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

Abstract

The titration order effect on the 3BaO·2CoO·12Fe 2O 3 (Co 2Z) 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 Co 2Z phase prepared using coprecipitation was obtained by the reaction of two previous formed BaFe 12O 19 (BaM) and Ba 2Co 2Fe 12O 22 (Co 2Y) phases. For the sample obtained using back titration, the BaM phase was obtained directly by reacting BaCO 3 and amorphous iron hydroxide with no α-Fe 2O 3 and BaFe 2O 4 formed as intermediates. However, owing to the existence of coarsened α-Fe 2O 3 and BaFe 2O 4 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 Co 2Y 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 Co 2Z phase formation temperature for the sample obtained by direct titration having a higher temperature than that by back titration.