This work describes a preparation and characterization of nanoparticles of iron(III) oxide substituted with scandium embedded in silica matrix. The nanoparticles were prepared by the conventional sol–gel method yielding mostly β-Fe2O3 substituted with various amount of scandium(III) ions.
Mossbauer spectroscopy was carried out to determine the content of other iron oxides phases. System was characterized by magnetic measurements. Powder X–ray diffraction was used to verify the composition and to determine the lattice parameter and particle size.
β-Fe2O3 is formed at the temperatures of 1000 and 1100 °C at composition Fe2−xScxO3 for x ≥ 0.2 and at temperature 1100 °C for x = 0.1. After annealing at 900 °C, β-Fe2O3 is formed in the samples with x = 0.6. At temperatures higher than 1250 °C, β-Fe2O3 is transformed into hematite. This temperature is significantly higher than temperatures given in literature (600-700 °C) [1],[2].
Lattice parameter of β-Fe2O3 is linearly dependent on the scandium content and depends also on the annealing temperature. Particles size increases with increasing annealing temperature. Low temperature Mossbauer spectroscopy shows a dependence of the blocking temperature on the scandium concentration due to weakening of the exchange interactions by the substitution of iron by diamagnetic scandium ions.