Speaker
Description
Molybdenum disulfide (MoS$_2$) is widely used in lubrication, electronics, catalysis, batteries, and sensing.Those applications require the material to withstand stress, deformation or wear. Understanding the fracture and failure mechanisms of MoS$_2$ under these conditions is essential for improving its performance and reliability. The mechanical behavior of MoS$_2$ is influenced by the orientation of its crystal structure, yet most existing studies focus on perfect or polycrystalline forms. Since MoS$_2$ is often prepared through some deposition process as an amorphous material, it is important to explore the degree of order/disorder in the system from fully amorphous to perfect crystal. In this work, we employ reactive molecular dynamics simulations to investigate the effect of degree of crystallinity on the fracture and failure mechanisms of MoS$_2$. Our goal is to provide a deeper understanding of the mechanical behavior of MoS$_2$ and will help optimize its design for industrial applications. Different levels of disorder are achieved by controlling annealing and quenching temperatures in the model generation process. To investigate the fracture process, a uniaxial tension boundary condition is applied on MoS$_2$ sheet with a crack at the center. Our results show a transition from brittle to ductile behavior as the disorder of the structure increases. In various polycrystalline MoS$_2$ models, we pay special attention to the effect of grain boundaries on the crack propagation path. Further, the underlying mechanics leading to the fracture process and failure of MoS$_2$ are quantified and studied in detail.
