Lattice-resolved frictional pattern probed by tailored carbon nanotubes

Abstract

In this study, we demonstrate a high-resolution friction profiling technique using synchronous atomic/lateral force microscopy (AFM/LFM). The atomic resolution is achieved by our special carbon nanotube (CNT) probes made via in situ tailoring and manipulation inside an ultra-high vacuum transmission electron microscope (UHV TEM). The frictional pattern mapped on graphite displays a periodic distribution similar to the atomic (0001)-oriented graphite lattice structure. Furthermore, the electrothermal process in the UHV TEM renders a graphite-capped CNT tip, which delivers the nanotribology study within two graphite layers by the LFM measurement on graphite. The synchronous AFM and LFM images can discern a spatial shift between the atomic points and local friction maxima. We further interpret this shift as caused by the lattice distortion, which in turn induces irreversible energy dissipation. We believe this is the origin of atomic friction on the sub-nanonewton scale.

Carbon Nanotube AFM Probe Technology

“…Shortening the CNT probe can decrease the thermal oscillation amplitude. Therefore, short CNT probe is required for the CNT probe's high resolution imaging or applicatons with high lateral force constant requirement, such as friction study (Lai et al, 2010). On the contrary, long CNT probe is useful for the high aspect ratio imaging, e.g., biological samples.…”

Orientation-dependent friction between a carbon nanotube and graphite

“…So, when it is in contact with the graphite sample, the side of the tube having a graphite structure constitutes the experimental setup for a graphite sliding over another graphite surface. 14 Our sample is a highly oriented pyrolytic graphite (HOPG) with an angular spread between the graphite sheets of less than 1 . The contact mode AFM is utilized to keep the normal force of the modified cantilever constant, and its lateral force is detected and recorded during scanning.…”