Dresden 2009 – scientific programme
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O: Fachverband Oberflächenphysik
O 53: Nanostructures at surfaces: Dots, particles, clusters III
O 53.6: Talk
Thursday, March 26, 2009, 16:15–16:30, SCH A215
Gas Sensitivity in Nanoporous Crystalline Metal Oxides: Dependence on Coordination Number — •Julia Draeger1, Markus Ulrich1, Claus-Dieter Kohl2, Stefanie Russ3, and Armin Bunde1 — 1Institut für Theoretische Physik III, Justus-Liebig-Universität, Heinrich-Buff-Ring 16, 35392 Giessen — 2Institut für Angewandte Physik, Justus-Liebig-Universität, Heinrich-Buff-Ring 16, 35392 Giessen — 3Institut für Theoretische Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin
We use a percolation model to study numerically and analytically the influence of gas adsorption on the conductance of thin films of nanoporous crystalline metal oxides. We model the layers by a network of intergranular contacts with conductances that depend on the amount of adsorbed gas molecules. For a given layer thickness, average grain size and coordination number we estimate the critical gas concentration Nc below which the nanoporous structure is insulating due to the absence of a percolating cluster of conducting grains. Above Nc, which decreases strongly with the coordination number, the conductance increases rapidly. In order to obtain a low threshold Nc, it is advantegous to consider films consisting of several monolayers with low coordination number.