The effect of dopped Al3+-Gd3+- Cr3+ on the chemical structure of M-type strontium hexaferrite and investigation on their photocatalysis properties

Abstract M-type strontium hexaferrite and substituted derivatives were synthesized via sol-gel auto combustion method with the formula of SrGdx Alx Crx Fe(12-3x) O19 ((x=0, 0.2, 0.4, 0.6, 0.8)(B0, B1, B2, B3, B4)). The findings of the Fourier-transform infrared spectroscopy (FTIR) spectrum revealed that characteristic peaks between 400 and 560 cm-1 were related to Fe-O bonds at octahedral and tetrahedral sites confirmed the hexaferrite bonding. Moreover, the X-ray diffractometer (XRD) represented that magnetoplumbite hexagonal structure had formed with little impurities. The crystallite sizes of the synthesized nanoparticles (NPs) were also around 42.6-75.4 nm and there is an increase in a lattice parameter from 5.79 to 5.87. The surfaces of the prepared samples were subsequently analyzed through field emission scanning electron microscopy (FESEM) surface images and micrographs illuminated the prepared ferrites have hexagonal structures and EDX spectra represent that all elements are belonging to the prepared composition. Hysteresis loops of SrGdx Alx Crx Fe(12-3x)O19 ((x=0, 0.2, 0.4, 0.6, 0.8)(B0, B1, B2, B3, B4)) depicted that Ms had decreased in a dramatic manner (from 68.36 to 27.66) as the number of dopants had increased (from 0.0 to 0.8).The c/a confirmed the formation of the hexaferrite. Also, the photocatalysis capability of prepared samples was studied under Visible light and the results declare that Sr Fe12O19 without any dopant shown 60% degradation while SrGd0.8 Al0.8 Cr0.8Fe11.2 O19 has shown the best ability under visible light with a 90% degradation rate. By contrast, SrGd0.8 Al0.8 Cr0.8 Fe11.2 O19 represented the highest photodegradation even after 3 times of recycling.