Fe–N gradient films and epitaxial Fe16N2 single-crystal films

Abstract

Fe–N gradient films and epitaxial Fe16N2 single-crystal films were prepared with a facing-target sputtering system. The Rutherford backscattering spectrum, x-ray diffraction, and selected area electron diffraction indicate that the gradient films possess some composition and structure gradient. The α′′-Fe16N2, γ-Fe4N, ε-FexN(2<x⩽3), and ζ−Fe2N phases are present in the gradient films at different depths. The α′′-Fe16N2 single-crystal films correspond to a deformed body-centered tetragonal structure with parameters of a=b=5.72 Å and c=6.29 Å. They grew epitaxially on a NaCl(100) substrate with an orientation relationship of α′′-Fe16N2(001)∥NaCl(001) and α′′-Fe16N2[100]∥NaCl[100]. Perfect electron diffraction patterns with perfect symmetry in the [1̄11], [011], and [001] directions can be observed distinctly by a rotational double tilting sample stand. By controlling N2 partial pressure, substrate temperature, and crystal orientation, α′′-Fe16N2 single-crystal films can be successfully grown epitaxially.

A review of high magnetic moment thin films for microscale and nanotechnology applications

“…Probably the most comprehensive review on the FeN system, summarising theoretical understanding as well as experimental results up to 1999, is given by Coey and Smith 288 and is critical towards the "giant" Fe moment claim. Despite certain progress in getting closer to MBE-quality with plasmasputtering technology [see, for instance, Tian et al 289 for growth on NaCl (1 0 0) substrates, Kappaganthu and Sun 290 for growth on Si (1 0 0) wafers, and Ji et al 291 for growth on Fe-seeded GaAs (0 0 1) wafers reminiscent of the "golden" MBE recipe by Takahashi and coworkers] no high-moment single-crystal a 00 Fe 16 N 2 was stabilised and reliable reproducibility is still an issue. One explanation why the giant moment sometimes occurs and sometimes not is based on the degradation of the compound, i.e., a decomposition of the a 00 Fe 16 N 2 into the lower-moment a 0 Fe 8 N phase.…”

Fabrication and characterization of austenitic stainless steel : nitrogen films

“…With such a high nitrogen content in the gas, complete ordering of the nitrogen atoms in the film to form a"-FelbN2 was difficult, but the thermal energy at room temperature was not sufficient to form other nitride compound phases. For obtaining stronger peaks of a"-Fe16Nz, substrate heating during deposition was Films prepared at a working pressure of 30 mTorr could not yield a"-Fel& [114], as the nitrogen activity (even for % Nz in sputtering gas mixture as high as 10)…”