Epitaxial iron oxide growth on a stepped Pt(9 11 11) surface

In an attempt to introduce steps in oxide surfaces in a controlled way, different iron oxide phases were grown on an atomically stepped Pt(9 11 11) surface. For low coverages, wetting FeO(111) films are formed which induce step bunching with doubled and tripled terrace widths. Further Fe deposition and oxidation results in formation of $Fe3O4(111)$ islands in a similar Stranski–Krastanov growth mode as on the basal Pt(111) surface. However, restricted diffusion across the step bunches results in a high concentration of comparatively flat elongated $Fe3O4$ islands which form a closed coalesced film at relatively low overall deposition. High pressure oxidation of coalesced $Fe3O4$ films results in poorly defined $Fe2O3(0001)$⁠. The FeO films grown on vicinal Pt substrates may serve as model systems for systematic studies of well-defined defective oxide surfaces, but the catalytically more relevant $Fe3O4$ and $Fe2O3$ phases cannot be obtained reproducibly with a well-defined step structure.