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Topology and polarity of dislocation cores dictate the mechanical strength of monolayer MoS_2

Wu, Jianyang and Gong, Hao and Zhang, Zhisen and He, Jianying and Ariza, Pilar and Ortiz, Michael and Zhang, Zhiliang (2019) Topology and polarity of dislocation cores dictate the mechanical strength of monolayer MoS_2. Applied Materials Today, 15 . pp. 34-42. ISSN 2352-9407. https://resolver.caltech.edu/CaltechAUTHORS:20190114-093259803

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Abstract

In contrast to homoelemental graphene showing common dislocation dipole with pentagon-heptagon (5|7) core, heteroelemental MoS2 is observed to contain diverse dislocation cores that tune the chemical and physical properties. Yet, how the inevitable dislocation cores in MoS_2 affect the mechanical behaviours remains virtually unexplored. Herein, we report direct atomistic simulations of mechanical characteristics of isolated dislocation-embedded MoS_2 monolayers under tensile load. All isolated dislocation cores in MoS_2 monolayer rise polar stress-concentration, while those with larger Burgers vector are less energetically-favorable configurations but show local wrinkling behaviour. It is revealed that the intrinsic tensile strength of MoS_2 is dictated by topology and polarity of dislocation cores. There is a strong inverse correlation between the maximum residual stresses induced by the dislocation cores and the strength of MoS_2 monolayers. Mechanical failure initiates from the bond at dislocation polygon on which side there is a missing atomic chain. Armchair-oriented 4|8 dislocation exhibits sole brittle failure, however, dual brittle/ductile fractures occur in zigzag-oriented dislocations; Mo-S-Mo angle-oriented crack is brittle, while the S-Mo-S angle-oriented crack becomes ductile. Our findings shed sights on mechanical design of heteroelemental 2D materials via dislocation engineering for practical application.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.apmt.2018.12.019DOIArticle
Alternate Title:Topology and polarity of dislocation cores dictate the mechanical strength of monolayer MoS2
Additional Information:© 2019 Elsevier Ltd. Received 13 October 2018, Revised 30 November 2018, Accepted 31 December 2018, Available online 12 January 2019.
Subject Keywords:Monolayer MoS2; Dislocation cores; Molecular dynamics simulations; Mechanical strength; Fracture characteristics
Record Number:CaltechAUTHORS:20190114-093259803
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20190114-093259803
Official Citation:Jianyang Wu, Hao Gong, Zhisen Zhang, Jianying He, Pilar Ariza, Michael Ortiz, Zhiliang Zhang, Topology and polarity of dislocation cores dictate the mechanical strength of monolayer MoS2, Applied Materials Today, Volume 15, 2019, Pages 34-42, ISSN 2352-9407, https://doi.org/10.1016/j.apmt.2018.12.019. (http://www.sciencedirect.com/science/article/pii/S2352940718305936)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92248
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:14 Jan 2019 20:44
Last Modified:03 Oct 2019 20:42

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