Mechanical Properties of Monolayer Molybdenum Disulfide

Abstract

We use atomistic simulations to study mechanical properties of monolayer molybdenum disulfide MoS2. Using molecular dynamic (MD) simulations, we investigate the nano-fracture properties of monolayer MoS2 under mixed mode I and II loadings. The MD simulations are used to obtain the critical stress intensity factors of both armchair and zigzag cracks as a function of applied loading phase angle. Our atomistic simulations predict that armchair cracks are tougher than zigzag cracks, and both armchair and zigzag cracks tend to propagate along a zigzag path. Furthermore, we use density functional theory (DFT) to investigate how point defects influence the mechanical properties of nanoribbons. Our DFT simulations show that missing one S atom does not significantly affect the mechanical strength of monolayer MoS2, whereas missing one Mo atom can reduce the maximum strength of single layer MoS2 sheet by about 10%.

Relationships between the elastic and fracture properties of boronitrene and molybdenum disulfide and those of graphene

“…An important question is the validity of the Griffith relationship at short length scales around and below 1 nm, as already studied by several groups for graphene [35]. [20,33,55,56]), line (edge) energy (h-BN: [45,46], MoS 2 : [10,62]), fracture toughness (h-BN: [15], MoS 2 : [18,63]), and strain energy release rate (values were calculated from the line energies) of boronitrene and MoS 2 with those of graphene [44]. Results derived by the bond-breaking model from the mean stiffness and strength values are assigned by stars.…”

“…It is worth noting the large anisotropy of the fracture strength in MoS 2 . The ultimate critical strength of MoS 2 has been assigned to zigzag edges [20,33,55,56].…”

“…With the average mechanical properties E 2D = 131 N m −1 , s m 2D =9.8 N m −1 , and γ 1D =0.71 nJ m −1 formally an average 2D fracture toughness with the dimension N m −1/2 and the 2D strain energy release rate (nJ m −1 ) can be estimated. Using the bond-breaking model we can define the [39][40][41]43] and MoS 2 [20,33,55,56], as well as MD simulations of defective h-BN [27][28][29] and defective MoS 2 [20,33,56,67] versus the square root of half the defect size in comparison with graphene data [44]. The dashed lines are to guide the eye.…”

“…Figure 4. DFT calculations of the critical fracture strengths of pristine h-BN[39][40][41]43] and MoS 2[20,33,55,56], as well as MD simulations of defective h-BN[27][28][29] and defective MoS 2[20,33,56,67] versus the square root of half the defect size in comparison with graphene data[44]. The dashed lines are to guide the eye.…”