Structural, electronic, elastic, thermodynamical and thermoelectric properties of TMN (TM = Co, Ni)

We have analyzed the structural, electronic, elastic, thermodynamical and thermoelectric (TE) properties of TMN (TM = Co, Ni) by using density functional theory (DFT) based on the generalized gradient approximation and semi-classical Boltzmann transport theory. The present TMN are found stable in the zinc blende structure with nonmagnetic configuration and have shown metallic behavior. Based on the analysis of the elastic constants and their derived parameters, these compounds are predicted to be ductile behavior, mechanically and thermodynamically stable. The effect of temperature on thermodynamical parameters such as lattice parameter, specific heat (C _v), entropy and thermal expansion coefficient (α) has been studied using quasi-harmonic approximation (QHA) in the range of temperature 0–800 K. The obtained results from QHA show that the TMN maintains their mechanical stability under temperature. The TE properties such as Seebeck coefficient, electrical conductivity, electronic thermal conductivity, power factor and figure of merit are calculated. It is found that these properties decreased with an increase in temperature, and at the temperature of 300 K, the TMN exhibits a high Seebeck coefficient, electrical conductivity and power factor. The calculated values of the figure of merit are 0.75 and 0.797 for CoN and NiN at 300K, respectively, making them promising materials for thermoelectric applications. (paper)