Magnetic particles derived from iron nitride

Due to its high saturation magnetization ( sigma /sub s/(0K) approximately=208 emu/g) and to the ease of obtaining it as a particulate material, Fe/sub 4/N could be a suitable magnetic material for replacing highly reactive metallic iron pigments ( sigma /sub s/(0K) approximately=218 emu/g) in high-density recording. Throughout a nitriding process of properly selected precursors Fe/sub 4/N can be obtained in either of two morphologies: acicular or isotropic. Further protection of the magnetic particles can be ensured through coating of the precursor particles prior to thermal decomposition in NH/sub 3//H/sub 2/ atmosphere or through substitutions with selected elements. The obtained passivated nitrides are characterized by high magnetic properties (H/sub c/ approximately=600 Oe; sigma /sub s/ approximately=150 emu/g) and chemical stability well adapted for use as magnetic pigments for high-density recording.<
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