Doping of ceria surfaces with lanthanum: a DFT plus U study

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2010-02-25
Authors
Yeriskin, Irene
Nolan, Michael
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IOP Publishing
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Abstract
In this paper we use density functional theory corrected for on-site Coulomb interactions (DFT + U) to study the defects formed in the ceria (111) and (110) surfaces doped with La. To describe consistently the defect formed with substitutional La(3+) doping at a Ce(4+) site we use DFT and DFT + U, with U = 5 eV for Ce 4f states and U = 7 eV for O 2p states. When La(3+) substitutes on a Ce(3+) site, an La(Ce)' + O(O)(center dot) defect state, with an oxygen hole, is formed at both surfaces, but only with the DFT + U approach. The formation energy of an oxygen vacancy in a structure with two La dopants in their most stable distribution is reduced over the undoped surfaces but remains positive. Formation of an oxygen vacancy results in the appearance of a reduced Ce(3+) cation and a compensated oxygen hole, instead of compensation of both oxygen holes, which is typical of metal oxides doped with lower valence cations. We tentatively suggest that the key role in the formation of this unusual defect is played by cerium and arises from the ease with which cerium can be reduced, as compared to other metal oxides. Experimental confirmation of these results is suggested.
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Density functional theory , Augmented-wave method , Low-index surfaces , Electronic structure , Stabilized zirconia , Catalytic activity , Storage capacity , Co adsorption , CeO2 , Oxides , Cerium , Cerium compounds , Defects , Doping (additives) , Lanthanum , Oxygen , Positive ions , Probability density function , Oxygen vacancies
Citation
Yeriskin, I. and Nolan, M. (2010) 'Doping of ceria surfaces with lanthanum: a DFT + U study', Journal of Physics: Condensed Matter, 22(13), 135004 (8pp). doi: 10.1088/0953-8984/22/13/135004
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© 2010 IOP Publishing Ltd. This is an author-created, un-copyedited version of an article accepted for publication in Journal of Physics: Condensed Matter. The publisher is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at http://stacks.iop.org/0953-8984/22/i=13/a=135004