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O-vacancy and surface on CeO2: A first-principles study
Authors:Siqi Shi  Yuanhao Tang  Lixia Cui  Peijuan Li  Hua Zhang  Liquan Chen
Affiliation:a Department of Physics, Center for Optoelectronics Materials and Devices, Zhejiang Sci-Tech University, Xiasha College Park, Hangzhou 310018, China
b Laboratory for Solid State Ionics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
c Department of Physics, Jiangxi Normal University, Nanchang 330022, China
d School of Materials Science and Engineering, Chonnam National University, Gwangju 500-757, Republic of Korea
Abstract:Atomic and electronic structures of CeO2 (1 1 1), (1 1 0) and (1 0 0) surfaces are investigated using the first-principles density functional theory taking into account the on-site Coulomb interaction. Both the stoichiometric and O-deficient surfaces are examined in order to clarify the overall features. The CeO2 (1 1 1) is found to be the most stable surface, followed by the (1 1 0) and (1 0 0) surfaces, consistent with experimental observations. Three surfaces exhibit different features of relaxation. Large relaxations are found at the (1 1 0) and (1 0 0) surfaces, while very small changes are observed at the (1 1 1) surface. It is found that the O-vacancy occurs more readily at the (1 1 0) surface as compared with the (1 1 1) surface. Furthermore, the formation energies of the O-vacancy in the surfaces are lower than that in the bulk. The energetically favorable O-vacancy locates in the second O-atomic layer for the (1 1 1) while at the surface layer for the (1 1 0). The excess electrons left with the removal of the O atom are distributed in the first two layers with certain (a considerable) fraction filling the Ce-4f states.
Keywords:A. Ceramics   A. Oxides   A. Surfaces   D. Electronic structure   C. Ab initio calculations
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