First-principles calculations of the mechanical properties of boron-rich compounds B12N2X (X = Be, Zn, Cd)

Abstract

Using first-principles calculations, we have investigated the mechanical properties (bulk, shear, and Young's moduli, Poisson's ratio, and brittleness) of boron-rich compounds B12N2X (X = Be, Zn, Cd) with the boron carbide-type structure. The higher shear modulus, 221 GPa for B 12N2Be, and the unusual ratio of shear modulus to bulk modulus suggest that the boron-rich compound B12N2Be is a superhard material. The ionicity of B-X bonds increases with the introduction of metal atoms from Be to Zn to Cd. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA.