Synthesis of 3BaO·2CoO·12Fe2O3 powder using chemical coprecipitation

The titration order effect on the 3BaO·2CoO·12Fe2O3 (Co2Z) ferrite formation mechanism is obtained using the coprecipitation method. This process is investigated using thermogravimetry (TG), differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and superconducting quantum interference device (SQUID) magnetometer. It was found that Co2Z phase prepared using coprecipitation was obtained by the reaction of two previous formed BaFe12O19 (BaM) and Ba2Co2Fe12O22 (Co2Y) phases. For the sample obtained using back titration, the BaM phase was obtained directly by reacting BaCO3 and amorphous iron hydroxide with no α-Fe2O3 and BaFe2O4 formed as intermediates. However, owing to the existence of coarsened α-Fe2O3 and BaFe2O4 in the calcined sample obtained using direct titration, the crystallite size of the formed BaM for the sample obtained using direct titration was larger than that by back titration. Consequently, the reactivity of the formed BaM and Co2Y phases for the samples obtained using direct titration were lower than those by back titration due to the larger crystallite sizes, which led to the Co2Z phase formation temperature for the sample obtained by direct titration having a higher temperature than that by back titration.