Structural, elastic, electronic and hardness properties of osmium diboride predicted from first principles calculations

Using particle swarm optimization algorithm, we predicted two new atmospheric phases and two new high pressure phasess for OsB2 in the pressure range from 0 to 100 GPa. By first-principles calculations with density functional theory, we further investigate the structure, phase stability, elastic properties, hardness, electronic properties for these structures. Results show that they are all thermodynamically and mechanically stable. The calculations of the enthalpy-pressure relationship was calculated to discuss the possible phase transition of OsB2 at high pressure condition. The bulk modulus, shear modulus, Young's modulus and Poisson's ratio were computed to discuss their elastic properties. The calculations of hardness show that they are all hard materials. Especially for atmospheric I4/mmm phase and high pressure Fddd phase, their hardness are larger than 32 GPa, not far from the hardness of superhard materals. Density of states and charge density of various OsB2 phases were presented to explore the reason for their high hardness. (C) 2020 Elsevier B.V. All rights reserved.