Enhanced optoelectronic and thermoelectric properties of half Heusler compounds KXSb (X = Be, Mg, Ca and Sr): A first principle study

Abstract

In the present paper, structural, electronic, elastic, thermodynamic, optical, and thermoelectric properties of h-H alloys KXSb (X = Be, Mg, Ca, and Sr) are investigated for the first time. These properties were explored using quantum mechanical model – the density functional theory (DFT) with both GGA-PBE and TB-mBJ exchange-correlation functional. The Boltzmann transport equations and the Full Potential Linearized Augmented Plane wave (FP-LAPW) approach, as built into the WIEN2k code, are used to investigate these properties. The band structures and density of states (DOS) are also studied. The half-Heusler compounds show semiconductor properties with both the GGA and mBJ methods, while the KBeSb alloy exhibits metallic nature under the GGA-PBE approach. The elastic and thermo dynamical properties were also investigated, and the results revealed that the compounds are mechanically and thermally stable. The observed high Debye temperature (ϴD) implies that the alloy is harder and possesses a significant Debye sound velocity. The current paper highlights the optical and thermoelectric applications of the alloys. At 900 K, KCaSb exhibits maximum power factors of 8.83 × 1011 (W/mK2s) with the GGA-PBE method and 8.19 × 1011 (W/mK2s) with the TB-mBJ approach.