Berlin 2015 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 65: Oxides and Insulators

O 65.6: Poster

Mittwoch, 18. März 2015, 18:15–21:00, Poster A

Adsorption of H₂O at Cleaved Sr_n+1Ru_nO_3n+1 and Ca₃Ru₂O₇ (001) Surfaces — •Daniel Halwidl¹, Bernhard Stöger¹, Florian Mittendorfer¹, Wernfried Mayr-Schmölzer¹, Zhiming Wang¹, David Fobes², Jin Peng², Zhiqiang Mao², Michael Schmid¹, Josef Redinger¹, and Ulrike Diebold¹ — ¹Institute of Applied Physics and Center for Computational Materials Science, Vienna University of Technology, Vienna, Austria — ²Department of Physics and Engineering Physics, Tulane University, New Orleans, LA, USA

Complex ternary perovskite oxides are increasingly used in solid oxide fuel cells and catalysis [1]. Therefore it is highly desirable to obtain a better understanding of their surface chemical properties. We use low-temperature scanning tunneling microscopy and DFT to investigate the adsorption of H₂O on Sr_n+1Ru_nO_3n+1 (n=1,2) and Ca₃Ru₂O₇. Dosing water at 105 K on the clean surfaces leads to dissociation of the molecule forming an (OH)_ads group and an O_surfH group. While no long-range diffusion was observed at 78 K on neither Sr_n+1Ru_nO_3n+1 or Ca₃Ru₂O₇, we observe a locally restricted movement of the (OH)_ads around the O_surfH on Sr_n+1Ru_nO_3n+1. Annealing to room temperature leads to diffusion, enabling interactions and the formation of 1D chains. Adsorbed water forms various superstructures with long-range order depending on the coverage, dosing temperature and annealing time. This work was supported by the Austrian Science Fund (FWF project F45) and the ERC Advanced Grant “OxideSurfaces”.

[1] M. A. Pena, and J. L. G. Fierro, Chem. Rev. 101, 1981 (2001).