Structural, mechanical, electronic, and thermoelectric properties of new semiconducting d0 quaternary Heusler compounds CaKNaZ (Z =Si, Ge, Sn). A density functional theory study

Abstract

Due to the increasing demand for energy, the development of new and good thermoelectric (TE) materials is very vital. In this study, with ab initio calculations, based on the density functional theory (DFT) using the self-consistent full potential linearized augmented plane wave (FPLAPW) method were performed to explore the structural, mechanical, electronic and thermoelectric properties of quaternary alloys CaKNaZ (Z = Si, Ge, Sn) with quaternary Heusler structure. optimization confirmed the most stable structure for CaKNaZ (Z = Si, Ge, Sn) compounds is Y1-type in the non-magnetic phase. All of the compounds have been shown to behave like semiconductors, with indirect band gaps of 0.82 and 0.69 for CaKNaSi, CaKNaSn respectively, and direct band gap of 0.46 for CaKNaGe. The theoretical study of thermoelectric properties for CaKNaZ (Z = Si, Ge, Sn) was carried out by Boltzmann theory as implemented in BoltzTraP code. we have obtained a high of figure of merit at moderate temperatures. This indicates that the studied alloys can be used in thermoelectric applications.