Magnetic properties, hyperfine interactions and thermal stability of perovskite-type Fe-Ni nitrides Y-(Fe_1-xNi_x)₄N (0<x<0. 9)

Magnetic properties, hyperfinc interactions and thermal stability of the perovskite-type Fe-Ni nitrides γ′(Fe_1-xNi_x)₄N have been investigated by vibrating sample magnetometer, nuclear magnetic resonance and thermogravimeiric analysis combined with X-ray diffraction and Mössbaucr spectroscopy. The composition dependence of lattice parameter, saturation magnetization and Curie temperature has been found to decrease monotonically with increasing Ni concentration. This behavior contrasts with that of the corresponding (fcc) y-Fe_1-xN_x, alloys, for which each of these properties exhibits a maximum at some intermediate composition. The thermal decomposition temperature also decreases with x; the Fe-Ni nitrides, however, show a higher resistance against oxidation on heating the pure Fe nitride. Good agreement was observed between the hyperfinc fields, which are greatly influenced by Ni substitution, by NMR and by Mössbauer spcctroscopy.