Exploring the structural, elastic, lattice dynamical stability and thermoelectric properties of semiconducting novel quaternary Heusler alloy LiScPdPb

Quaternary Heusler alloy LiScPdPb with an 18-valence electron count show incredible applications in photo-voltaic, spintronics, and thermoelectric materials. The study related to the structural, elastic, mechanical stability, and zone center phonon frequencies of LiScPdPb quaternary Heusler alloy is not investigated so far. Therefore, in the present article, the equiatomic quaternary Heusler alloy 'LiScPdPb' is studied in detail for their structural stability, elastic and mechanical stability. The research work presented in this report is undertaken by implementing first-principles Density Functional Theory (DFT). The non-magnetic character of the alloy is determined by the Slater-Pauling rule. Furthermore, density functional perturbation theory is implemented to calculate the phonon dispersion curves, phonon density of states, and zone center phonon frequencies of LiScPdPb. The calculated positive phonon frequencies have established the dynamical stability of LiScPdPb in the cubic phase. Raman and infrared phonon modes are also identified for the first time for LiScPdPb by implementing density functional perturbation theory. The calculated value of the bandgap is 0.22eV using generalized gradient approximations, while the bandgap of 1.62eV is observed by using Gaussian-Perdue-Burke-Ernzerhof (Gau-PBE) hybrid functional, which ensures the semiconducting nature of the alloy. In addition to the structural, elastic, mechanical, electronic, and lattice dynamical properties, the thermoelectric response of this alloy are also evaluated by including semi-classical Boltzmann transport theory. The maximum value of the obtained figure of merit for LiScPdPb is 0.18 at 1200 K, which opens up new avenues for its applications in electronic industries. Hence, the present work will provide a fertile field for the experimental researchers to synthesis this alloy for thermoelectric applications.