First principles prediction of vanadium and niobium nitrides with M2N3 stoichiometry

The possible crystal structures of transition metal nitrides M2N3 (M = V or Nb) were investigated using first principles calculations. We predict that the ground state structures of V2N3 and Nb2N3 are trigonal and orthorhombic, respectively, over a wide pressure range. Examinations of the thermodynamic stabilities of trigonal V2N3 and orthorhombic Nb2N3 with respect to phase decomposition suggest that they can be prepared under moderate pressure conditions. Elastic constant calculations indicated that both nitrides were mechanically stable and are potential candidates for hard materials.