Electronic structure, mechanical, dynamical and thermoelectric properties of osmium-based half-Heusler alloys: A first-principles concept

Heusler alloys have attracted much attention due to their unusual physical properties for potential device applications. Here, we study osmium-based half-Heusler alloys OsYSb (Y = Ta, Nb, V) by density functional theory (DFT) simulations code. We show the semiconductor nature of these alloys based on computed band gaps with and without spin-orbit coupling (SOC), as confirmed by both the band structure, PDOS and DOS, which is necessary for thermoelectric (TE) calculations. Due to the flat valence bands of these alloys close to the Fermi level, the Seebeck coefficient of the p(n)-type at 300 K are 385.71 (288.10), 584.00 (460.00), and 1066.67 (940.74) $\mu \textrm {V} \cdot \textrm {K}^{-1}$ , for OsVSb, OsNbSb, and OsTaSb alloys, respectively. Furthermore, the high OsYSb alloys’ power factor and Seebeck coefficient in the n- and p-types suggest they might be a potential candidate for power generators. We also show these alloys’ chemical, dynamic and thermal stability, as confirmed by the absence of imaginary modes in the phonon dispersion curves and the negative formation energies.