Ultrasmall α-Fe₂O₃ Superparamagnetic Nanoparticles with High Magnetization Prepared by Template-Assisted Combustion Process

A template-assisted combustion-based method is developed to synthesize the ultrasmall (below 5 nm) α-Fe2O3 nanoparticles. The iron and ammonium nitrate are used as oxidizers, glycine as a “fuel” and mesoporous silica (SBA-15) as a template. Because of the ultralow sizes and high crystallinity, the combustion-derived α-Fe2O3 nanoparticles exhibit superparamagnetism in the temperature range of 70–300 K. The high specific surface area (132 m2/g) of α-Fe2O3 indicates the important role of surface magnetic spins resulting in remarkably high magnetization (21 emu/g) at 300 K.