Structural, Optical and Magnetic Properties of $$\alpha $$ α - $${\text {Fe}}_{2}{\text {O}}_{3}$$ Fe 2 O 3 - $${\text {SiO}}_{2}$$ SiO 2 and $${\text {Dy}}_{2}{\text {O}}_{3}$$ Dy 2 O 3 - $${\text {SiO}}_{2}$$ SiO 2 Composites Produced by a Facile Method

We prepared \({\text {SiO}}_{2}\), \({\text {Fe}}_{2}{\text {O}}_{3}\)-\({\text {SiO}}_{2}\), and \({\text {Dy}}_{2}{\text {O}}_{3}\)-\({\text {SiO}}_{2}\) composites by an enhanced method and reported the result of their structural, optical and magnetic properties. In the x-ray diffraction results of the \({\text {Fe}}_{2}{\text {O}}_{3}\)-\({\text {SiO}}_{2}\), \({\text {Fe}}_{2}{\text {O}}_{3}\) and the \({\text {SiO}}_{2}\) it is evident that these composites are crystallized in rhombohedral and trigonal structures, respectively. In the\({\text {Dy}}_{2}{\text {O}}_{3}\)-\({\text {SiO}}_{2}\) composite, \({\text {SiO}}_{2}\) transforms into a trigonal structure with the addition of Dy. The absorption bands belong to \({\text {Fe}}_{2}{\text {O}}_{3}\), and \({\text {Dy}}_{2}{\text {O}}_{3}\) were obtained using the Fourier transform infrared spectra. In ultraviolet–visible spectra, the photocatalytic properties of \({\text {Fe}}_{2}{\text {O}}_{3}\)-\({\text {SiO}}_{2}\) and \({\text {Dy}}_{2}{\text {O}}_{3}\)-\({\text {SiO}}_{2}\) were determined as a function of time at room temperature. Maximum transmittance change at 800 nm was 75% and 40% for composites \({\text {Fe}}_{2}{\text {O}}_{3}\)-\({\text {SiO}}_{2}\), and \({\text {Dy}}_{2}{\text {O}}_{3}\)-\({\text {SiO}}_{2}\), respectively. The photocatalytic property of \({\text {Dy}}_{2}{\text {O}}_{3}\)-\({\text {SiO}}_{2}\) composite increases gradually from short to long in the wavelength region where it exhibits a maximum value in the visible region. In magnetic measurements, a weak ferromagnetic behavior was observed in the \({\text {Fe}}_{2}{\text {O}}_{3}\)-\({\text {SiO}}_{2}\), while \({\text {Dy}}_{2}{\text {O}}_{3}\)-\({\text {SiO}}_{2}\) exhibited paramagnetic behavior as expected. The saturation and coercivity values for \({\text {Fe}}_{2}{\text {O}}_{3}\)-\({\text {SiO}}_{2}\) were found to be 0.15 \(\hbox {Am}^2\hbox {kg}^{-1}\) and 40 mT, respectively.