MAGNETIC PARTICLES DERIVED FROM IRON NITRIDE

Due to its high saturation magnetization (σS(OK) ≃ 208 emu/g) and to the ease of obtaining it as a particulate material, Fe4N could be a suitable magnetic material for replacing highly reactive metallic iron pigments (σS(OK) ≃ 218 emu/g) in high density recording. Throughout a nitriding process of properly selected precursors Fe4N can be obtained in either one of two morphologies: acicular or isotropic. Further protection of the magnetic particles can be insured through coating of the precursor particles prior to thermal decomposition in NH3/H2 atmosphere or through substitutions with selected elements. The obtained passivated nitrides are characterized by high magnetic properties (HC ≃ 600 Oe; σS ≃ 105 emu/g) and chemical stability well adapted for using them as magnetic pigments for high density recording. © 1990 IEEE