Synthesis of Ferric Oxide Nanoparticles with Controllable Crystal Phases by Salt-assisted Combustion Method

The salt-assisted combustion method was applied in synthesis of Fe2O3 nanoparticles by using Fe(NO3)3·9H2O, polyethylene glycol (PEG2000) and KCl as oxidant, fuel and salt, respectively. The products were characterized by HRTEM, XRD, LRS and N2 adsorption. It is found that the crystal phase (including α-Fe2O3, γ-Fe2O3 and the mixed phases of α-Fe2O3 and γ-Fe2O3) of Fe2O3 nanoparticles can be adjusted by changing the KCl/NO3- molar ratio. Addition of soluble inert KCl in the redox mixture solution for combustion synthesis results in the formation of well-dispersed γ-Fe2O3 nanoparticles and a drastic increase in the specific surface area from 21.96 to 102.35 m2/g. A mechanism was proposed to illustrate the possible formation process of different crystal phase nanoparticles with different character.