Chemical environment of iron atoms in iron oxynitride films synthesized by reactive magnetron sputtering

 An iron oxynitride film was deposited on silicon and glass substrates by magnetron sputtering in an Ar–N2–O2 reactive mixture. Rutherford back-scattering spectrometry was used to determine the film composition (Fe1.06O0.35N0.65). X-ray diffraction revealed the formation of a face-centred cubic (fcc) structure with a lattice parameter close to that of γ‴-FeN. X-ray photoelectron spectroscopy showed the occurrence of Fe–N and Fe–O bonds in the film. The local environment of iron atoms studied by 57Fe Mössbauer spectrometry at both 300 and 77 K gives clear evidence that the Fe1.06O0.35N0.65 is not a mixture of iron oxide and iron nitride phases. Despite a small amount of an iron nitride phase, the main sample consists of an iron oxynitride phase with an NaCl-type structure where oxygen atoms partially substitute for nitrogen atoms, thus indicating the formation of a iron oxynitride with an fcc structure.