Structural stability and site preference of Pr(Fe, M)12 and Pr(Fe, M)12Nx (M = Ti, V, Cr, Mo)

A systemic study of the structural properties of Pr(Fe, M)(12) and Pr(Fe, M)(12)N-x (M = Ti, V, Cr, Mo) compounds has been performed by a series of interatomic pair potentials obtained through the lattice inversion method. Adding a ternary element Ti, V, Cr or Mo makes the crystal cohesive energy of Pr(Fe, M)(12) decrease markedly, which indicates that Ti, V, Cr or Mo helps stabilize the crystal structure. The calculated preferentially occupation site of the stabilizing element M is found to be the 8i site. The interstitial N atoms only occupy 2b interstitial sites in Pr(Fe, M)(12). The calculated results correspond well to available experimental data. The method utilized in the present investigation provides an effective approach to predict different properties of Pr(Fe, M)(12) and Pr(Fe, M)(12)N-x.