Ab initio predictions of thermoelectric, mechanical, and phonon characteristics of FeTiSe half-Heusler compound

Abstract

In order to meet the increasing global energy demand, half-Heusler (H–H) alloys are found to be a cheap and efficient choice for energy generation applications. The electrical, structural, thermoelectric, dynamical, and mechanical properties of the novel FeTiSe half-Heusler alloy were predicted using the density functional theory (DFT). The equilibrium lattice constant was obtained as 5.62 Å. The electronic band-structure (B–S) and projected-density of states (P-DOS) were evaluated, and the band gap was obtained as 0.813 eV. Furthermore, applying the density functional perturbation theory (DFPT), we predicted the alloy's dynamical stability. Our findings from elastic constants revealed that the alloy is stiff, brittle, elastically anisotropic, and mechanically stable. For the n-type and p-type compositions, the Seebeck coefficients were found to be −273.53 and 190.13 μV/K at 1300 K, and figure of merit zT = 1.02 and 0.46 and zT = 2.92 and 2.8 at 300 and 1300 K, respectively. Thus, FeTiSe exhibits promising thermoelectric characteristics.