Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 57: Nanotribology
O 57.2: Vortrag
Mittwoch, 16. März 2011, 16:45–17:00, WIL C307
Frictional duality of metallic nanoparticles: Influence of particle morphology, orientation, and air exposure — •Dirk Dietzel1, Michael Feldmann1, Udo D. Schwarz2, Ivan Stich3, Jan Brndiar3, and Andre Schirmeisen1 — 1Institute of Physics and Center for Nanotechnology, University of Muenster — 2Department of Mech. Engineering, Yale University, New Haven, USA — 3Institute of Physics, Slovak Academy of Sciences,Bratislava
The contact area dependence of the interfacial friction experienced during the translation of Sb nanoparticles deposited on a graphite substrate is studied under different conditions using the tip of an atomic force microscope as manipulation tool. In vacuum a dual behavior of the friction-area curves is found, characterized by the observation that some particles exhibit friction below the detection limit while other similarly sized particles showed constant shear stress. Detailed investigations prove the reproducibility of this effect, revealing that neither the particle's morphology nor their alignment relative to the substrate lattice influence the findings [1]. In contrast, we observe that temporary exposure to ambient air can lead to a drastic increase in the particle's friction. This finding highlights the strong effect of interface contamination, which is also considered the reason for the frictional duality observed in UHV. To further elucidate the contamination mechanisms, simulations by DFT modelling have been performed for different kinds of conceivable contaminants. These simulations help to get a grasp on the degree and nature of the interface contamination affecting the experiments. [1] Dietzel et al. Phys. Rev. B. 82, 035401 (2010)