Preparation and magnetic properties of nanocrystalline BaFe12O19 and Ba (CoTi)xFe12-2xOi9 powders by the stearic acid gel method

摘要

M-type barium ferrite BaFenOi? has been widely studied because of its applicability to high density magnetic and magneto-optical recording media [lj. BaFei2Oi9 is usually doped with Co2+ in order to reduce the magnetocrystalline anisotropy. There are many methods of preparing barium ferrite, such as glass crystallization [2], conventional mixtures of oxides, coprecipitation and the liquid mix technique [3, 4]. The magnetic properties of the ferrite such as coercivity and remanence have been found to depend largely on the microstructure of these materials. The coercive force has been found to vary with the particle size and particle shape. In the work reported here, a relatively new and novel non-aqueous preparation method, the stearic acid gel method, was used in the preparation of barium ferrite and substituted barium ferrite. The main advantage of this technique is that the ions are mixed on an atomic scale in the liquid state itself, hence it is possible accurately to control the composition of the product in the initial stages of preparation. By this method, nanocrystalline substituted barium ferrite powders with size of 10-200 nm were obtained. The characterization focused on the chemical and structural as well as the magnetic properties of particles.