Explorations of electronic, elastic and thermal properties of tetragonal TM4N3 (TM=V, Nb and Ta) nitrides

Abstract

In this work, we performed the first-principles calculations to reveal the electronic, elastic and thermal properties of the tetragonal TM4N3 (TMV, Nb, Ta) nitrides. The obtained electronic structures indicated that there is the p-d hybridization between N and TM atoms, and the electrons transfer from TM to N atoms to form TMN bonds. The polycrystalline elastic modulus was obtained from the single-crystal elastic constant. Based on the elastic constants and moduli, the elastic anisotropy was discussed by elastic anisotropy indexes and three-dimensional (3D) surface construction and its projection. Besides, Debye temperature, sound velocity and minimum thermal conductivity were also analyzed. The results showed that these nitrides are mechanically stable and ductile. Meanwhile, the elastic and thermal properties of the tetragonal TM4N3 (TMV, Nb, Ta) nitrides are anisotropic, and the order of anisotropy in elastic modulus and minimum thermal conductivity for TM4N3 (TMV, Nb and Ta) nitrides is V4N3 > Nb4N3 > Ta4N3.