Formation mechanism of 3BaO·2CoO·12Fe2O3 powder synthesized using chemical coprecipitation

In this study, the formation mechanism of 3BaO·2CoO·12Fe2O3 (Co2Z) ferrite obtained using the coprecipitation method was investigated using thermogravimetry (TG), differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). It was found that the BaFe12O19 (BaM) phase was obtained directly from the BaCO3 and amorphous iron hydroxide reaction, with no α-Fe2O3 and BaFe2O4 formed as intermediates. The BaM and Ba2Co2Fe12O22 (Co2Y) phases coexisted in the calcined sample as the temperatures were ≦1000 °C. The BaM constituents then diffused into the lattice of Co2Y to form Co2Y*, having a Co2Y phase crystal structure and Co2Z chemical composition of at 1100 °C. The single Co2Z phase was obtained through nucleation and growth from the Co2Y and Co2Y* matrix at 1200 °C.