Dresden 2026 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 55: Oxide and insulator surfaces: Structure, epitaxy and growth II

O 55.3: Hauptvortrag

Mittwoch, 11. März 2026, 11:00–11:30, HSZ/0204

Cationic Mixing in Ultrathin Oxide Films: How substrate and oxygen conditions control nanoalloying. — •Jacek Goniakowski — Institut des NanoSciences de Paris, CNRS & Sorbonne Université, Paris, France

While alloying is a powerful strategy for tuning material properties, the fundamental physics and chemistry of cation mixing in metal-supported ultrathin oxide films, including those relevant to inverse catalysts, remain poorly understood, and only a few doped or mixed phases have been characterized at the atomic scale. Here, density functional theory, combined with recent surface science experiments, is used to elucidate how oxygen conditions and substrate properties govern the formation of mixed two-dimensional oxide phases through a subtle interplay of structural and electronic effects.

The study shows that, although bulk V-Fe-O mixed oxides are rare, reduced V-Fe-O monolayers on Pt(111) are stable across a wide range of cation compositions. However, oxidation of the film strongly narrows the accessible compositional window. Likewise, substrate passivation (e.g., oxidized Ru(0001)) restricts the range of stable compositions. For somewhat thicker films, exemplified by V-Cr-O bistacks, the presence of crystallographically distinct cation sites further promotes mixing, enabling the stabilization of spinel-like V-Cr phases with no direct bulk counterparts. Our results highlight key effects governing compositionally complex supported ultrathin oxide films and suggest pathways to explore novel mixed phases.

Keywords: ultrathin films; trasition metal oxides; metal/oxide interface; charge transfer; nanoalloys