Physical, mechanical, thermodynamic and electronic characterization of Cu11In9 crystal using first-principles density functional theory calculation

Abstract

First-principles calculations of the physical, mechanical, thermodynamic and electronic properties of monoclinic Cu11In9 crystal are performed together with their temperature, hydrostatic pressure and direction dependences. First of all, the optimized lattice constants and energy of formation of Cu11In9 single crystal are investigated, by which its hydrostatic pressure-dependent elastic constants are characterized. Next, based on the characterized angular character of atomic bonding, Zener factor and directional Young’s modulus, the hydrostatic pressure-dependent mechanical characteristics of the single crystal, such as ductile/brittle behavior and elastic anisotropy, are examined. Moreover, the polycrystalline elastic properties of Cu11In9, including bulk, shear and Young’s modulus, and its ductile/brittle and microhardness characteristics are assessed as a function of hydrostatic pressure. After that, quasi-harmonic Debye modeling is carried out to investigate the temperature-dependent Debye temperature and heat capacity of Cu11In9 single crystal. Finally, its electronic band structures and density of states profiles are characterized through electronic characteristic analysis. An extensive comparison of the present results with the literature published data of Cu11In9, CuIn and Cu2In is performed.The present calculations indicate that Cu11In9 crystal exhibits low elastic anisotropy, low hardness, high ductility, and good electrical conductance. Moreover, its heat capacity closely follows the Debye T3-law at temperatures below the Debye temperature, and attains the Dulong–Petit limit at temperatures far above the Debye temperature. In addition, the crystal comprises higher elastic isotropy, less ductility, greater Debye temperature and better electrical conductivity than CuIn and Cu2In. Besides, the bulk, shear and Young’s modulus, and microhardness of polycrystalline Cu11In9 are all larger than those of CuIn but smaller than those of Cu2In.