Chirality effect of mechanical and electronic properties of monolayer MoS2 with vacancies

Gan, Yingye; Zhao, Huijuan

doi:10.1016/j.physleta.2014.08.008

Cited by 42 publications

(35 citation statements)

References 33 publications

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“…Young’s modulus can be derived through the second derivative of the strain energy with respect to the strain and can be expressed by Equation (2) [ 24 ]:

where V 0 is the volume of monolayer MoS 2 , the thickness of it is defined as 6.145 Å, and U is the strain energy calculated by subtracting the total energy of the strained system from the equilibrium state. As shown in Figure 5 , the strain–stress curves are plotted for the PL, V1S, and V2S monolayer MoS 2 sheets, respectively.…”

Section: Resultsmentioning

confidence: 99%

First-Principles Study on the Structural and Electronic Properties of Monolayer MoS2 with S-Vacancy under Uniaxial Tensile Strain

et al. 2018

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Monolayer molybdenum disulfide (MoS2) has obtained much attention recently and is expected to be widely used in flexible electronic devices. Due to inevitable bending in flexible electronic devices, the structural and electronic properties would be influenced by tensile strains. Based on the density functional theory (DFT), the structural and electronic properties of monolayer MoS2 with a sulfur (S)-vacancy is investigated by using first-principles calculations under uniaxial tensile strain loading. According to the calculations of vacancy formation energy, two types of S-vacancies, including one-sulfur and two-sulfur vacancies, are discussed in this paper. Structural analysis results indicate that the existence of S-vacancies will lead to a slightly inward relaxation of the structure, which is also verified by exploring the change of charge density of the Mo layer and the decrease of Young’s modulus, as well as the ultimate strength of monolayer MoS2. Through uniaxial tensile strain loading, the simulation results show that the band gap of monolayer MoS2 decreases with increased strain despite the sulfur vacancy type and the uniaxial tensile orientation. Based on the electronic analysis, the band gap change can be attributed to the π bond-like interaction between the interlayers, which is very sensitive to the tensile strain. In addition, the strain-induced density of states (DOS) of the Mo-d orbital and the S-p orbital are analyzed to explain the strain effect on the band gap.

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“…Young’s modulus can be derived through the second derivative of the strain energy with respect to the strain and can be expressed by Equation (2) [ 24 ]:

Section: Resultsmentioning

confidence: 99%

First-Principles Study on the Structural and Electronic Properties of Monolayer MoS2 with S-Vacancy under Uniaxial Tensile Strain

et al. 2018

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“…The monosulfur vacancy (V S ) is the most common point defect, frequently observed in experiments for its lowest formation energy (1.1 eV) [ 7 ]. So far, there are few documents concerning its impacts on the mechanical properties [ 17 , 18 ], which can be momentous in MoS2 engineering applications. Dang and Spearot [ 17 ] conducted molecular dynamics (MD) nanoindentation simulations to investigate the V S effect on the mechanical behavior of monolayer MoS2.…”

Section: Introductionmentioning

confidence: 99%

“…They revealed that the V S defects weaken the breaking force and induce displacive phase transformations under indentation. Gan and Zhao [ 18 ] performed first-principle calculations to show that the chirality effect on the mechanical properties of monolayer MoS2 becomes more and more significant with the increasing of strain, regardless of vacancies. Besides V S , V MoS3 (a vacancy complex of Mo and three nearby S atoms) is another type of defect preferentially generated by the extended electron irradiation [ 7 ].…”

Section: Introductionmentioning

confidence: 99%

The Effect of VMoS3 Point Defect on the Elastic Properties of Monolayer MoS2 with REBO Potentials

