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O: Fachverband Oberflächenphysik

O 56: Oxide Surfaces I

O 56.3: Vortrag

Mittwoch, 13. März 2013, 16:30–16:45, H45

Reversible transformation between α-Fe₂O₃ and Fe₃O₄ — •Francesca Genuzio, Alessandro Sala, Thomas Schmidt, and Hans-Joachim Freund — Fritz-Haber-Institut, Abt. CP, 14195 Berlin

The characterization of the properties of iron oxide thin films and their surfaces is a promising research field, considering the variety of applications those materials are interesting for. The peculiarity of this class of oxides is to assume different properties according to their crystal structure, defined both by stoichiometry and preparation. In thin films, in particular, the influence of the substrate on the quality of the supported oxide-surface and on its thermodynamics is still not clear; moreover the phase diagram of these systems can differentiate significantly from that calculated for bulk materials. We present a combined LEEM and LEED study focused on the systematic characterization of the conditions to reversibly transform α-Fe₂O₃ and Fe₃O₄ thin films on Pt(111) and on Ag(111). Experiments were carried out with the SMART spectro-microscope, an aberration-corrected energy-filtered LEEM-PEEM system which allows the observation in real time and in situ of the surface with high acquisition rate. A complete characterization of oxidation and reduction of mixed-phase films, as well as the substrate role in such reactions, is discussed.