The crystal structure of IrB2: a first-principle calculation

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.