Structural, mechanical and thermodynamic properties of AuIn2 crystal under pressure: A first-principles density functional theory calculation

Abstract

The structural, mechanical and thermodynamic properties of cubic AuIn2 crystal in the cubic fluorite structure, and also their temperature, hydrostatic pressure and direction dependences are investigated using first-principles calculations based on density functional theory (DFT) within the generalized gradient approximation (GGA). The optimized lattice constants of AuIn2 single crystal are first evaluated, by which its hydrostatic pressure-dependent elastic constants are also derived. Then, the hydrostatic pressure-dependent mechanical characteristics of the single crystal, including ductile/brittle behavior and elastic anisotropy, are explored according to the characterized angular character of atomic bonding, Zener anisotropy factor and directional Young’s modulus. Moreover, the polycrystalline elastic properties of AuIn2, such as bulk modulus, shear modulus and Young’s modulus, and its ductile/brittle and microhardness characteristics are assessed versus hydrostatic pressure. Finally, the temperature-dependent Debye temperature and heat capacity of AuIn2 single crystal are investigated by quasi-harmonic Debye modeling.The present results reveal that AuIn2 crystal demonstrates low elastic anisotropy, low hardness and high ductility. Furthermore, its heat capacity strictly follows the Debye T3-law at temperatures below the Debye temperature, and reaches the Dulong–Petit limit at temperatures far above the Debye temperature.