▎ 摘　　要

Si2BN has been recently predicted theoretically as a new entirely planar two-dimensional material with a honeycomblike structure (like graphene), which is stable even at T > 1000 K. In the present paper, we study the structural deformations and mechanical properties of Si2BN and graphene under both uniaxial (along the direction of the arm chair and zigzag chains) and uniform biaxial tensile strain till the fracture limit and we compare those properties of the two structures with each other. According to our findings, in the Si2BN structure, Si-Si and Si-B bonds are weaker than B-N and Si-N bonds, respectively, contrary to graphene bonds, which all have the same strength. In particular, B-N bond lengths of Si2BN remain almost unchanged under the strain conditions we studied, not exceeding approximate to 6% of their initial length. Si2BN was found to be anisotropic, exhibiting large Young's and biaxial modulus values of the order of 1/3 and 2/5 of that of graphene, respectively. The different bond strengths in Si2BN explains its anisotropy and makes it behave very differently under strain when compared to graphene.