First-principles investigation of the elastic, thermodynamic, and thermoelectric properties of NaAlSn

In this study, the thermoelectric characteristics of the alloy NaAlSn (half-Heusler) were probed with the help of Density Functional Theory (DFT) coupled with the Boltzmann transport approach. The electrical characteristics and structure optimization calculations were conducted through the Quantum ESPRESSO code. The elastic and thermodynamic properties were calculated using the thermo_pw code. The phonon dispersion curve proves dynamical stability. A comprehensive study of the major thermoelectric parameters was conducted as a function of varying hole and electron concentrations using the BoltzTraP code. The calculated lattice parameter for NaAlSn is found to be 6.78[Formula: see text]Å, showing solid agreement with the available literature. The electronic band structure calculation shows that NaAlSn exhibits a direct bandgap (0.16[Formula: see text]eV) semiconducting behavior. The combination of a high Seebeck coefficient and relatively low electronic thermal conductivity results in a favorable thermoelectric performance, yielding peak ZT values of 1.45 (p-type) and 1.6 (n-type) at 600[Formula: see text]K. These results demonstrate that NaAlSn is a promising candidate for mid-temperature thermoelectric applications.