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.