Berlin 2005 – wissenschaftliches Programm
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O: Oberflächenphysik
O 6: Grenzfl
äche fest-flüssig
O 6.1: Vortrag
Freitag, 4. März 2005, 10:45–11:00, TU EB407
Surface Stress − Charge Coefficient for Charged Nanoporous Platinum — •Viswanath Raghavan Nadar1, Dominik Kramer1, and Jörg Weissmüller1,2 — 1Forschungszentrum Karlsruhe, Institut für Nanotechnologie, Karlsruhe — 2Universität des Saarlandes, Fachrichtung Technische Physik, Saarbrücken
If porous, nanostructured metals immersed in an electrolyte are charged electrically, volumetric expansion and contraction is induced in phase with the applied potential[1,2], with strain amplitudes comparable to those of commercial piezoceramics. Several microscopic interactions contribute to the potential dependence of the surface stress and the corresponding interfacial properties: electrostatic repulsion in the space−charge layers, changes in the bonding between metal atoms, and forces between neighboring adsorbate atoms or between adsorbates and the metal. The relative contributions of these interactions are so far not well understood. The present study is to obtain insight into this issue by studying the electrolyte concentration dependence of the surface stress − charge coefficient ζ for platinum. We compute ζ from the volumetric strain measured from in−situ dilatometer experiments and discuss the influence of specific adsorption. [1] J. Weissmüller et al, Science 300 (2003) 312; [2] D. Kramer, R. N. Viswanath, J. Weissmüller, Nano Letters 4 (2004) 793