First principle calculations of elastic and thermodynamic properties of Ir3Nb and Ir3V with L12 structure under high pressure

Abstract The structural and elastic properties of the L12 structure Ir3Nb and Ir3V under pressure have been investigated by means of the first principles calculations based on the density functional theory within the generalized gradient approximation. The lattice parameters of Ir3Nb and Ir3V obtained by minimization of the total energy are consistent with the available experimental and other theoretical results. In addition, the elastic constants (C11, C12, C44) of Ir3Nb and Ir3V show that they are mechanical stable structures under pressure. The values of B/G exhibit an upward trend with increasing pressure, which means its ductility increased. When the pressure reaches 45 GPa, the Cauchy pressures and B/G values reveal that Ir3Nb and Ir3V change from brittle to ductile. Finally, through quasi-harmonic Debye model, the temperature and pressure dependences of thermodynamic properties are predicted in a wide pressure (0–50 GPa) and temperature (0–1200 K) ranges.