title: Observation of high-speed microscale superlubricity in graphite.
abstract: A sheared microscopic graphite mesa retracts spontaneously to minimize interfacial energy. Using an optical knife-edge technique, we report first measurements of the speeds of such self-retracting motion (SRM) from the mm/s range at room temperature to 25 m/s at 235°C [corrected]. This remarkably high speed is comparable with the upper theoretical limit found for sliding interfaces exhibiting structural superlubricity. We observe a strong temperature dependence of SRM speed which is consistent with a thermally activated mechanism of translational motion that involves successive pinning and depinning events at interfacial defects. The activation energy for depinning is estimated to be 0.1-1 eV.
authors.affiliation: Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China.
authors.forename: Jiarui
authors.initials: J
authors.lastname: Yang
authors.forename: Ze
authors.initials: Z
authors.lastname: Liu
authors.forename: Francois
authors.initials: F
authors.lastname: Grey
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Xu
authors.forename: Xide
authors.initials: X
authors.lastname: Li
authors.forename: Yilun
authors.initials: Y
authors.lastname: Liu
authors.forename: Michael
authors.initials: M
authors.lastname: Urbakh
authors.forename: Yao
authors.initials: Y
authors.lastname: Cheng
authors.forename: Quanshui
authors.initials: Q
authors.lastname: Zheng