The dynamical stability, electronic, elastic properties and ideal strength of diamond-like cubic B2CN: A first-principles study

Abstract

The structural stability, electronic and mechanical properties of the cubic diamond-like B2CN (c-B2CN) are systematically studied by first-principles calculations. It was found dynamically and mechanically stable at ambient pressure evidenced by no soft phonon mode and all of the elastic constants satisfy the Born-Huang criteria. c-B2CN shows hole-type conducting behavior. It has high bulk modulus (460 GPa) but relatively lower shear modulus (355 GPa) implied that it has outstanding ability to defend volume deformation but weaker ability to resist shearing forces. The calculated hardness is higher than the superhard threshold of 40 GPa, but the lowest ideal strength of 32.8 GPa along the shear direction of (111)[1‾1‾2] is much weaker which implied that it could not be as hard as it was expected.