Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 14: Clean surfaces: Metals, semiconductors, oxides and insulators I
O 14.5: Vortrag
Montag, 14. März 2011, 16:00–16:15, WIL B122
Electron localization in defective ceria films: An STM and DFT study — Jan Frederik Jerratsch1, Xiang Shao1, •Niklas Nilius1, Hans-Joachim Freund1, Cristina Popa2, M. Veronica Ganduglia-Pirovano2, and Joachim Sauer2 — 1Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin, Germany — 2Humboldt-Universität zu Berlin, Unter den Linden 6, 10099 Berlin, Germany
Scanning tunnelling microscopy and density functional theory have been employed to identify the spatial correlation between an oxygen vacancy and the associated Ce3+ ion pair in a defective CeO2(111) film. The two Ce3+ ions can occupy different cationic shells around the vacancy (1st to 4th neighbour). The resulting variation in the chemical environment leads to a splitting of the filled Ce3+ f-levels, which is detected with STM spectroscopy. The position of the Ce3+ ion pair is also reflected in characteristic defect patterns observed in empty-state STM images, which result from the bright appearance of Ce4+ ions next to the defect while the Ce3+ remain dark. Both findings demonstrate that at least one extra electron localizes in a Ce ion that is not adjacent to the O vacancy.