Structural, optoelectronic, thermodynamic, and thermoelectric properties of LiScNiZ (Z = Si, Ge, Sn) quaternary Heusler compounds via DFT approach

Abstract

The novel quaternary Heusler alloys LiScNiZ (Z = Si, Ge, Sn) in the Y-type ordered structure have been reported in recent literature as stable and potentially synthesizable experimentally. However, to unveil their potential for advanced technological applications, comprehensive investigations of their physical properties are needed. Therefore, in this study, we investigate the structural, electronic, elastic, optical, thermoelectric, and thermal properties of LiScNiZ (Z = Si, Ge, Sn) alloys using density functional theory. The GGA-PBE and the TB-mBJ approximations have been adopted to signalize the exchange-correlation potential as generated by the Wien2k software. The electronic properties indicate that all compounds have a semiconducting behavior. The elastic parameters demonstrate that these alloys have been found to be mechanically stable as per the Born stability conditions and brittleness characteristics. The optical absorption range, from the visible to the ultraviolet spectrum, demonstrates these alloys' exceptional potential for optoelectronic technologies. Moreover, the thermodynamic characteristics have also been analyzed across a defined temperature and pressure regime, employing the quasi-harmonic Debye model imposed in the Gibbs2 framework. Finally, all critical thermoelectric features have been systematically investigated using the semi-local Boltzmann transport theoretical approach. The results demonstrate that at 300 K, the figure of merit reaches its highest value.