The crystal structure of IrB2: a first-principle calculation

Abstract

First-principle calculations were performed to investigate the structural, elastic, and electronic properties of iridium diboride (IrB₂). It was demonstrated that the new phase of IrB₂ belongs to the monoclinic C2/m space group, and we have named it m-IrB₂. Its structure is energetically much superior to the recently proposed Pmmn-type IrB₂. Further calculations of phonon and elastic constants confirm that m-IrB₂ is dynamically and mechanically stable. The calculated high shear modulus reveals that it is a potentially a material of low compressibility. An analysis of the density of its states and chemical bonding show that the strongly directional covalent B–B and B–Ir bonds in m-IrB₂ make a considerable contribution to its stability.