The effect of heat treatment temperature on the microstructure and magnetic properties of Ba2Co2Fe12O22 (Co2Y) prepared by sol–gel method

Ferroxplana type hexagonal ferrite with composition Ba2Co2Fe12O22 (Co2Y) was prepared by polymeric sol–gel method from the aqueous solution of their corresponding metal salts. All the samples were characterized by using X-ray diffraction and scanning electron microscopic technique. The formation and the microstructure of the Ba2Co2Fe12O22 was studied as a function of heat treatment temperature and it was observed that well defined hexagonal plate-like fine particles with particle sizes between 130 and 400 nm were formed at relatively lower temperature (900 °C) as compared to conventional solid state reaction method (1100 °C). Magnetic properties of the samples were also studied as a function of heat treatment temperature and it showed large saturation magnetization (Ms) ranging from 30.9 to 47.6 emu/g and a wide range of coercivity (130∼1566 Oe) depending on the heat treatment temperature. The very high saturation magnetization at relatively lower temperature (say 800 °C) arises due to the presence of several high magnetic impurities, such as BaFe12O19 and CoFe2O4. The saturation magnetization increases with increasing heat treatment temperature above 900 °C, while the coercivity showed a reversed order.