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Overcoming nanoscale friction barriers in transition metal dichalcogenides

Overcoming nanoscale friction barriers in transition metal dichalcogenides
Overcoming nanoscale friction barriers in transition metal dichalcogenides
We study the atomic contributions to the nanoscale friction in layered MX2 (M = Mo, W; X = S, Se, Te) transition metal dichalcogenides by combining ab initio techniques with group theoretical analysis. Starting from stable atomic configurations, we propose a computational method, named {Normal-Modes Transition Approximation} (NMTA), to individuate possible sliding paths from only the analysis of the phonon modes of the stable geometry. The method provides a way to decompose the atomic displacements realizing the layer sliding in terms of phonon modes of the stable structure, so as to guide the selection and tuning of specific atomic motions promoting MX2 sheets gliding, and to adjust the corresponding energy barrier. The present results show that main contributions to the nanoscale friction are due to few low frequency phonon modes, corresponding to rigid shifts of MX2 layers. We also provide further evidences that a previously reported Ti-doped MoS2 phase is a promising candidate as new material with enhanced tribologic properties. The NMTA approach can be exploited to tune the energetic and the structural features of specific phonon modes, and, thanks to its general formulation, can also be applied to any solid state system, irrespective of the chemical composition and structural topology
Friction, sliding, phonon, transition metal dichalcogenides, energy barrier, cophonicity
2469-9950
Cammarata, Antonio
d9f02172-7364-4d80-a32b-03d2d7970257
Polcar, Tomas
c669b663-3ba9-4e7b-9f97-8ef5655ac6d2
Cammarata, Antonio
d9f02172-7364-4d80-a32b-03d2d7970257
Polcar, Tomas
c669b663-3ba9-4e7b-9f97-8ef5655ac6d2

Cammarata, Antonio and Polcar, Tomas (2017) Overcoming nanoscale friction barriers in transition metal dichalcogenides. Physical Review B. (doi:10.1103/PhysRevB.96.085406).

Record type: Article

Abstract

We study the atomic contributions to the nanoscale friction in layered MX2 (M = Mo, W; X = S, Se, Te) transition metal dichalcogenides by combining ab initio techniques with group theoretical analysis. Starting from stable atomic configurations, we propose a computational method, named {Normal-Modes Transition Approximation} (NMTA), to individuate possible sliding paths from only the analysis of the phonon modes of the stable geometry. The method provides a way to decompose the atomic displacements realizing the layer sliding in terms of phonon modes of the stable structure, so as to guide the selection and tuning of specific atomic motions promoting MX2 sheets gliding, and to adjust the corresponding energy barrier. The present results show that main contributions to the nanoscale friction are due to few low frequency phonon modes, corresponding to rigid shifts of MX2 layers. We also provide further evidences that a previously reported Ti-doped MoS2 phase is a promising candidate as new material with enhanced tribologic properties. The NMTA approach can be exploited to tune the energetic and the structural features of specific phonon modes, and, thanks to its general formulation, can also be applied to any solid state system, irrespective of the chemical composition and structural topology

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Accepted/In Press date: 12 July 2017
e-pub ahead of print date: 3 August 2017
Published date: 15 August 2017
Keywords: Friction, sliding, phonon, transition metal dichalcogenides, energy barrier, cophonicity

Identifiers

Local EPrints ID: 412543
URI: https://eprints.soton.ac.uk/id/eprint/412543
ISSN: 2469-9950
PURE UUID: f43aacba-093e-49ca-9d5f-9c7e577f3bc7
ORCID for Tomas Polcar: ORCID iD orcid.org/0000-0002-0863-6287

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Date deposited: 20 Jul 2017 16:30
Last modified: 14 Mar 2019 01:36

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