Thermodynamic, mechanical stabilities and thermoelectric behavior of the XVSi (X = Co, Rh) half-Heuslers

Abstract

Utilizing Boltzmann transport equations, structural, electronic, elastic, and thermoelectric properties, as well as thermodynamic stability of RhVSi and CoVSi half-Heusler compounds were investigated using the first-principle calculations in the framework of the density functional theory. The results of structural and elastic calculations and the thermodynamic phase diagrams indicate that these compounds are stable in the MgAgAs-type cubic structure with the F $$\overline{4}$$ 3m space group. The electronic structure was calculated using the Generalized Gradient Approximation with Tran–Blaha potential. It was found that both RhVSi and CoVSi are non-magnetic semiconductors with indirect gaps along X–W direction with values of 1.20 eV and 0.92 eV, respectively. High ZT values at 1000 K of 0.79 and 0.78 were obtained for RhVSi and CoVSi. The maximum value of the Seebeck coefficient (S) value for RhVSi and CoVSi is about $$244\,\frac{{\upmu {\text{V}}}}{{\text{K}}}$$ and $$226\,\frac{{\upmu {\text{V}}}}{{\text{K}}}$$ , respectively. The phonon dispersions reveal that the structures of these compounds are stable.