Insight into the nanomechanical properties under indentation of β-Si3N4 nano-thin layers in the basal plane using molecular dynamics simulation

Abstract

Molecular dynamics simulations were performed to clarify the nanomechanical responses of β-Si₃N₄ nano-thin layers in the basal plane for indenters of various radii, different indentation velocities and at different temperatures. It was found that the maximum loading stress and indenter displacement both increase with increasing radius of the indenter. A large number of N^6h–Si bond-breaking defects and one N^2c–Si bond-breaking defects are responsible for the initiation of fracturing. With increasing loading velocity, the maximum loading stresses show almost no change; however, a high loading velocity can shorten the displacement of the indenter and contributes to the formation of new N^2c–Si bond-breaking defects. Thermal fluctuations can decrease the mechanical properties of the thin layer. The maximum loading stresses and indenter displacements are sensitive to both the radius of the indenter and the loading temperature.