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Atomically Sharp Crack Tips in Monolayer MoS2 and Their Enhanced Toughness by Vacancy Defects
Shanshan Wang1, Zhao Qin2, Gang Seob Jung2
1Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom.
ACS Nano
|September 23, 2016
Summary
We investigated brittle fracture in 2D monolayer molybdenum disulfide (MoS2). Defects alter crack propagation and fracture mechanisms, showing MoS2
Area of Science:
- Materials Science
- Mechanical Engineering
- Condensed Matter Physics
Background:
- Understanding fracture mechanics in 2D materials is crucial for their application.
- Previous studies on thicker materials limit fundamental insights into fracture processes.
- Molybdenum disulfide (MoS2) is a key 2D material with potential applications.
Purpose of the Study:
- To investigate brittle fracture mechanisms in 2D monolayer MoS2.
- To explore the role of vacancy defects on crack propagation and fracture behavior.
- To compare the fracture toughness of defective MoS2 with graphene.
Main Methods:
- Combined in situ transmission electron microscopy (TEM) for real-time observation.
- Large-scale molecular dynamics (MD) simulations for atomic-level analysis.
- Analysis of crack propagation paths and energy release rates.
Main Results:
- Cracks propagate with atomic sharpness along directions of least energy release.
- Sparse vacancy defects deflect cracks; increased density induces ductile fracture via vacancy migration.
- Defective MoS2 exhibits higher fracture toughness than graphene due to crack-vacancy interactions.
Conclusions:
- Monolayer 2D materials provide a unique platform for fundamental fracture mechanics studies.
- Vacancy defects significantly influence fracture behavior in MoS2, enabling tunable mechanical properties.
- MoS2 offers superior fracture toughness compared to graphene under specific defect conditions.
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