Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 49: Oxide and Insulator Surfaces: Adsorption

O 49.5: Poster

Dienstag, 21. März 2017, 18:30–20:30, P1A

DFT study of charged O₂⁻ adsorbed on Ca₃Ru₂O₇(001) — Wernfried Mayr-Schmölzer, Florian Mittendorfer, and •Josef Redinger — Institute of Applied Physics, TU Vienna, Wiedner Hauptstrasse 8-10/134, 1040 Vienna, Austria

An atomic scale knowledge of the surface chemistry of perovskite oxides is surprisingly poor, despite their use in a wide range of important applications, like in sensors, or fuel cells, or even in catalytic processes. Here we present a DFT study of O₂ adsorption on the (001) surface of Ruddelsden-Popper type Ca₃Ru₂O₇. Experimentally Ca₃Ru₂O₇ cleaves nicely, yielding an almost ideally flat rocksalt-like CaO(001) surface. However, due to the tilting and rotation of the RuO₆ octahedra in the bulk different Ca-O distances are present, creating preferred adsorption sites for an O₂ molecule. Upon adsorption O₂ does not dissociate, but rather gets negatively charged. This charging is predicted both for the metallic and the insulating anti-ferromagnetically ordered substrate state, which exists below T_N < 50K. We investigate the origin of the charge transfer using standard PBE, PBE+U and hybrid-functionals and find distinct differences concerning the local magnetic configuration for metallic and insulating states.