Theoretical study of structural, electronic, phonon and thermoelectric properties of KScX (X=Sn and Pb) and KYX (X=Si and Ge) half-Heusler compounds with 8 valence electrons count

Structural, electronic, lattice dynamic and transport properties of cubic KScX (X = Sn and Pb) and KYX (X = Si and Ge) half-Heusler (HH) compounds with valence electrons count VEC = 8 have been investigated using first-principles calculations and Boltzmann transport theory. The band gaps between valence band and conduction band region are 0.48 eV, 0.50 eV, 0.25 eV and 0.27 eV for KScSn, KScPb, KYSi and KYGe respectively, suggest that these HH compounds show direct band gap semiconducting nature, in agreement with the previously reported results. The calculated phonon dispersion curves for these compounds show their stability in cubic MgAgAs phase. The thermoelectric properties are also calculated for these compounds and it is found that they have high power factor for p-type doping concentration. (C) 2019 Elsevier B.V. All rights reserved.