Topology and polarity of dislocation cores dictate the mechanical strength of monolayer MoS2

Wu, Jianyang; Gong, Hao; Zhang, Zhisen; He, Jianying; Ariza, Manuel R. Gómez; Ortiz, Michael

doi:10.1016/j.apmt.2018.12.019

Cited by 28 publications

(20 citation statements)

References 48 publications

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“…Remarkably, topological defects such as vacancies, dislocations, and grain boundaries in MoS 2 sheets play an important role in tuning their transport, electronic, and mechanical properties. − In reality, as a result of extra large ratios of surface to bulk in monolayer MoS 2 , topological defects easily tend to be generated . For example, sulfur vacancies, hereafter also called as desulfurization in this work, in the basal plane of MoS 2 are one common type of topological defects.…”

Section: Introductionmentioning

confidence: 98%

Self-Assembly of MoS₂ Monolayer Sheets by Desulfurization

Cao

2021

Langmuir

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Self-assembled structures of two-dimensional (2D) materials exhibit novel physical properties distinct from those of their parent materials. Herein, the critical role of desulfurization on the self-assembled structural morphologies of molybdenum disulfide (MoS2) monolayer sheets is explored using molecular dynamics (MD) simulations. MD results show that there are differences in the atomic energetics of MoS2 monolayer sheets with different desulfurization contents. Both free-standing and substrate-hosted MoS2 monolayer sheets show diversity in structural morphologies, for example, flat plane structures, wrinkles, nanotubes, and folds, depending on the desulfurization contents, planar dimensions, and ratios of length to width of MoS2 sheets. Particularly, at the critical desulfurization content, they can roll up into nanotubes, which is in good agreement with previous experimental observations. Importantly, these observed differences in the molecular structural morphologies between free-standing and substrate-hosted MoS2 monolayer sheets can be attributed to interatomic interactions and interlayer van der Waals interactions. Furthermore, MD results have demonstrated that the surface-driven stability of MoS2 structures can be indicated by the desulfurization contents on one surface of MoS2 monolayer sheets, and the self-assembly of MoS2 monolayer sheets by desulfurization can emerge to adjust their surface-driven stability. The study provides important atomic insights into tuning the self-assembling structural morphologies of 2D materials through defect engineering in the future science and engineering applications.

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Section: Introductionmentioning

confidence: 98%

Self-Assembly of MoS₂ Monolayer Sheets by Desulfurization

Cao

2021

Langmuir

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“…Moreover, as a result of its bielemental composition, polar 5|7 dislocation can be Mo-and S-oriented, with pentagon and heptagon rings shared by Mo−Mo and S−S bonds, respectively, which are marked as Mo5|7 and S5|7, respectively. 25 To quantitatively characterize both zigzag-and armchair-tilt twin GB structures of MoS 2 , the tilt angle (θ) of twin GBs is defined. For zigzag-tilt twin GB structures, the tilt angle θ is determined as…”

Section: ■ Atomic Models and Methodologymentioning

confidence: 99%

“…54 Such MoS 2 -type REBO force field has been successfully utilized to mimic the mechanical characteristics of various MoS 2 nanostructures. 5,25,46,55 ■ RESULTS AND DISCUSSION GB Energy in SLMoS 2 . Figure 2 summarizes the GB energy for Mo5|7, S5|7, and Mo5|7 + S5|7 dislocation-dominated GBs with θ from 5.06/42.03 to 21.98/54.25°for the armchair/zigzag interface.…”

Section: ■ Atomic Models and Methodologymentioning

confidence: 99%

“…For instance, SLMoS 2 with armchair 4−8 dislocations present completely brittle fracture, but with zigzagoriented dislocations, it exhibits characteristic dual brittle/ ductile fractures. 25 Under nanoindentation, SLMoS 2 with a unique 4|4, 4|8, or 8|8 GB structure was initially failed at the GBs and the breaking force was found to be independent of GB energy. 2 With regard to the case of grain size, it was intriguingly identified that both the tensile stiffness and tensile strength of polycrystalline SLMoS 2 to the grain size are described by an inverse pseudo Hall−Petch relation.…”

Section: ■ Introductionmentioning

confidence: 97%

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Strengthening and Weakening by Dislocations in Monolayer MoS₂

Liu

Lin

et al. 2021

Chem. Mater.

