Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 44: Poster Session II (Semiconductors; Oxides and Insulators: Adsorption, Clean Surfaces, Epitaxy and Growth; Surface Chemical Reactions and Heterogeneous Catalysis; Surface or Interface Magnetism; Solid-Liquid Interfaces; Organic, Polymeric, Biomolecular Films; Particles and Clusters; Methods: Atomic and Electronic Structure; Time-resolved Spectroscopies)
O 44.59: Poster
Mittwoch, 28. März 2007, 17:00–19:30, Poster C
Stability of Fe3O4(001) in a humid environment — •Narasimham Mulakaluri1, Rossitza Pentcheva1, and Matthias Scheffler2 — 1Section Crystallography, Dept. for Earth and Environmental Sciences, University of Munich — 2Fritz-Haber-Institut der MPG, Berlin
The interaction of water with a mineral surface is a fundamental process both in nature and technology. We study the influence of water adsorption on the energetics and properties of the Fe3O4(001) surface using density functional theory (DFT)-calculations with the FP-LAPW method in the WIEN2k implementation. The surface stability of different terminations as a function of the O2 and H2O pressure is compared in the framework of ab initio thermodynamics. On the clean surface a bulk termination containing oxygen and octahedral iron is stabilized through a Jahn-Teller distortion [1]. For this so called modified B-layer as well as the half occupied A-layer termination we vary the degree of hydroxilation of the surface. At water rich conditions where the surface is completely covered by hydroxyl groups a B-layer is found to be favored compared to other models. We investigate also the role of water adsorption on surface reconstruction and find a tendency towards outward relaxation of the surface atoms covered by hydroxyl groups. For the hydroxilated surfaces we obtain metallic behavior compared to the half-metallic bulk, however, the surface states in the majority band gap have a different character compared to the clean surface.
[1] R. Pentcheva et al., Phys. Rev. Lett. 94,126101 (2005).