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| Steric Effects on the Enhanced Oxygen Storage Capacity of Ni Point Defects in Ceria: A First-principles DFT+U Study |
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Abstract: First-principles density functional theory calculations with the inclusion of on-site Coulomb interaction for the Ce4f and Ni3d electrons (DFT+U) are used to study the effects on the atomistic structures induced by the doping of bulk ceria (CeO2) with Ni atoms at substitutional (S) and interstitial (I) lattice sites. It has been found that for Ce0.97Ni0.03O2-S system, the local structure around dopant possesses octahedral symmetry and expands after the formation of oxygen vacancy; while for Ce0.97Ni0.03O2-I system, the local structure around dopant possesses tetrahedral symmetry and shrinks after the formation of oxygen vacancy. Furthermore, based on the analysis of global displacement, it has been found that the atomic relaxation has been accomplished before the formation of oxygen vacancy for Ce0.97Ni0.03O2-S system, which indicates the possibility of simultaneous formation of the oxygen vacancies around substitutional dopant sites.
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Received: 19 December 2010
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2011, Vol. 29 
