Atomic-scale friction between two graphite surfaces
橫向力顯微鏡 ； 摩擦力 ； 超潤滑 ； LFM ； friction ； superlubricity
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In this study, high-resolution friction profiles are obtained using a commercial synchronous atomic/lateral force microscopy(AFM/LFM) associated with a home-made inertial rotational stepper. This rotational positioning system is applied to revolve the measured sample to defined angular direction, and it is comprised of an inertial rotational stepper and a visual angular measurement. The inertial rotational stepper with diameter 30 mm and height 7.6 mm can be easily attached to the AFM-system built in any general optical microscope, through the feedback control, the angular positioning error is less than 0.01 degree, that can be used to comprehend anisotropic surface properties such as surface friction. The sensitivity of lateral force increase when a cantilever was modified by dual-beam forced ion beam (DB-FIB) system with a lateral force resolution down to several pN. We have studied the energy dissipation between a carbon nanotube tip sliding over a graphite surface in dry contact. In the traditional tribology studies, the unknow tip-sample asperity has always been a critical issue. Here we evidently produced an atomically flat closed cap CNT probe to achieve a single asperity, with a well-defined periodic surface, which allows the complete contact on another atomically flat surface. By measuring atomic-scaled friction force as a function of the rotational angle between two contacting graphite layers, we show that the friction force varies due to the commensurate or incommensurate state between a well-defined carbon nanotube tip and a graphite surface. Our results unambiguously demonstrate the “superlubricity” phenomenon at the atomic scale.
理學院 > 物理學系所