Gas phase preparation of spherical core–shell α′′-Fe16N2/SiO2 magnetic nanoparticles

Well-dispersed spherical core–shell α′′-Fe16N2/SiO2 ferro-magnetic nanoparticles were successfully synthesized from core–shell α-Fe/SiO2 nanoparticles. Introduction of oxidation prior to the nitridation process gives 90% of α′′-Fe16N2 phase contained in the core while no phase change is observed without oxidation. Saturation magnetization and coercivity are 148 emu g−1 and 1.82 kOe, respectively.