Studying the mechanical properties of monolayer tungsten disulfide (WS2) nanosheets

Forasmuch as، transition metal dichalcogenides (TMDs) are robust nanomaterials to sustain large strains without fracture، their application in new pliable electronic nanodevices is so appealing. Of these nanomaterials is tungsten disulfide which has specific electrical، optical and sensor properties; and due to possessing a non-planar structure، shows interesting responses under different plane strains. This investigation explores the mechanical properties of a monolayer tungsten disulfide (WS2) such as Young''s modulus، bulk modulus، shear modulus and Poisson''s ratio by applying the density functional theory (DFT) calculations based on the generalized gradient approximation (GGA). The results demonstrate that elastic properties of WS2 are less than those of graphene and its analogous inorganic hexagonal boron-nitride (h-BN) nanosheets. Unlikely، Poisson''s ratio is calculated higher than that of graphene and h-BN nanosheets. It is observed that، due to the special structure of WS2، the thickness of nanosheet (distance between S-S atoms)، bond length of W-S and the angle S-W-S change under different kinds of strains. Also، in the case of biaxial strain، the amount of variations in bond length، thickness and bending angle is higher than that in the cases of uniaxial and shear strain.