Structural stability and electronic properties of Co2N, Rh2N and Ir2N

The structural stability and electronic properties of Co2N, Rh2N and Ir2N were studied by using the first principles based on the density functional theory. Two structures were considered for each nitride, orthorhombic Pnnm phase and cubic Pa3¯ phase. The results show that they are all mechanically stable. Co2N in both phases are thermodynamically stable due to the negative formation energy, while the remaining two compounds are thermodynamically unstable. The calculated properties show that they are all metallic and non-magnetic. Ir2N at Pnnm phase is a potentially hard material. The bonding behavior is analyzed.