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Dislocations govern the properties of crystals. Yet, how pentagon–heptagon (5|7) pairs in grain boundaries (GBs) affect the mechanical properties of MoS2 remains poorly known. Using atomistic simulations and the continuum disclination dipole model, we show that depending on the tilt angle and 5|7 dislocation arrangement, MoS2 GB strength can be enhanced or reduced with the tilt angle. For zigzag-tilt GBs primarily composed of Mo5|7 + S5|7 dislocations, GB strength monotonically increases as the square of the tilt angle. For armchair-tilt GBs with Mo5|7 or S5|7 dislocations, however, the trend of GB strength breaks down, as dislocations are unevenly spaced. Moreover, mechanical failure initiates at the bond shared by 5|7 rings, in contrast to graphene in which failure occurs at the bond shared by 6|7 rings. This work provides new insights into the mechanical design of synthetic transition metal dichalcogenide crystals via dislocation engineering.

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“…Two-dimensional TMDs such as MoS 2 have intricate dislocations and GBs due to the polarity of their constituent elements and the flexible Mo–S bonding coordination. Diverse structures of topological dislocations and GBs in TMDs were first predicted by Zou et al , and subsequently validated in experimental observations. − Although the mechanical, − electronic, , and magnetic properties of dislocations and GBs in MoS 2 have been systematically studied via theoretical simulations, the thermal transport through these topological dislocations and GBs is less investigated. Very recently, Sledzinska et al , measured the thermal transport properties of polycrystalline MoS 2 thin films and recorded an extremely low thermal conductivity (∼0.27 W m –1 K –1 at room temperature), which was nearly several hundred times lower than that of the pristine one. − With the aid of finite-element simulation, they attributed this unique phenomenon to the very low thermal conductance of GBs with different orientations.…”

Section: Introductionmentioning

confidence: 95%

Phonon–Grain-Boundary-Interaction-Mediated Thermal Transport in Two-Dimensional Polycrystalline MoS₂

Lin

Chen

Zou

2019

ACS Appl. Mater. Interfaces

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Although dislocations and grain boundaries (GBs) are ubiquitous in large-scale MoS2 samples, their interaction with phonons, which plays an important role in determining the lattice thermal conductivity of polycrystalline MoS2, remains elusive. Here, we perform a systematic study of the heat transport in two-dimensional polycrystalline MoS2 by both molecular dynamics simulation and atomic Green’s function method. Our results indicate that the thermal boundary conductance of GBs of MoS2 is in the range from 6.4 × 108 to 35.3 × 108 W m–2 K–1, which is closely correlated with the overlap between the vibrational density of states of GBs and those of the pristine lattice, as well as the GB energy. It is found that the GBs strongly scatter the phonons with frequency larger than 2 THz, accompanied by a pronounced phonon localization effect and significantly reduced phonon group velocities. Furthermore, by comparing the results from realistic polycrystalline MoS2 to those from different theoretical models, we observe that the Casimir model is broken down and detailed phonon dynamics at a specific GB should be taken into account to accurately describe the phonon transport in polycrystalline materials. Our findings will provide useful guidelines for designing efficient thermoelectric and thermal management materials based on phonon–GB interaction.

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Topology and polarity of dislocation cores dictate the mechanical strength of monolayer MoS2

Cited by 28 publications

References 48 publications

Self-Assembly of MoS₂ Monolayer Sheets by Desulfurization

Self-Assembly of MoS₂ Monolayer Sheets by Desulfurization

Strengthening and Weakening by Dislocations in Monolayer MoS₂

Phonon–Grain-Boundary-Interaction-Mediated Thermal Transport in Two-Dimensional Polycrystalline MoS₂

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Topology and polarity of dislocation cores dictate the mechanical strength of monolayer MoS2

Cited by 28 publications

References 48 publications

Self-Assembly of MoS2 Monolayer Sheets by Desulfurization

Self-Assembly of MoS2 Monolayer Sheets by Desulfurization

Strengthening and Weakening by Dislocations in Monolayer MoS2

Phonon–Grain-Boundary-Interaction-Mediated Thermal Transport in Two-Dimensional Polycrystalline MoS2

Contact Info

Product

Resources

About

Self-Assembly of MoS₂ Monolayer Sheets by Desulfurization

Self-Assembly of MoS₂ Monolayer Sheets by Desulfurization

Strengthening and Weakening by Dislocations in Monolayer MoS₂

Phonon–Grain-Boundary-Interaction-Mediated Thermal Transport in Two-Dimensional Polycrystalline MoS₂