Lattice geometry and stability of low-friction sliding of nanocrystals

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Abstract

Sliding of nanocrystals with incommensurate contact to the substrate leads
to low friction and therefore incommensurate states are interesting for the study
of nanotribology. We study the rotational dynamics and the stability of incom-
mensurate sliding of nanocrystals on crystalline subtrates. By means of a simple,
analytically soluble model, we show that stable incommensurate orientations
exist for different types of substrates and nanocrystals. We analytically and
numerically investigate the low-friction states and their robustnuss for hexago-
nal[1] and square lattices[2]. We compare the results to numerical simulations
of W clusters on NaF(001) and graphite flakes on graphite. We show that the
geometry and high typical corrugation of substrates with square lattices increase
the robustness of the low-friction states compared to typical hexagonal lattices,
such as graphite, where it is difficult to find low-friction states in experiments
which remain stable for long time[1,3].

Key References

[1] Astrid S. de Wijn, C. Fusco, and Annalisa Fasolino, Stability of superlu-
bric sliding on graphite, Physical Review E 81, 046105 (2010).
[2] Astrid S. de Wijn and Annalisa Fasolino, Stability of low-friction surface
sliding of nanocrystal with rectangular symmetry and application to W on
NaF(001), Tribology Letters (2010), in press.
[3] A. E. Filippov, M. Dienwiebel, J. W. M. Frenken, J. Klafter, M. Urbakh:
Torque and twist against superlubricity. Phys. Rev. Lett. 100, 046102 (2008).

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