Experimental study and modeling of atomic-scale friction in zigzag and armchair lattice orientations of MoS₂

Abstract

Physical properties of two-dimensional materials, such as graphene, black phosphorus, molybdenum disulfide (MoS₂) and tungsten disulfide, exhibit significant dependence on their lattice orientations, especially for zigzag and armchair lattice orientations. Understanding of the atomic probe motion on surfaces with different orientations helps in the study of anisotropic materials. Unfortunately, there is no comprehensive model that can describe the probe motion mechanism. In this paper, we report a tribological study of MoS₂ in zigzag and armchair orientations. We observed a characteristic power spectrum and friction force values. To explain our results, we developed a modified, two-dimensional, stick-slip Tomlinson model that allows simulation of the probe motion on MoS₂ surfaces by combining the motion in the Mo layer and S layer. Our model fits well with the experimental data and provides a theoretical basis for tribological studies of two-dimensional materials.

Keywords:

• MoS₂
• atomic-scale friction
• two-dimensional model
• lattice orientation

Classification:

• 40 Optical, magnetic and electronic device materials
• 105 Low-Dimension (1D/2D) materials
• 100 Materials
• 212 Surface and interfaces
• 200 Applications
• 303 Mechanical / Physical processing
• 300 Processing / Synthesis and Recycling

Disclosure statement

No potential conflict of interest was reported by the authors.

Acknowledgments

We thank the Shanghai Institute of Optics and Fine Mechanics for the preparation of MoS₂ films.