Dresden 2014 – scientific programme
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O: Fachverband Oberflächenphysik
O 81: Oxide and Insulator Surfaces III
O 81.6: Talk
Thursday, April 3, 2014, 17:15–17:30, PHY C 213
Ordered Phases of Reduced Ceria as Epitaxial Films on Cu(111) — Tomáš Duchoň, Filip Dvořák, Marie Aulická, Vitalii Stetsovych, Mykhailo Vorokhta, Daniel Mazur, Kateřina Veltruská, Tomáš Skála, •Josef Mysliveček, Iva Matolínová, and Vladimír Matolín — Charles University in Prague, Faculty of Mathematics and Physics, Department of Surface and Plasma Physics, V Holešovičkách 2, 18000 Praha 8, Czech Republic
We study the relationship between the stoichiometry and the structure in thin epitaxial films of reduced ceria, CeOx, 1.5≤x≤2, prepared via an interface reaction between a thin ceria film on Cu(111) and a Ce metal deposit. We show that the transition between the limiting stoichiometries CeO2 and Ce2O3 is realized by equilibration of mobile oxygen vacancies near the surface of the film, while the fluorite lattice of cerium atoms remains unchanged during the process. We identify three surface reconstructions representing distinct oxygen vacancy ordering during the transition, √7×√7R19.1∘, 3×3, and 4×4 corresponding to bulk phases of ceria ι-Ce7O12, CeO1.67, and c-Ce2O3 [1], respectively. Due to the special property to yield ordered phases of reduced ceria the interface reaction between Ce and thin film ceria represents a unique tool for oxygen vacancy engineering. The perspective applications include advanced model catalyst studies with both the concentration and the coordination of oxygen vacancies precisely under control.
[1] Stetsovych, V.; et al., Epitaxial Cubic Ce2O3 Films via Ce-CeO2 Interfacial Reaction. J. Phys. Chem. Lett. 2013, 4, 866-871.