Electronic structure, phonon stability, mechanical and high-temperature thermoelectric properties of Li-based quaternary Heusler alloys

Abstract

This paper presents a detailed discussion of thermoelectric and electronic properties of newly designed Li-based Heusler compounds (LiScPtGe, LiYPtSn, LiYPdPb) using Boltzmann transport theory alongside the first-principles calculations. Our investigations predict that these materials exhibit band gaps 0.76 eV (for LiScPtGe), 0.67 (for LiYPtGe) and 0.21 eV (for LiYPdPb), respectively. All the reported materials are indirect band gap semiconductors; mechanical and dynamical stability is also confirmed. At 300 K, the lowest value of lattice thermal conductivity is observed in LiYPdPb (21.64 Wm-1 K−1), which is very small as compared to the other two materials. The perceived value of the figure of merit (ZT) is 0.61 (for LiScPtGe), 0.52 (for LiYPtSn) and 0.35 (for LiYPdPb) respectively, and probably ensure a considerable thermoelectric efficiency of these newly designed materials.