Thermoelectric Performance of XXYIn (X = Fe, Ru; Y = Nb, V) Heusler Alloys: A DFT Study

Density functional theory (DFT)–based calculations are performed to investigate structural, electronic, and thermoelectric properties of XXYIn (X = Fe, Ru; Y = Nb, V) full and quaternary Heusler alloys using Quantum ESPRESSO package. We have calculated transport properties using semi-classical Boltzmann theory with constant relaxation time and n-type charge carrier concentrations 10 21 and 10 22 cm −3 . First, we investigate the stability of alloys by computing their mechanical and elastic properties, which indicate that all alloys are mechanically stable. To compute lattice thermal conductivity, we have used Callaway’s model. We find that Ru 2 VIn has lowest value of thermal conductivity compared to other compounds. FeRuNbIn has a maximum value of Seebeck coefficient ( S ) at around 400 K and carrier concentration 10 21 cm −3 , while Fe 2 NbIn and Fe 2 VIn have the largest values of S at the other concentrations, respectively. Ru 2 NbIn has the largest value of power factor at 1300 K in 10 22 cm −3 . Largest values of figure of merit ( ZT ) are 0.11 at 600 K for 10 21 cm −3 concentration and 0.22 at 1300 K for 10 22 cm −3 concentration for FeRuNbIn alloy.