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O: Fachverband Oberflächenphysik

O 20: Oxides II: Structures, Interactions and Reducibility

O 20.7: Vortrag

Montag, 16. März 2020, 17:15–17:30, WIL B321

Copper Oxidation on Pt(111) - More than a Surface Oxide? — •Alexander Gloystein and Niklas Nilius — Institute of Physics, Carl von Ossietzky University Oldenburg, Germany

LEED, STM and XPS have been used to monitor the growth of copper oxide thin films on a Pt(111) support. At 500 K preparation temperature, a monolayer oxide forms while most of the precipitated copper accumulates as Cu(111) at the Pt interface. Respective films are composed of distorted Cu-O six-rings and resemble the well-known '29' and '44' surface oxides formed via low-pressure oxidation of Cu(111). With increasing temperature, unreacted Cu mixes with the Pt top-layers, resulting in a well-ordered Cu3Pt surface alloy. In response to this substrate modification, the oxide film undergoes an order-disorder transition, in which an increasing number of 5-7 defects are inserted into the Cu-O honeycomb lattice, before it decays into isolated oxide islands. Above 750 K annealing, uniform Cu3O shamrock units that self-assemble into highly crystalline 2sqrt3 domains become the dominant structural element of the film.