Effect of triangular pits on the mechanical behavior of 2D MoTe2: a molecular dynamics study

Context

Among two-dimensional (2D) materials, transition metal dichalcogenides (TMDs) stand out for their remarkable electronic, optical, and chemical properties. Their atomic thinness also imparts flexibility, making them ideal for flexible and wearable devices. However, our understanding of the mechanical characteristics of molybdenum ditelluride (MoTe₂), particularly with defects such as pits, remains limited. Such defects, common in grown TMDs, degrade the mechanical properties and affect electronic and magnetic behaviors. This study uses molecular dynamics (MD) simulations of uniaxial and biaxial tensile loading performed on monolayer molybdenum ditelluride sheets of 2H phase containing triangular pits of varying vertex angles to investigate their fracture properties and visualize their crack propagation. From the stress–strain relationship, Young’s modulus, fracture strain, ultimate tensile strength, and toughness for comparative analysis were calculated.

Method

Tensile loading simulations were performed in molecular dynamics (MD) software LAMMPS, using the Stillinger–Weber (SW) interatomic potential, under strain rate 10⁸ s⁻¹ at room temperature (300 K). From the stress–strain relationship obtained, we calculated Young’s modulus, fracture strain, ultimate tensile strength, and toughness. Results showed that variations in pit edge length, angle, and perimeter significantly affected these properties in monolayer MoTe₂. Regulated alteration of pit angle under constant simulation conditions resulted in improved uniaxial mechanical properties, while altering pit perimeters improved biaxial mechanical properties. Stress distribution was visualized using OVITO software. MoTe₂ with pit defects was found to be more brittle than its pristine counterpart. This study provides foundational knowledge for advanced design strategies involving strain engineering in MoTe₂ and similar TMDs.