Synthesis and characterization of Fe16N2 in bulk form
Abstract
Using molecular beam epitaxy and ion implantation, Japanese workers have formed Fe16N2 in thin Fe films. They report a large magnetic induction for this nitride, ≥2.8 T. In the present study, Fe16N2 has been prepared in bulk form by treating Fe powder with NH3/H2 gas mixtures at temperatures in the range 660-670 °C. The γ phase alloy, which forms under these conditions, was quenched to room temperature to form the α'-Fe-N phase and then heat treated at 120-150 °C to form the α`-Fe-N phase. The α' phase has been prepared in 80% purity, the other phase being nonmagnetic γ-Fe-N. The α` phase has been prepared in 50% purity, the impurity phases being α-Fe and γ-Fe-N. Magnetic measurements give saturation magnetizations at room temperature of 250±10 emu/g (2.6μB/Fe) for the α' phase, 285±10 emu/g (2.9μB/Fe) for the α` phase, and essentially zero for the γ phase. Mössbauer measurements confirm that nitrogen austenite is nonmagnetic. The anisotropy of Fe16N2 is small but detectable.
- Publication:
-
Journal of Applied Physics
- Pub Date:
- May 1994
- DOI:
- 10.1063/1.356925
- Bibcode:
- 1994JAP....75.6574H