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Characterization of a Microscale Superlubric Graphite Interface

Kunqi Wang, Cangyu Qu, Jin Wang, Baogang Quan, and Quanshui Zheng
Phys. Rev. Lett. 125, 026101 – Published 9 July 2020
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Abstract

Direct characterizations of the two component surfaces of a solid-solid interface are essential for understanding its various interfacial mechanical, physical, and electrical behaviors. Particularly, the fascinating phenomenon termed structural superlubricity, a state of nearly zero friction and wear, is sensitively dependent on the interface structure. Here we report a controllable pick-and-flip technique to separate a microscale contact pair for the characterization of its two component surfaces for van der Waals layered materials. With this technique, the interface of a graphite superlubric contact is characterized with resolution from microscale down to the atomic level. Imaging of the graphite lattice provides direct proof that this superlubric interface consists of two monocrystalline surfaces incommensurate with each other. More importantly, the structure-property relationship for this contact is investigated. Friction measurements combined with fully atomistic molecular dynamics reveal that internal structures [internals steps, pits, and bulges buried underneath the topmost graphene sheet(s)] have negligible contribution to the total friction; in contrast, external defects lead to a high friction. These results help us to better understand the structure of highly oriented pyrolytic graphite and the fundamental mechanisms of structural superlubricity, as well as to guide the design of superlubricity-based devices.

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  • Received 9 February 2020
  • Accepted 17 June 2020

DOI:https://doi.org/10.1103/PhysRevLett.125.026101

© 2020 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Kunqi Wang1,2, Cangyu Qu2,3,4,*, Jin Wang2,4, Baogang Quan5, and Quanshui Zheng1,2,3,4,†

  • 1State Key Laboratory of Tribology & Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
  • 2Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084, China
  • 3Institute of Superlubricity Technology, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057, China
  • 4Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China
  • 5Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

  • *Corresponding authors. qucy@tsinghua-sz.org
  • Corresponding authors. zhengqs@tsinghua.edu.cn

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Issue

Vol. 125, Iss. 2 — 10 July 2020

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