Preparation and characterization of sputtered Fe1−xNx films

Iron nitride films have been prepared by reactive DC magnetron sputtering. The composition of Fe1−xNx was varied over a range of 0 ≤ x ≤ 0.5 by controlling the nitrogen flow rate during sputtering. These films were characterized using powder X-ray diffraction (XRD), thermogravimetric and electron microprobe analysis. We found that the nitrogen content in the films increased with nitrogen gas partial pressure. XRD experiments revealed an evolution through the α-Fe, γ′-Fe4N, ɛ-Fe2 + zN, ζ-Fe2N, γ‴-FeN and γʺ-FeN phases, when the nitrogen gas mole percentage was increased from 0% up to 70%. Above 70%, only the γʺ-FeN phase was formed despite a measurable increase in the nitrogen content of the film with nitrogen gas partial pressure. Rietveld analysis of powder X-ray diffraction patterns revealed that this behavior is due to an increase in the nitrogen site occupation factor within the lattice.