Abstract
First-principle calculations are performed to investigate the structural, elastic, and electronic properties of and . The calculated equilibrium structural parameters of are consistent with the available experimental data. The calculations indicate that in the space group is more energetically stable under the ambient condition than in the . Based on the calculated bulk modulus, shear modulus of polycrystalline aggregate, and can be regarded as potential candidates of ultra-incompressible and hard materials. Furthermore, the elastic anisotropy is discussed by investigating the elastic stiffness constants. Density of states and electron density analysis unravel the covalent bonding between the transition metal atoms and the boron atoms as the driving force of the high bulk modulus and high shear modulus as well as small Poisson's ratio.
- Received 15 August 2006
DOI:https://doi.org/10.1103/PhysRevB.74.224112
©2006 American Physical Society