Magnetic properties of perovskite-type Fe-Ni nitrides γ′-(Fe1-xNix)4N (0≤x≤0.9)

In this work, we have succeeded in preparing gamma'-(Fe1-xNix)(4)N powder samples for x up to 0.9 and have undertaken a systematic study of their structural and magnetic properties by x-ray diffraction and vibrating sample magnetometry. The lattice parameters of the nitrides decrease monotonically from 0.3795 to 0.3747 nm with increasing Ni concentration. The saturation magnetization, measured at room temperature and liquid nitrogen, was found to decrease with increasing Ni concentration. The Curie temperature T-C also decrease with increasing Ni concentration, as well as with decreasing lattice parameter. Our results show that the lattice parameters, sigma(s) and T-C behave in contrast with those of the corresponding fcc gamma-Fe1-xNix alloys, for which each of these properties exhibits a maximum at some intermediate composition. (C) 1999 American Institute of Physics. [S0021-8979(99)20808-0].