Mechanical response to axial strain in WS2 nanotubes

In order to take advantage of inorganic nanotubes for their use with pragmatic purposes, characterization of their mechanical properties becomes a relevant issue. In the present study, a series of results on the mechanical properties of WS2 nanotubes of several diameters and two main lattice orientations was obtained by the implementation of molecular dynamics simulations using an interatomic potential of the Stillinger-Weber kind. A Young's modulus for nanotubes of H polytype close to 170 GPa was obtained in accordance with experimental results, and of approximate to 130 GPa for nanotubes of the T polytype, with almost no dependance on the diameter of the nanotube. The tensile strength was as large as 20 GPa (H armchair nanotubes, close to the value obtained in experiments), and the strain at the point of rupture reached values close to 0.24. The effect of several kinds of defects on the mechanical properties was investigated, and the results showed that when the defects consisted in the absence of a whole WS2 unit, the tensile strength and point of rupture dropped considerably, and the fracture became more brittle than in pristine nanotubes. The dependence of the mechanical properties on temperature was also investigated.