Abstract
The structural, mechanical, and electronic properties of , , and have been studied by performing first-principles calculations at the level plane-wave basis pseudopotential formalism in both aluminum diboride- and rhenium diboride-type structures. The results of local density approximation and generalized gradient approximation indicated that all three of hexagonal structures within rhenium diboride-type are energetically favorable than those of aluminum diboride-type, they are mechanically stable and also hard materials. In addition to electronic properties of highly directional covalent bonds, optimal filling of bonding states, mechanical properties, and also the Debye temperature of the structures support that the rhenium diboride-type hexagonal phase of is harder than the others. Interestingly, instead of other five structures, only within aluminum diboride-type hexagonal structure has a finite magnetic moment at the equilibrium geometry.
- Received 19 December 2008
DOI:https://doi.org/10.1103/PhysRevB.80.134107
©2009 American Physical Society