Identification of ferric oxide polymorphs in nanoparticles prepared by sol-gel method and maximization of ε-Fe2O3 content

The effects of annealing temperature and Fe₂O₃ mass fraction in the initial mixture on the composition of ferric oxide polymorphs within the Fe₂O₃/SiO₂ nanocomposite prepared by sol-gel method were investigated. The structural and magnetic properties were characterized in detail by combination of XRD, high-resolution TEM, magnetic measurements and Mössbauer spectroscopy. The ∼91% of the ε-phase was reached with the characteristic particle diameter of 25 nm. It was observed that with increasing Fe₂O₃ mass fraction, the optimal annealing temperature decreases, while the width of the particle size distribution increases.