Optical properties of nanostructured sol-gel thin films doped with Fe₂O₃ and their ferromagnetic characterization by mössbauer spectroscopy

Sol-gel thin films containing Fe ₂O ₃ were deposited onto glass substrates by the dip-coating method at room temperature. Fe ₂O ₃ enriched with the isotope ⁵⁷Fe was embedded in two kinds of matrices: zinc oxide (ZnO) and silica (SiO ₂). X-ray diffraction (XRD) was used for morphology and structure determination of the nanostructures and showed that the ZnO exhibit a wurtzite form when the film is annealed at 450°C for 20 min. SiO ₂ thin films at C ₁₆H ₃₃PEO ₂₀:Fe ₂O ₃ = 1:2.7 × 10 ^-1 molar concentration exhibit a hexagonal nanophase produced by the diblock copolymer Brij58 (C ₁₆H ₃₃PEO ₂₀). Optical absorption and infrared spectroscopy techniques were used to evaluate the optical quality of the films. In order to determine if the Fe ₂O ₃ was incorporated into the matrices, room temperature Mössbauer spectra of both samples were obtained. In both cases the hematite spectrum was obtained, corroborating that the incorporation of the Fe ₂O ₃ to the matrices was done without chemical reaction whatsoever.