Frictional characteristics of atomically thin sheets.

Title	Frictional characteristics of atomically thin sheets.
Authors	Changgu Lee, Qunyang Li, William Kalb, Xin-Zhou Liu, Helmuth Berger, Robert W Carpick, James Hone
Magazine	Science (New York, N.Y.)
Date	04/02/2010
DOI	10.1126/science.1184167
Introduction	In this study, we utilised friction force microscopy to assess the nanoscale frictional properties of atomically thin sheets of graphene, molybdenum disulphide (MoS2), niobium diselenide, and hexagonal boron nitride on a silicon oxide substrate. We observed that friction increases as the number of layers decreases, a trend consistent across all materials. While suspended graphene membranes followed the same pattern, adherence to a mica surface reduced this effect. The adhesive forces between tip and sample remained constant regardless of thickness or substrate. Graphene and MoS2 displayed atomic lattice stick-slip friction, with the thinnest sheets showing increased static friction related to sliding length. These findings, supported by finite element modelling, suggest that thinner sheets' increased potential for out-of-plane elastic deformation contributes to this trend, which may be intrinsic to atomically thin materials weakly adhered to substrates.
Quote	Changgu Lee, Qunyang Li and William Kalb et al. Frictional characteristics of atomically thin sheets.. Science (New York, N.Y.). 2010. Vol. 328(5974). DOI: 10.1126/science.1184167
Element	Carbon (C) , Molybdenum (Mo) , Niobium (Nb) , Boron (B)
Materials	Nanocomposites , Semiconductors , Crystals
Topics	Nanotechnology and Nanomaterials , Graphene and 2D Materials
Industry	Research & Laboratory