| Autor: |
H. Nörenberg, John H. Harding |
| Rok vydání: |
2001 |
| Předmět: |
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| Zdroj: |
Surface Science. 477:17-24 |
| ISSN: |
0039-6028 |
| Popis: |
We have studied the atomic structure of the CeO 2 (0 0 1) surface as an example for a polar “type III” surface by scanning tunnelling microscope (STM), low energy electron diffraction (LEED) and atomistic simulation. High resolution STM on single crystalline CeO 2 (0 0 1) revealed a 2 2 (3×2)R45° surface reconstruction. Calculation confirmed oxygen in the top layer. Upon removal of further oxygen, Ce 4+ ions in the subsurface layer are reduced to Ce 3+ . Because oxygen from bridging positions is removed during this process the surface maintains its 2 2 (3×2)R45° reconstruction. Atomistic modelling showed that an arrangement of Ce 3+ ions in lines is energetically favourable compared to other structures. Among a number of surfaces considered the 2 2 (3×2)R45° reconstruction was energetically most favoured. These results confirm the experimental findings and show that polar “type III” surfaces in metal oxides reduce their surface energy by reconstruction. After reoxidation and annealing a c(3×3) surface reconstruction was found. LEED investigations confirmed the STM results and indicate some disorder of the surface in the [1 1 0] direction. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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