Regensburg 2010 – scientific programme
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O: Fachverband Oberflächenphysik
O 12: Oxides and insulators: Adsorption
O 12.1: Talk
Monday, March 22, 2010, 15:00–15:15, H33
Water adsorption on SrTiO3(001): A density-functional theory study — •Hannes Guhl1,2, Wolfram Miller1, and Karsten Reuter2,3 — 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).