Atomic layer reversal on CeO₂ (100) surface

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.