Electronic structure and properties of (Fe_1-xNi_x)₄N (0≤x≤1.0)

The electronic structure, magnetic moment, elastic and ductile properties of the nitride (Fe_1-xNi_x)₄N with x from 0.00 to 1.00 were investigated by first-principles calculations within generalized gradient approximation (GGA). The calculated results indicate that the substitution of Ni for Fe in the (Fe_1-xNi_x)₄N nitride leads to the shrinkage of the lattice parameters and the decrease of the stability of this nitride with increasing x value from 0.00 to 1.00. The alloying ability of Ni to the nitride decreases with Ni content. In comparison with N-Fe covalent bond, the N-Ni covalent bond is weaker and can be also strengthened with Ni content in the nitride. The interactions between Fe2 (at face-centered site) and Ni1 (at corner site) atoms, between Ni1 and Ni2 (at face-centered site) atoms are bonding effect. However, the interactions between Fe2 and Fe2 atoms, between Fe2 and Ni2 atoms, between Ni2 and Ni2 atoms are anti-bonding effect and their bonding strengths depend on the Ni content in the nitride. The magnetic moments (MM) of (Fe_1-xNi_x)₄N and Ni2 atom decrease with the increase of Ni content, and the MM change of Fe2 and Ni1 atoms is opposite to that of Ni2 atom. Generally, the substitution of Ni for Fe improves the elastic properties and reduces the ductility for the (Fe_1-xNi_x)₄N nitride.