Mössbauer study of the (Fe1−xNix)4N compounds (0≤x≤0.6)

Abstract

Single phase γ′-Fe4N type (Fe1−xNix)4N compounds (0≤x≤0.6) have been synthesized by heating iron-nickel oxalates under a mixture stream of NH3 and H2. The compounds were investigated by x-ray diffraction and Mössbauer spectroscopy. The results confirm that the lattice constants decrease with increasing content of nickel. Compared with the same compositional Fe1−xNix alloys, the average expansion of the unit cell (δV/V) is 16.7% for γ-Fe-Ni alloys. The Mössbauer study shows that the substitution of nickel atoms for iron atoms has a tendency to locate at the corner sites. When x=0.5, all of the corner sites are completely occupied by nickel atoms.