Search Results (2)

ZnAlFe_1−xSm_xO₄ (x = 0, 0.02, 0.04, 0.06, 0.08) spinel ferrites were successfully obtained for the first time via a sol–gel autocombustion technique using citric acid as the combustion/chelating agent. These materials were then employed as photocatalysts for the degradation of Evans Blue, considered herein as a model organic pollutant. The XRD and FTIR analysis confirmed the achievement of pure spinel ferrite structures for all the materials. TEM analysis showed that the average particle sizes decline from about 27 for the undoped material to 17 nm for samarium-doped materials, and the magnetic characterization at room temperature indicated the paramagnetic conduct for the studied samples. All the photocatalysts were active in Evans Blue photodegradation. The best photocatalytic performances were observed for the ZnAlFe_0.94Sm_0.06O₄ formulation and explained by the smallest values calculated for lattice parameter, interplanar distance, and particle-size values. By adding H₂O₂ and applying the modelling and optimization of the photocatalytic process for the best material, the half-life of the pollutant decreased significantly from 115 min to about 7 min (about 16-times), and the colour-removal efficiency was almost 100%. Full article

Spinel cobalt ferrite/hexagonal strontium hexaferrite (2CoFe₂O₄/SrFe_12−2xSm_xLa_xO₁₉; x = 0.2, 0.5, 1.0, 1.5) nanocomposites were fabricated using the tartaric acid precursor pathway, and the effects of La³⁺–Sm³⁺ double substitution on the formation, structure, and magnetic properties of CoFe₂O₄/SrFe_12−2xSm_xLa_xO₁₉ nanocomposite at different annealing temperatures were assayed through X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometry. A pure 2CoFe₂O₄/SrFe₁₂O₁₉ nanocomposite was obtained from the tartrate precursor complex annealed at 1100 °C for 2 h. The substitution of Fe³⁺ ion by Sm³–⁺La³⁺ions promoted the formation of pure 2CoFe₂O₄/SrFe₁₂O₁₉ nanocomposite at 1100 °C. The positions and intensities of the strongest peaks of hexagonal ferrite changed after Sm³⁺–La³⁺ substitution at ≤1100 °C. In addition, samples with an Sm³⁺–La³⁺ ratio of ≥1.0 annealed at 1200 °C for 2 h showed diffraction peaks for lanthanum cobalt oxide (La₃Co₃O₈; dominant phase) and samarium ferrite (SmFeO₃). The crystallite size range at all constituent phases was in the nanocrystalline range, from 39.4 nm to 122.4 nm. The average crystallite size of SrFe₁₂O₁₉ phase increased with the number of Sm³⁺–La³⁺ substitutions, whereas that of CoFe₂O₄ phase decreased with an x of up to 0.5. La–Sm co-doped ion substitution increased the saturation magnetization (Ms) value and the subrogated ratio to 0.2, and the Ms value decreased with the increasing number of double substitutions. A high saturation magnetization value (Ms = 69.6 emu/g) was obtained using a La³⁺–Sm³⁺ co-doped ratio of 0.2 at 1200 for 2 h, and a high coercive force value (Hc = 1192.0 Oe) was acquired using the same ratio at 1000 °C. Full article