Recent theoretical work has suggested that gold nanoclusters on graphite can exhibit both diffusional friction and a novel ballistic friction behavior [1]. This ability to tune friction at nanoscale interfaces can be useful for developing nanoscale motors and machines in general. Furthermore, understanding this nanotribological behavior can be utilized for various nanomechanical devices fabricated from graphene, which is chemically identical to graphite.

 

We have measured the frictional energy dissipation of gold nanoclusters on graphene as a function of temperature and cluster size using the quartz crystal microbalance (QCM) ring-down technique. By measuring this dissipation, it is possible to quantitatively measure the island diffusion coefficient and precisely monitor how the diffusion and slip time change with temperature, and directly compare these results with the recent theoretical studies. In addition, our measurements give insight into the nanotribological properties of a two dimensional material studied at higher sliding speeds than typically accessible using atomic force microscopy.

 

[1] R. Guerra et al. Nature Materials 9, 634 (2010).