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.