The formation mechanism of MnZn ferrite by the CTAB-assisted synthesis

MnZn ferrite powders were prepared, based on the novel nano-in-situ composite method and through chemical sol–spray–calcination technology. Different dosage of CTAB were used, and the influences on the precursor sol solutions and precursor powders were studied. Also, the selected precursor powders (P-0.1CTAB) were calcined at 1060 °C in air for 3 h, and the sample (S-0.1CTAB) was considered to further exploration. The results indicated that the precursor sol and precursor powders were in their optimal state when adding 0.1 wt.% CTAB. Under this condition, the Zeta potential of the sol was 10.7 mV, and the colloidal particle size was 91.63 nm. The corresponding precursor powders can still maintain a nanoscale fine particle composition and be well dispersed. The S-0.1CTAB sample with hollow spherical shell composed of small particles of several hundred nanometers had pure MnZn ferrite phase, and the maximum value of saturation magnetization (M_s) was 53.46 emu/g. Moreover, there are three stages of the formation of MnZn ferrite during the CTAB-assisted synthesis process which are CTAB ionization and (Mn, Zn, Fe)(OH)(NO₃)(H₂O) formation stage, CTA + adsorption and colloidal particle formation stage, and (Mn, Zn, Fe)(OH)(NO₃)(H₂O) decomposition stage.