| Due to its intrinsic direct bandgap semiconductor,SLMoS2 has many outstanding physical and chemical properties and has broad application prospects in nanoelectronic devices,energy storage,chemical catalysis and nanofiltration membranesintegrated fields.However SLMoS2 films prepared by physical vapor deposition,chemical vapor deposition and mechanical exfoliation methods exist more or less various defects or grain boundaries in terms of preparation,characterization and processing,which have significant influence on its thermal conductivity,electrical contacts,band-to-band tunneling,photoluminescence,magnetism and mechanical properties.Mechanical properties of SLMoS2 are one of the decisive influence parameters,which plays an important role in the practical engineering application.Therefore,the study of the effect of defects on the mechanical properties of SLMoS2 has practical engineering application value and significance of scientific research.In this paper,molecular dynamics simulation method is used to report the influence of vacancy defect on the mechanical properties of SLMoS2.In order to understand the significant issue of the interatomic potential function in the simulation of Mechanical properties of SLMoS2 with vacancy defects,the differences of the two kinds of potential functions,refering to REBO and SW potential functions,are discussed in terms of structural geometrical parameters,defect formation energy,lattice twist,thermal expansion coefficient,melting temperature,and Young's modulus using the molecular dynamics simulation method.It is found that the REBO potential function can better characterize the mechanical properties of SLMoS2 with vacancy defects than SW potential energy functions.SLMoS2 with four kinds of vacancy defects was simulated by the REBO potential function to understand the effects of defect concentration,defect location,chiral and temperature on the mechanical parameters.The results indicate that the tensile elastic modulus of SLMoS2 gradually decrease with the increase of the defect concentration,even its decreasing trend is independent of the defect arrangement.However,the tensile strength tends to remain constant with the increase of the defect concentration for the defect orderly distributed.For SLMoS2 with the random distribution of defects,the tensile properties reflect a slight chiral effect.An anomalous parabolic relationship between the elastic modulus and the temperature is found in the monolayer MoS2 containing 0.1%vacancy.In other words,Increasing the ambient temperature from 40 K to 800 K,the Young's modulus decreases first and then increases.But its tensile strength decreases with increasing temperature.The influence of the defect direction and distance on the tensile mechanical properties and fracture behavior are discussed for VMoS3 models with the five kinds of defect location.The results show when the orientation of the defect is parallel to the stretching direction,the tensile strength is the largest.In turn,perpendicular to the direction of stretching,its tensile strength is the smallest.The five models have a roughly equivalent elastic modulus for SLMoS2 with the small defect concentration.The crack propagation direction of the tensile fracture at low concentration is not related to the arrangement of the defect.However,at high concentrations,the decrease in the spacing of defects and the increase of the defect concentration lead to the direction of crack propagation roughly along the direction of the defect location in the zigzag direction tensile.At last,buckling characteristics between the perfect SLMoS2 and graphene were compared.Based on Euler theory,continuous mechanics method and the material constitutive equation,equivalent thickness and bending stiffness of SLMoS2 are obtained,which the values obtained are consistent with the existing literature reported.In addition,the effects of strain rate and model size on buckling behavior,unloading behavior and lattice transformation are also demonstrated. |
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