chris D.
Schmid, Siegbert
Blanchard, Peter E. R.
Petricek, Vaclav
McIntyre, Garry J.
Sharma, Neeraj
Maljuk, Andrey
Yaremchenko, Aleksey A.
Kharton, Vladislav V.
Gutmann, Matthias
Withers, Ray L.
keywords: 3-DIMENSIONAL INCOMMENSURATE MODULATION
NEUTRON POWDER DIFFRACTION
SOLID-SOLUTION
FUEL-CELLS
STRUCTURAL-PROPERTIES
BISMUTH SESQUIOXIDE
SUPERSPACE GROUPS
NODAL SURFACES
SYSTEM
PHASE
issue date: 2013
publisher: AMER CHEMICAL SOC
abstract: The high-temperature cubic form of bismuth oxide, delta-Bi2O3, is the best intermediate-temperature oxide-ionic conductor known. The most elegant way of stabilizing delta-Bi2O3 to room temperature, while preserving a large part of its conductivity, is by doping with higher valent transition metals to create wide solid-solutions fields with exceedingly rare and complex (3 + 3)-dimensional incommensurately modulated \"hypercubic\" structures. These materials remain poorly understood because no such structure has ever been quantitatively solved and refined, due to both the complexity of the problem and a lack of adequate experimental data. We have addressed this by growing a large (centimeter scale) crystal using a novel refluxing floating-zone method, collecting high-quality single-crystal neutron diffraction data, and treating its structure together with X-ray diffraction data within the superspace symmetry formalism. The structure can be understood as an \"inflated\" pyrochlore, in which corner-connected NbO6 octahedral chains move smoothly apart to accommodate the solid solution. While some oxide vacancies are ordered into these chains, the rest are distributed throughout a continuous three-dimensional network of wide delta-Bi2O3-like channels, explaining the high oxide-ionic conductivity compared to commensurately modulated phases in the same pseudobinary system.
URI: http://hdl.handle.net/10773/19568
ISSN: 0002-7863
publisher version/DOI: http://doi.org/10.1021/ja3109328
source: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
appears in collectionsCICECO - Artigos

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