Phase Stability,Magnetic And Electronic Properties Of Fe-N Compounds:First-principles Calculations

Transition metal nitrides are known to be outstanding chemical stability and corrosion resistance properties,which are easy to form semiconductor materials.The study about iron nitride materials is one of hot topics in the field of materials science,physics and other research fields,attribute to their high magnetic recording densities.Therefore,Fe-N compounds have always been favored by researchers.The stability,phase transition,magnetism and electronic properties of five different iron mononitride?FeN?phases are systematically studied using first-principles calculation based on density functional theory.The results show that ZnS-FeN structure is the most stable phase at the equilibrium lattice,which turns into NiAs-,Wurtzite-,NaCl-and CsCl-FeN at 19.70,20.63,53.55 and 123.77 GPa,respectively.Our magnetic analysis demonstrates that the ZnS,CsCl and Wurtzite structures are nonmagnetic,while the high-pressure NaCl and Ni As phases are magnetic,holding 2.27?_Band 1.61?_Bper Fe atom,respectively.The magnetic moments increase with the increasing of the volume for all considered structures according to analyzing the magnetovolume effect.In addition,the mechanical,magnetic and electrical properties with four various components of iron nitride are also discussed.The calculated elastic constants indicate that the FeN and?'-Fe₄N phases are significantly anisotropic,the?-Fe₂N exhibits some anisotropy to a certain degree.While the?-Fe₃N shows a relatively strong isotropic character.The ratios of bulk modulus?B?to shear modulus?G?,3.52for FeN,2.70 for?-Fe₂N,2.31 for?-Fe₃N and 3.58 for?'-Fe₄N,reveal their ductile nature.Magnetism calculations show that the ZnS structure is nonmagnetic,while the?-Fe₂N,?-Fe₃N and?'-Fe₄N phases are magnetic,the magnetic moment is respectively 1.47,2.04 and 2.49?_Bper Fe atom at the equilibrium lattice.From the change of the magnetic moment of the system,one can see that it increases with the N atom composition decreases.By the analysis of the density of states,the strength of p-d hybridization may be the main reason that affects the value of the magnetic moment.