Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 89: Oxides and Insulator Surfaces II
O 89.3: Vortrag
Donnerstag, 10. März 2016, 15:30–15:45, H4
(100)-oriented CeO2 Nanoislands: Structure and Polarity Compensation — •Niklas Nilius1, Yi Pan2, Hans-Joachim Freund2, Claudine Noguera3, and Jacek Goniakowski3 — 1Carl von Ossietzky Universität Oldenburg, Institut für Physik, D-26111 Oldenburg, Germany — 2FHI-Berlin, Fradayweg 14-16, D-14195 — 3CNRS-Sorbonne Universités, UPMC Univ. Paris 06, UMR 7588, INSP, F-75005 Paris, France
Compact CeO2(111) films grown on Ru(0001) can be transformed into well-shaped nanoparticles by annealing them in an oxygen-poor environment. With increasing temperature, the particles undergo a shape evolution that finally leads to crystallites exposing wide (100) facets. The atomic structure of the (100) termination has been determined with a combination of high-resolution scanning tunneling microscopy and density functional theory. Two surface reconstructions are identified, composed either of CeO4 nano-pyramids in a (2×2) arrangement or oxygen adatoms forming a c(2×2) super-structure. Both terminations enable full compensation of the polar dipole intrinsic to CeO2(100), but also reflect a gradual reduction of the oxide that proceeds from the surface. Our study provides insights into the rarely explored (100) termination of ceria, which represents a good model system for structurally open and polar oxide surfaces.