Beilstein J. Nanotechnol.2018,9, 1995–2014, doi:10.3762/bjnano.9.190
such as contactageing [30][31][32][33] or the dependence of friction on the scan direction over crystalline surfaces [34][35][36][37][38] were explored.
To address many properties over a broad range of experimental conditions it is sufficient to use simple theoretical models that describe
sliding nanostructures. A first indication stems from nanomanipulation experiments performed for Sb nanoparticles on HOPG, where distinct contact-ageing effects were demonstrated. By characterizing the ageing dynamics as a function of the temperature, of the sliding velocity, and of the hold time in
nanoparticle stick–slip experiments [85][86], contactageing was characterized as a thermally activated process [87]. Atomic-scale interface relaxations, either by single-atom displacements or by the formation and growth of commensurate patches at the interface [88], can serve as a likely explanation for the
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Figure 1:
a) Scheme of a MoO3 nanocrystal on MoS2. The AFM tip is firmly positioned on top on the nanocrystal...
Beilstein J. Nanotechnol.2018,9, 1647–1658, doi:10.3762/bjnano.9.157
ultrahigh vacuum. We measured very low friction forces compared to adhesion forces and found a modulation of lateral forces reflecting the atomic structure of the surfaces. Holding the force-microscopy tip stationary for some time did not lead to an increase in static friction, i.e., no contactageing was
observed for these pairs of tip and surface. Passivating layers from tip or surface were removed in order to allow for contactageing through the development of chemical bonds in the static contact. After removal of the passivating layers, tribochemical reactions resulted in strong friction forces and tip
wear. Friction, wear, and the re-passivation by oxides are discussed based on results for the temporal development of friction forces, on images of the scanned area after friction force microscopy experiments, and on electron microscopy of the tips.
Keywords: contactageing; friction; nanotribology
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Figure 1:
Friction force maps for a) an oxidized Si(100) surface scanned with an intact Ar-sputter cleaned SiO...