Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 41: Poster Session I (Semiconductor Substrates: Epitaxy and growth; Semiconductor Substrates: Adsorbtion; Semiconductor Substrates: Solid-liquid interfaces; Semiconductor Substrates: Clean surfaces; Oxides and insulators: Epitaxy and growth; Oxides and insulators: Adsorption; Oxides and insulators: Clean surfaces; Organic, polymeric and biomolecular films - also with adsorbates; Organic electronics and photovoltaics, Surface chemical reactions; Heterogeneous catalysis; Phase transitions; Particles and clusters; Surface dynamics; Surface or interface magnetism; Electron and spin dynamics; Spin-Orbit Interaction at Surfaces; Electronic structure; Nanotribology; Solid/liquid interfaces; Graphene; Others)
O 41.18: Poster
Dienstag, 23. März 2010, 18:30–21:00, Poster B1
Characterization of Oxide-based Modelcatalysts- Growth, Morphology and Structure of ultrathin Titaniumoxide- and Ceriumoxide-Films prepared by Oxidation of the Pt-based binary alloys. — •Jan Markus Essen1, Severine Le Moal2, Marco Moors1, Christian Breinlich1, Conrad Becker2, and Klaus Wandelt1 — 1Institute of Physical and Theoretical Chemistry, Wegelerstr. 12, D-53115 Bonn — 2CINaM-CNRS-UPR 3118, Case 913, Marseille Cedex 9, F-13288
Oxidation of bimetallic alloys is a versatile tool for the preparation of ultrathin oxide films. In this study we compare the growth of cerium- and titanium oxide-films obtained by oxidation of PtxCe/Pt(111)- or Pt3Ti(111)-alloys. For both oxides depending on the oxidation temperature, oxygen pressure, or for the PtxCe-alloyphases, the amount of cerium, different structures occur. For cerium oxides only 3 different hexagonal phases are observed, while for the titanium oxides 5, hexagonal and rectangular, phases can be distinguished. This can be interpreted as a result of the interplay between the hexagonal substrate symmetry and the oxide favored symmetry, namely hexagonal for the cerium oxides and rectangular for the titanium oxides. For the cerium oxide a stoichiometric oxidation is possible, while for the titanium oxides, caused by strong realloying, this is not the case. For titanium oxides contrarily to the cerium oxides predominantly a 2D-Growth is observed. This is caused by the good matching of the lattice parameters with the underlying substrate. For cerium oxides a lattice the mismatch leads to cluster-formation and thus to a 3D growth mode.