First-principles calculations on the electronic structure and thermoelectric properties of quaternary Heusler compounds: LiScPtSi and LiScPdGe

Abstract

This research work explores the two quaternary Heusler compounds within the 18-valence electron formalism i.e. LiScPtSi and LiScPdGe as the capable thermoelectric materials in the temperature range of 1200 K. The band structure of these compounds reports the indirect bandgap of 1.08 eV for LiScPtSi and 0.5352 eV for LiScPdGe, also declares as p-type semiconductors. This report presents the structural, electronic, phonon, elastic and mechanical properties for the practical utilization of the materials. The melting point of LiScPtSi and LiScPdGe are calculated as 1561 ± 300 K and 1245 ± 300 K respectively; owing to this fact all the prime thermoelectric properties along with the Figure of Merit (ZT) are calculated in the temperature range of 1200 K. The investigated materials are purely anisotropic with ductile property (can be stretched as wires), dynamically and mechanically stable. In an overview of thermoelectric properties, the Seebeck coefficient and the lattice thermal conductivity at 300 K for LiScPtSi are 1784 μV/K, 39.6 W/mK and for LiScPdGe are 894μV/K, 27.7 W/mK respectively. Nevertheless, the respective maximum Figure of Merit (ZT) is 0.57 and 0.53 at the 1200 K that ensures the materials to be efficient thermoelectric elements in the high-temperature range with reliable material properties. As the materials are first time investigated here in the detailed prospectus; the proposed research work is proficient to be considered in experimental research as well as for energy conversion applications.