Regensburg 2016 – scientific programme
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O: Fachverband Oberflächenphysik
O 25: Oxide and Insulator Surfaces: Structure and Growth
O 25.2: Poster
Monday, March 7, 2016, 18:15–20:30, Poster E
Oxygen-induced phase switch of sub-monolayer iron oxide on Ir(100) — •Christopher Sobel, Pascal Ferstl, Lutz Hammer, and M.Alexander Schneider — Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstr. 7, 91058 Erlangen
By means of STM and LEED we show that two different sub-monolayer iron oxide phases exist on the Ir(100) surface which can be converted into each other by changing the chemical potential of oxygen. In oxygen poor conditions a 3×1-phase of one-dimensional FeO2 wires forms which covers the whole surface homogeneously. In contrast oxygen rich conditions lead to a condensation into compact islands of quasi-hexagonal FeO(111) with an incommensurate "c(8.8×2)"-structure. The remaining iridium surface is covered by a pure oxygen 2×1-O phase [1]. The energy gain when forming the latter appears to be the driving force for the switch between the extended 3×1 and the compact island iron oxide phase. The behaviour differs qualitatively from other transition metals as for example cobalt, where in oxygen rich conditions the wires change from CoO2 to CoO3 stoichiometry. This fact indicates a delicate energy balance between the different phases.
[1] K. Johnson et al., J. Chem. Phys. 112, 10460 (2000)