Wan

et al. 2016

Nanoscale Res Lett

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Structural defects in monolayer molybdenum disulfide (MoS2) have significant influence on the electric, optical, thermal, chemical, and mechanical properties of the material. Among all the types of structural defects of the chemical vapor phase-grown monolayer MoS2, the VMoS3 point defect (a vacancy complex of Mo and three nearby S atoms) is another type of defect preferentially generated by the extended electron irradiation. Here, using the classical molecular dynamics simulation with reactive empirical bond-order (REBO) potential, we first investigate the effect of VMoS3 point defects on the elastic properties of monolayer MoS2 sheets. Under the constrained uniaxial tensile test, the elastic properties of monolayer MoS2 sheets containing VMoS3 vacancies with defect fraction varying from 0.01 to 0.1 are obtained based on the plane anisotropic constitutive relations of the material. It is found that the increase of VMoS3 vacancy concentration leads to the noticeable decrease in the elastic modulus but has a slight effect on Poisson’s ratio. The maximum decrease of the elastic modulus is up to 25 %. Increasing the ambient temperature from 10 K to 500 K has trivial influences on the elastic modulus and Poisson’s ratio for the monolayer MoS2 without defect and with 5 % VMoS3 vacancies. However, an anomalous parabolic relationship between the elastic modulus and the temperature is found in the monolayer MoS2 containing 0.1 % VMoS3 vacancy, bringing a crucial and fundamental issue to the application of monolayer MoS2 with defects.

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“…41 It should be noted that even though the mechanical properties along different directions are similar at a low strain level, the deformation behaviors at a high strain level depict the significant discrepancy, which consists well with the first-principles calculation of MoS 2 monolayer. 22…”

Section: Results and Discussionmentioning

confidence: 99%

“…21 By making use of the first-principles theory, Young’s moduli of MoS 2 were investigated to be 200.2 ± 0.2 GPa and 200.4 ± 0.4 GPa in armchair and zigzag directions, respectively; the corresponding ultimate strengths were equal to 23.6 GPa and 16.1 GPa. 22 The averaged Young’s modulus of suspended MoS 2 nanosheets was measured to be 330 ± 70 GPa, which was equivalent to graphene oxide. 23 It has been displayed that the mechanical properties of WSe 2 were independent of the layer thickness.…”

Section: Introductionmentioning

confidence: 98%

Machine Learning Enabled Prediction of Mechanical Properties of Tungsten Disulfide Monolayer

et al. 2019

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One of two-dimensional transition metal dichalcogenide materials, tungsten disulfide (WS 2 ), has aroused much research interest, and its mechanical properties play an important role in a practical application. Here the mechanical properties of h-WS 2 and t-WS 2 monolayers in the armchair and zigzag directions are evaluated by utilizing the molecular dynamics (MD) simulations and machine learning (ML) technique. We mainly focus on the effects of chirality, system size, temperature, strain rate, and random vacancy defect on mechanical properties, including fracture strain, fracture strength, and Young’s modulus. We find that the mechanical properties of h-WS 2 surpass those of t-WS 2 due to the different coordination spheres of the transition metal atoms. It can also be observed that the fracture strain, fracture strength, and Young’s modulus decrease when temperature and vacancy defect ratio are enhanced. The random forest (RF) supervised ML algorithm is employed to model the correlations between different impact factors and target outputs. A total number of 3600 MD simulations are performed to generate the training and testing dataset for the ML model. The mechanical properties of WS 2 (i.e., target outputs) can be predicted using the trained model with the knowledge of different input features, such as WS 2 type, chirality, temperature, strain rate, and defect ratio. The mean square errors of ML predictions for the mechanical properties are orders of magnitude smaller than the actual values of each property, indicating good training results of the RF model.

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Chirality effect of mechanical and electronic properties of monolayer MoS2 with vacancies

Cited by 42 publications

References 33 publications

First-Principles Study on the Structural and Electronic Properties of Monolayer MoS2 with S-Vacancy under Uniaxial Tensile Strain

First-Principles Study on the Structural and Electronic Properties of Monolayer MoS2 with S-Vacancy under Uniaxial Tensile Strain

The Effect of VMoS3 Point Defect on the Elastic Properties of Monolayer MoS2 with REBO Potentials

Machine Learning Enabled Prediction of Mechanical Properties of Tungsten Disulfide Monolayer

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