Electronic, elastic and thermal properties of hexagonal TM5Si3N investigated by first-principles calculations

During the current study, structural, electrical, elastic, and thermal properties of TM5Si3N (TM = V, Nb, and Ta) Nowotny phase were researched using first-principles calculations. The calculated formation enthalpies and phonon dispersion spectrums of these TM5Si3N Nowotny phases indicate that they are dynamically and thermodynamically stable. Because of the strong hybridization between TM-d state and Si-p and N-p states, TM5Si3N can form TM-Si and TM-N bonds. The obtained elastic anisotropy indexes, two-dimensional (2D) planar projection, and three-dimensional (3D) surface constructions demonstrate that the elastic modulus of TM5Si3N is anisotropic, and the order of elastic anisotropy is Ta5Si3N > Nb5Si3N > V5Si3N. In addition, the minimum thermal conductivity of TM5Si3N was calculated using the Clarke's and Cahill's models, which was found to be anisotropic and in the following order of Ta5Si3N > Nb5Si3N > V5Si3N.