An ab initio study of the ideal tensile and shear strength of single-crystal β-Si3N4

In this study, the ideal tensile and shear strength of single-crystal beta-Si3N4 was calculated using an ab initio density functional technique. The stress-strain curve of the silicon nitride polymorph was calculated from simulations of uniaxial strain deformation. In particular, the ideal strength calculated for an applied is an element of(11) tensile strain was estimated to be approximately 57 GPa. Recently, a good correlation was reported between the shear modulus of high-strength materials and the experimentally determined Vickers indentation hardness value. Using the reported correlation an estimate was made of the Vickers indentation hardness of single-crystal beta-Si3N4: approximately 20.4 GPa.