Influence of different ratios of Fe and N on the structural, mechanical, electronic properties of Fe_xN_ycompounds: First-principles study

The influences of different ratios of Fe and N on the structure, mechanical and electronic properties of FexNy compounds were studied by using the first-principles study. Our obtained lattice parameters are in excellent agreement with the experimental data. The calculated density of the FexN1 compounds increases with the Fe content, which is almost consistent with the trend of the experimental results. The elastic constants indicate that the FexNy compounds are mechanically stable. The values of B/G and Poisson's ratio indicate that the FexNy compounds exhibit ductile manner. As Fe content increases, B/G and Poisson's ratios decrease monotonically. In particular, Fe4N1 has the highest hardness among all the considered FexNy compounds. The obtained density of states shows that FexNy is metallic in nature. The peak of the state density becomes sharper with the increase of N content, indicating that the localization of these alloys is enhanced. Among the FexNy compounds, Fe1N1 has been found to be the most stable with respect to the band filling theory calculation.