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O: Fachverband Oberflächenphysik

O 12: Oxides and insulators: Adsorption

O 12.1: Vortrag

Montag, 22. März 2010, 15:00–15:15, H33

Water adsorption on SrTiO₃(001): A density-functional theory study — •Hannes Guhl^1,2, Wolfram Miller¹, and Karsten Reuter^2,3 — ¹Leibniz Institut für Kristallzüchtung Berlin (Germany) — ²Fritz-Haber-Institut Berlin (Germany) — ³TU München (Germany)

SrTiO₃ is a technological oxide, with applications as photo-catalyst, gas-sensor or as substrate for film growth. In many of these applications the surface of SrTiO₃ is deliberately or unintended in contact with water molecules. Aiming for the atomic-scale details of this interaction we perform density-functional theory calculations addressing the adsorption of H₂O on both regular terminations of the SrTiO₃(001) surface. We find that the binding energetics is crucially controlled by long-range surface relaxations. Using this energetics to construct a thermodynamic phasediagram we obtain a different propensity for hydroxylation of the two terminations that is consistent with recent experiments by Iwahori et. al [1]. Around room temperature the SrO-termination becomes hydroxylated already at lowest background humidity, whereas the TiO₂-terminated domains stay practically water-free in the range of low and moderate H₂O vapor pressures.

[1] K. Iwahori et. al J. Appl. Phys. 93, 3227 (2007).