Investigation of Nanomechanical Properties of β-Si₃N₄Thin Layers in a Prismatic Plane under Tension: A Molecular Dynamics Study

We report molecular dynamics simulations of the nanomechanical properties and fracture mechanisms of β-Si3N4 thin layers in a prismatic plane under uniaxial tension. It is found that the thin layers in the y loading direction display a linear stress-strain relationship at ε < 0.021, and afterward, the stress increases nonlinearly with the strain until fracture occurs. However, for the z direction, the linear response is located at ε < 0.051. The calculated fracture stresses and strains of the thin layers increase with strain rates both in both directions. The thin layers exhibit the higher Young's modulus of 0.345 TPa in the z direction, higher than that in the y direction. The origins of crack derive from N(2c-1)-Si and N(6h-1)-Si bonds for the y and z loading directions, respectively.