Temperature-dependent frictional properties of ultra-thin boron nitride nanosheets

We investigate the temperature-dependent frictional properties of mono- and few-layer hexagonal boron nitride nanosheets (BNNSs) by using atomic force microscopy (AFM). The measurements reveal that a modest increase in sample temperature results in a substantial decrease of the frictional force between a silicon AFM tip and a BNNS, and the frictional force change is modulated by the scan velocity of the AFM tip and the number of layers in the BNNS. The activation energy of the contact rupture for the examined BNNSs is found to be around 0.35 eV, which is substantially higher than the reported values for graphene. The observed high activation energy for the BNNS is ascribed to its electronically and topographically corrugated surface, which originates from the polarized nature of B-N bonds and the size difference of B and N atoms. The findings are useful to better understand the physical properties of hexagonal BNNS materials and in the pursuit of their applications, such as substrate materials in nano ele...