A Density Functional Theory Evaluation for the Feasibility of the Li-Based Os-Family Quaternary Heusler Compounds LiNbOsX (X = Si, Ge, Sn) for Thermoelectric Devices

Abstract The present study reports the structural stability, electronic features, mechanical robustness and thermoelectric performance of three newly identified 18-valence electron count follower Li-based quaternary Huesler compounds LiNbOsSi, LiNbOsGe, and LiNbOsSn in a unified framework. All properties are computed and examined within the framework of density functional theory and the Boltzmann transport equations. The calculated melting points of all three alloys LiNbOsSi, LiNbOsGe, and LiNbOsSn are found to be 2105 ± 300, 2008 ± 300, and 1904 ± 300 K, respectively. These Os based Li Hueslers compounds have high thermoelectric potential with significant Seebeck coefficient and a favorable figure of merit. The semiconducting nature of all three alloys has been confirmed from the calculated indirect gaps, i.e. 0.0998, 0.248, and 0.32 eV. The structural and electronic properties are discussed along with the particular atomic contribution by the density of states. This study establishes the dynamic and thermodynamic stability of LiNbOsX (X = Si, Ge, Sn) compounds. Therefore, the present study suggests that these LiNbOsX compounds possess the necessary mechanical stability, electronic structure, and thermoelectric efficiency to serve as promising candidates for high-temperature thermoelectric modules.