Mechanical properties of β-Si₃N₄ thin layers in basal plane under tension: A molecular dynamics study

The mechanical properties and failure mechanisms of the β-Si ₃N₄ thin layers in basal plane under uniaxial tension are investigated by using molecular dynamics simulations. It is found that the thin layers display a nonlinear stress-strain relationship first at ε < 0.06, and then a linear response at 0.06 < ε < 0.09, and finally the stresses increase nonlinearly with the strains until fracture occurs. The fracture stresses and strains increase with increasing the side lengths of the thin layers, and the trend is same for Young's moduli accompanying little anisotropy. The deterioration in mechanical properties derives from the N ^6h-Si bonds where the fracture is initiated.