Berlin 2008 – scientific programme
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O: Fachverband Oberflächenphysik
O 55: Poster Session III - MA 141/144 (Methods: Atomic and Electronic Structure; Particles and Clusters; Heterogeneous Catalysis; Semiconductor Substrates: Epitaxy and Growth+Adsorption+Clean Surfaces+Solid-Liquid Interfaces; Oxides and Insulators: Solid-Liquid Interfaces+Epitaxy and Growth; Phase Transitions; Metal Substrates: Adsorption of Inorganic Molecules+Epitaxy and Growth; Surface Chemical Reactions; Bimetallic Nanosystems: Tuning Physical and Chemical Properties; Oxides and insulators: Adsorption; Organic, polymeric, biomolecular films; etc.)
O 55.12: Poster
Wednesday, February 27, 2008, 18:30–19:30, Poster F
Crystal structure of transition metal oxide nano particles synthesized form ferritin — •Michael Krispin, Florian Sedlmeir, Aladin Ullrich, and Siegfried Horn — Lehrstuhl für Experimentalphysik II, Universität Augsburg, D-86135 Augsburg
We have investigated the local crystal structure of nanosized transition metal oxides by extended x-ray absorption fine structure (EXAFS). Iron and cobalt oxide nanoparticles of different diameters were produced by thermal treatment of horse spleen ferritin molecules and remineralized apo-ferritin molecules, respectively. The structure of these particles was compared to various iron oxide and ferrihydrite references as well as cobalt oxide references. The Fourier transformed (FT) EXAFS spectra of the iron oxide nanoparticles differ significantly from hematite and maghemite reference spectra and change systematically as a function of particle diameter, signalling a corresponding evolution of the structure. A possible explanation therefore is the mixture of hematite and magehmite phases in a core-shell model, in which the fraction of a γ-Fe2O3 like particle shell increases while the hematite core decreases with decreasing particle size. In the case of cobalt oxide nanoparticles we find good agreement of the FT EXAFS spectra to the Co3O4 reference.