Microwave Based Synthesis; Structural, Optical and Magnetic Measurements of Co²⁺ Doped MnFe₂O4.

CO²⁺ doped manganese ferrite (Mn₁₋xCoxFe₂O₄, x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5) samples were synthesized by a microwave combustion method. Nitrates of the constituent elements and urea were respectively used as the oxidizer and fuel to drive the reaction. On an average a yield of 80% were obtained for all the compositions. Light-absorbing properties from UV-Vis diffuse reflection spectrum were studied and the results infer that the band gap energy (Eg) of the pure MnFe2O4 is 1.76 eV and with increase in C02+ ion concentration, it increases to 2.25 eV. The phase purity and crystal lattice symmetry were estimated from X-ray diffraction (XRD) and was identified as the spinel cubic crystal structure. The lattice parameter is found to decrease with an increase in Co content. The crystallite size was in the range of 19-25 nm. The purity and the composition of the elements were further confirmed by energy dispersive X-ray (EDX) results. Microstructural features obtained by scanning electron microscope (SEM) demonstrate that the nanocrystals were formed with a decrease in average grain size with C02+ content. Room temperature magnetic measurement for stoichiometric samples is discussed with the help of vibrating sample magnetometer (VSM). The saturation magnetization (M), remanant magnetization (Mr) and coercivity (H.) are measured from the respective hysteresis plots.