Iron Nitride Nanopowders Prepared by High-Pressure Gas-Solid Reaction.

Fe₄N nanopowders were prepared using specially-made high-pressure gas-solid reaction equipment, and their composition, morphology, and magnetic properties were analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM). An average particle size of 35 nm was obtained at 0.4 MPa, an ammonia-to-hydrogen ratio of 3:1, 623 K, in an ammonia solution for 2 h. The hysteresis loop displayed a thin and narrow shape at 673 K during VSM tests. The saturation magnetization () reached 169.80 emu/g.