Superparamagnetic, High Magnetic α-Fe & α″-Fe₁₆N₂ Mixture Prepared from Inverse Suspension-Polymerized...

Oleic acid (OA)-modified Fe₃O₄ nanoparticles were successfully covered with polyanilines (PANIs) via inverse suspension polymerization in accordance with SEM and TEM micrographs. The obtained nanoparticles were able to develop into a ferrite (α-Fe) and α″-Fe₁₆N₂ mixture with a superparamagnetic property and high saturated magnetization (SM) of 245 emu g^-1 at 950 °C calcination under the protection of carbonization materials (calcined PANI) and other iron-compounds (α″-Fe₁₆N₂). The SM of the calcined iron-composites slightly decreases to 232 emu g^-1 after staying in the open air for 3 months. The calcined mixture composite can be ground into homogeneous powders without the segregation of the iron and carbon phases in the mortar without significantly losing magnetic activities.