Exploration of Some Novel Semiconducting Half-Heuslers for Energy Applications

Half-Heusler (HH) compounds hold promise as a solution to the energy crisis due to their high- temperature thermoelectric properties. We explored the stability, electronic, phonon, mechanical, and thermoelectric properties of several novel 18-VEC hH, including XFeTe (X = Ti, Hf), XNiAs (X = Sc, Y), NbXBi (X = Ru, Os), XIrY (X = Nb, Ta; Y = Sn, Pb), and TaFeBi. We utilized Density functional theory and Semi-classical Boltzmann transport theory. The compounds are thermodynamically, dynamically, and mechanically stable. They are non-magnetic semiconductors, all with moderate band gaps below 1.00 eV. All studied compounds show better stiffness, hardness, elastic anisotropy, and high melting points, but only HfFeTe lacks ductility. The compounds containing much heavier elements like Bi or Pb exhibit κl lower than 11 Wm−1K−1 , whereas other compounds have higher. A large PF and low κl result in zT around 1 or higher, except for XNiAs, where flat bands deteriorate zT . The electrons show superior transport properties compared to holes for XFeTe and XNiAs, while reverse is true for others. Among the studied compounds, TiFeTe achieves highest zT of 1.79 at 1200 K for electrons. We observe that the doped hH compounds are promising for high-temperature power generation.