Mechanical properties of monolayer ternary transitional metal dichalogenides MoS2xTe2(1 − x): A molecular dynamics study

In this paper, the mechanical behaviors of recently synthesized monolayer ternary transitional metal dichalogenides (TMDs) MoS2xTe2(1 − x) (0 < x < 1) under tensile loading are studied by classical molecular dynamics simulations. Particular attention is paid to the fundamental mechanical properties such as Young's modulus and fracture behaviors of monolayer MoS2xTe2(1 − x). Our results show that Young's modulus of monolayer MoS2xTe2(1 − x) remains almost unchanged when the stoichiometric coefficient x is in the range of 0–0.4 but increases apparently when x increases from 0.4 to 1. In terms of their fracture behaviors, the alloyed ternary TMDs are found to show a ductile fracture feature, which is distinctly different from the brittle fracture behavior observed in their pristine binary TMD counterparts. The ultimate strength of alloyed ternary TMDs is found to be much lower than that of the pristine binary TMDs, which is attributed to the unaccommodated deformation caused by the stress concentration between Te atoms and nearby S atoms. The influence of loading direction and temperature on the aforementioned mechanical properties is also examined. It is found that Young's modulus and the ultimate strength of monolayer MoS2xTe2(1 − x) generally decrease with increasing temperature due to the temperature-induced softening effect. In the biaxial tensile test, Young's modulus and ultimate strength are found to be isotropic. The aforementioned mechanical parameters of monolayer MoS2xTe2(1 − x) under biaxial loading are significantly smaller than those under uniaxial loading. The present work is expected to significantly expand the knowledge of the mechanics of ternary TMDs and facilitate their applications in bandgap engineering.