Influence of calcination temperature on gadolinium doped magnesium-zinc ferrite nanoparticles: Structural, optical, and photocatalytic properties for water splitting applications

Gadolinium doped Magnesium-zinc ferrite nanoparticles with the chemical formula Mg 0.5 Zn 0.5 Gd 0.1 Fe 1.9 O 4 , was synthesised in an environmentally friendly sol-gel route. As-prepared and samples calcined at 550°C, 850°C, and 1150°C were made ready for the present investigation. They adhered to a cubic spinel structure that was single-phase and devoid of a second-phase element, as evidenced by the Rietveld refinement analysis. XRD determined the crystallite size, which lies between 30.2 and 40.8 nanometres (nm). The crystallite size increases and, unit cell volume, dislocation density, and lattice strain are decreased with the increasing of calcination temperature. SEM surface activity shows that each particle is well-cemented and permits particle agglomeration. TG/DTA spectra showed a total weight loss percentage of 2.6 %, 1.73 %, 1.22 %, and 1.951 % for the as-prepared, 550°C, 850°C, and 1150°C, respectively. DSC thermal analysis method measures endothermic peaks below 100°C and exothermic peaks above 200°C. From FTIR, the octahedral and tetrahedral sites' metal-oxygen vibrations give rise to the ν 1 and ν 2 absorption bands from 487.99 cm −1 to 962.47 cm −1 . The observed UV–vis. absorption can be attributed to electron excitation from the O-2p level into the Fe-3d level, measured at 1.785 eV for as-prepared and observed decreasing trend from 1.948 to 1.904 eV, with calcination temperature. The Raman modes of the doped material exhibited minor frequency shifts from 200 to 1000 cm −1 , as revealed by Raman spectroscopy. Three peaks can be seen in the broad Raman line spectra for As-Prepared at 237 cm −1 , 645 cm −1 , 917 cm −1 , and for each of the following calcinations: 550°C at 315 cm −1 , 747 cm −1 ,861 cm −1 , 850°C at 237 cm −1 , 674 cm −1 , 945 cm −1 , and 1150°C at 284 cm −1 , 645 cm −1 , 875 cm −1 . These differences can be linked to variations in the cation distribution, and the peaks are located between 284 and 945 cm −1 . The prepared sample calcinated at 850°C exhibits superior photocatalytic and photoelectrochemical performance for water-splitting applications. • Gd 3+ ion doped Mg-Zn nanoparticles were synthesized by Sol-gel auto-combustion. • Analyse with XRD and SEM to confirm the nano sized particles with spinel ferrites. • DSC, TG-DTA studies were done to study thermal behaviour and weight loss. • UV-Vis and Raman spectroscopy analyses were performed to study optical properties. • Photocatalytic behaviour was studied for water-splitting applications.