Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 57: Solid / liquid interfaces II
O 57.6: Vortrag
Mittwoch, 28. März 2012, 18:00–18:15, A 060
Dynamic Electro-Chemo-Mechanical Analysis — •Qibo Deng1, Maxim Smetanin1, and Jörg Weissmüller1,2 — 1Institut für Werkstoffphysik und -Technologie, Technische Universität Hamburg-Harburg, Hamburg — 2Institut für Werkstoffforschung, Werkstoffmechanik, Helmholtz-Zentrum Geesthacht, Geesthacht
In various instances in surface science it is of relevance to study coupling between mechanical stress or strain of surface and its thermodynamic or electrochemical properties. Experiments use alternatively cantilever bending measurements of the variation of surface stress f, with charge density q, during electrochemical cycles or Dynamic Electro-Chemo-Mechanical Analysis(DECMA), which detects the coupling between electrode potential E, and strain e. At equilibrium, a Maxwell relation equates relevant response parameters,ζE=ζf where ζf=df/dq|e and ζE=dE/de|q. The surfaces under study are not perfect single crystals. They contain defects such as step edges and terraces. Indeed ζE or ζf vary significantly between as-prepared and annealed states of electrode. A recent analysis of surface stress measurements on rough electrode surfaces finds corrugation has an important effect on the way in which f is transferred into the substrate. The action of f can even invert its sign; this appears at moderate values of roughness. We adopt theory to correct DECMA data. Our analysis shows the variation of ζE between different states of surface is indeed controlled by mechanics and can be precisely corrected. The finding has implications for reported values of ζ and for the design of commercial cantilever arrays exploiting surface stress changes for sensing.