Morphology and nanostructure of CeO2(111) surfaces of single crystals and Si(111) supported ceria films
Autor(en): | Pieper, H. H. Derks, C. Zoellner, M. H. Olbrich, R. Troeger, L. Schroeder, T. Neumann, M. Reichling, M. |
Stichwörter: | CATALYSTS; Chemistry; Chemistry, Physical; DEFECT STRUCTURE; FORCE MICROSCOPY; GROWTH; IONIC-CONDUCTIVITY; OXIDE LAYERS; PHASE-TRANSITION; Physics; Physics, Atomic, Molecular & Chemical; REDOX PROPERTIES; SCANNING-TUNNELING-MICROSCOPY; WATER-GAS SHIFT | Erscheinungsdatum: | 2012 | Herausgeber: | ROYAL SOC CHEMISTRY | Journal: | PHYSICAL CHEMISTRY CHEMICAL PHYSICS | Volumen: | 14 | Ausgabe: | 44 | Startseite: | 15361 | Seitenende: | 15368 | Zusammenfassung: | The surface morphology of CeO2(111) single crystals and silicon supported ceria films is investigated by non-contact atomic force microscopy (NC-AFM) and Kelvin probe force microscopy (KPFM) for various annealing conditions. Annealing bulk samples at 1100 K results in small terraces with rounded ledges and steps with predominantly one O-Ce-O triple layer height while annealing at 1200 K produces well-ordered straight step edges in a hexagonal motif and step bunching. The morphology and topographic details of films are similar, however, films are destroyed upon heating them above 1100 K. KPFM images exhibit uniform terraces on a single crystal surface when the crystal is slowly cooled down, whereas rapid cooling results in a significant inhomogeneity of the surface potential. For films exhibiting large terraces, significant inhomogeneity in the KPFM signal is found even for best possible preparation conditions. Applying X-ray photoelectron spectroscopy (XPS), we find a significant contamination of the bulk ceria sample with fluorine while a possible fluorine contamination of the ceria film is below the XPS detection threshold. Time-of-flight secondary ion mass spectroscopy (TOF-SIMS) reveals an accumulation of fluorine within the first 5 nm below the surface of the bulk sample and a small concentration throughout the crystal. |
ISSN: | 14639076 | DOI: | 10.1039/c2cp42733h |
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