Structural stability, phase transition, and mechanical and electronic properties of transition metal nitrides MN (M = Tc, Re, Os, and Ir): First-principles calculations

The structural stabilities, phase transition, and mechanical and electronic properties of MN (M = Tc, Re, Os, and Ir) with different structures were reported by means of first-principles total energy calculations. The calculations indicate that the NbO-type structure is more energetically preferred for TcN and ReN, and the Pmn2 ₁-type structure is more favorable for IrN and OsN. The NbO-type ReN and TcN are stable up to 51.9 and 19.5 GPa, respectively, above which NiAs type structure becomes more energetically favorable. Both NiAs-type ReN and Pmn2 ₁-type OsN exhibit excellent mechanical properties due to the strong bonding between M and N atoms, similar to TiN. The electronic structure calculation suggests that the Pmn2 ₁-IrN is a semiconductor with an indirect band gap of about 0.38 eV, suggesting the potential technological applications.