Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 27: Metal Oxide Surfaces I: Structure, Epitaxy and Growth

O 27.9: Vortrag

Dienstag, 2. April 2019, 12:45–13:00, H16

Iron cation diffusion in the near-surface region of Fe₃O₄ (001) — •Steffen Tober^1,2, Marcus Creutzburg^1,2, Björn Arndt^1,2, Konstantin Krausert^1,2, Stefan Mattauch³, Sabine Pütter³, Amir S. Mohd³, Alexandros Koutsioubas³, Lukas Volgger⁴, Herbert Hutter⁴, Heshmat Noei¹, Vedran Vonk¹, Dieter Lott⁵, and Andreas Stierle^1,2 — ¹Deutsches Elektronensynchrotron Hamburg — ²Universität Hamburg, Fachbereich Physik — ³Jülich Centre for Neutron Science — ⁴Technische Universität Wien, CTA — ⁵Helmholtz Zentrum Geesthacht

Magnetite is a versatile catalyst, used for example in the water-gas-shift-reaction or the Fischer-Tropsch synthesis. Its excellent catalytic properties are closely linked to the defect structure in the near surface region. Scanning tunnelling microscopy (STM) and low energy electron diffraction (LEED) studies of the (√2 × √2)R45 ^∘ reconstructed (001) surface suggested a subsurface cation vacancy stabilisation mechanism, also confirmed by surface x-ray diffraction (SXRD) [1,2].

We present the results for the homoepitaxial growth of ⁵⁷Fe₃O₄ on magnetite (001) substrates by reactive molecular beam epitaxy (MBE). Using ⁵⁷Fe as a marker, the interdiffusion of iron ions across the film-substrate interface was followed by combining neutron reflectometry [3] and time of flight secondary ion mass spectroscopy (TOF-SIMS).

[1] Bliem, R. et al. Science. 346, 1215 (2014)

[2] Arndt, B. et al. Surf. Sci. 653, 76 (2016)

[3] Schmidt et al., Adv. Eng. Mat. 11, 446 (2009)