摘要
The structure and properties of CeO2 surfaces have been intensively studied due to their importance in a lot of surface-related applications. Since most of surface techniques probe the structure information inside the outermost surface plane, the subsurface structure information has been elusive in many studies. Using the profile imaging with aberration-corrected transmission electron microscopy, the structure information in both the outermost layer and the sublayers of the CeO2（100） surface has been obtained. In addition to the normal structures that have been reported before, where the surface is Ce-or O-terminated, a metastable surface has been discovered. In the new structure, there is an atomic layer reversal between the outermost layer and the sublayer, giving a structure with O as the outermost layer for the stoichiometry of normal Ce-terminated surface. The charge redistribution for the polarity compensation has also been changed relative to the normal surface.
氧化铈表面的结构与性能对氧化铈材料的许多实际应用有着重要的影响,因此受到了广泛的关注和研究.由于大多数的表面技术仅限于获得表面最外层原子的结构信息,对材料亚表面的结构信息还非常匮乏.我们基于像差校正高分辨透射电子显微技术,同时获得了氧化铈(100)表面和亚表面的结构信息,从而揭示了氧化铈(100)表面的一种亚稳态.在这种新结构中,表面最外层和次外层原子面发生了反转,使得具有Ce终结的化学计量比的表面以O原子面暴露在最外层.伴随这种原子面反转,为了补偿表面极性的电荷重排也不同于正常的(100)表面.
基金
supported by the National natural Science Foundation of China(51525102,51390475,51371102 and 21673277)
the National Basic Research Program of China(2015CB654902)
