Strong-base free synthesis enhancing the structural, magnetic and optical properties of Mn/Co and Zn/Co substituted cobalt ferrites

In recent years, the strong-base free synthesis has attracted much interest due to their numerous advantages as being eco-friendly techniques. Herein, we successfully synthesized spinel cobalt ferrites, with compositions MxCo1−xFe2O4 (x = 0.0, 0.1, 0.3 and 0.5) where M is a transition metal ion as Mn2+ and Zn2+, by a novel strong-base free approach, enabling minimization of hazardous products. The single phase has obtained by annealing the created precursors at relatively low temperature 1000 °C for 2 h. The average crystallite size was found to increase initially with increasing x = 0.3 and then decreased. Pyramidal-like structure has been displayed for the spinel ferrites. The average particle size was greatly minified by Zn2+ ion substitution, suggesting suppression of the crystal growth. Saturation magnetization and coercivity were increased with increasing x up to 0.3, and then they started to decrease at a particular molar ratio 0.5. Meanwhile, Mn-substituted ferrite samples evinced an initial decrease in the optical band gap energy from Eg = 1.19 to 1.16 eV with increasing x from 0.1 to 0.3, and then it increased to 1.27 eV at x = 0.5, while the optical band gap of Zn-substituted ferrite samples increased from 1.27 to 1.33 eV with increasing x from 0.1 to 0.5. Overall, the eco-friendly synthesis provides an efficient approach for tailoring the spinel ferrites with enhanced properties for wide range of magneto-optical applications.