Nitrogen ordering and ferromagnetic properties of ϵ-Fe3N1+x (0.10≤x≤0.39) and ϵ-Fe3(N0.80C0.20)1.38

Abstract The ϵ-phase iron nitrides ϵ-Fe 3 N 1+ x with x =0.10, 0.22, 0.30, 0.33, 0.39 and a carbonitride ϵ-Fe 3 (N 0.80 C 0.20 ) 1.38 were investigated by neutron diffraction. In these phases the non-metals occupy octahedral interstices in an hcp arrangement of Fe. Type and degree of occupational order of N and N+C, respectively were determined as a function of composition and temperature. The ordering of N is closely related to that of the ϵ-Fe 3 N ‘ideal’ structure (space group P6 3 22 ). Neutron diffraction data on ϵ-Fe 3 N 1.22 revealed lowered symmetry ( P312 ). An earlier proposed ϵ-Fe 2 N type ordering ( P31m ) was not observed for the iron nitride samples but it was found for ϵ-Fe 3 (N 0.80 C 0.20 ) 1.38 . Magnetisation data show that the nitride and carbonitride phases are soft ferromagnetic materials and confirmed magnetic structure data as derived from neutron diffraction.