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Oxygen Vacancy Ordering and the Conductivity Maximum in Y(2)O(3)-Doped CeO(2)

M. Burbano ; Stefan T. Norberg (Institutionen för kemi- och bioteknik, Oorganisk miljökemi) ; S. Hull ; Sten G. Eriksson (Institutionen för kemi- och bioteknik, Oorganisk miljökemi) ; D. Marrocchelli ; P. A. Madden ; G. W. Watson
Chemistry of Materials (0897-4756). Vol. 24 (2012), 1, p. 222-229.
[Artikel, refereegranskad vetenskaplig]

The defect structure and ionic diffusion processes within the anion-deficient, fluorite structured system Ce(1-x)Y(x)O(2-x/2) have been investigated at high temperatures (873 K-1073 K) as a function of dopant concentration, x, using a combination of neutron diffraction studies, impedance spectroscopy measurements, and molecular dynamics (MD) simulations using interionic potentials developed from ab initio calculations. Particular attention is paid to the short-range ion-ion correlations, with no strong evidence that the anion vacancies prefer, at high temperature, to reside in the vicinity of either cationic species. However, the vacancy-vacancy interactions play a more important role, with preferential ordering of vacancy pairs along the < 111 > directions, driven by their strong repulsion at closer distances, becoming dominant at high values of x. This effect explains the presence of a maximum in the ionic conductivity in the intermediate temperature range as a function of increasing x. The wider implications of these conclusions for understanding the structure property relationships within anion-deficient fluorite structured oxides are briefly discussed, with reference to complementary studies of yttria and/or scandia doped zirconia published previously.

Nyckelord: reverse Monte Carlo (RMC), molecular dynamics (MD), oxygen vacancy, ordering, cation interactions, doped ceria (CeO(2)), SOFC electrolytes, solid oxide electrolyte, yttria-doped ceria, fuel-cells, molecular-dynamics, ionic-conductivity, construction, zirconia, energy

Denna post skapades 2012-02-07. Senast ändrad 2012-02-10.
CPL Pubid: 154827


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Institutionen för kemi- och bioteknik, Oorganisk miljökemi (2005-2014)



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