Structural, Electronic, Elastic and Thermal Properties of Li2AgSb: First-Principles Calculations

Based on the first-principles density functional theory calculations combined with the quasi-harmonic Debye model, the pressure dependencies of the structural, elastic, electronic and thermal properties of Li2AgSb were systematically investigated. The calculated lattice parameters and unit cell volume of Li2AgSb at the ground state were in good agreement with the available experimental data. The obtained elastic constants, the bulk modulus and the shear modulus revealed that Li2AgSb is mechanically stable and behaves in a ductile manner under the applied pressure. The elasticity-relevant properties, the Young's modulus and the Poisson's ratio showed that pressure can enhance the stiffness of Li2AgSb and that Li2AgSb is mechanically stable up to 20 GPa. The characteristics of the band structure and the partial density of states of Li2AgSb were analysed, showing that Li2AgSb is a semiconductor with a direct band gap of 217 meV at 0 GPa and that the increasing pressure can make the band structure of Li2AgSb become an indirect one. Studies have shown that, unlike temperature, pressure has little effect on the heat capacity and the thermal expansion coefficient of Li2AgSb.