Effect of stoichiometry on the phase formation and magnetic properties of BaFe12O19 nanoparticles by reverse micelle technique

Structure parameters and field-dependent magnetic properties of BaFe12O19 nanoparticles synthesized from different Fe/Ba ratios by reverse micelle technique were investigated. Pure barium ferrite phase and best magnetic properties could be obtained for the sample prepared from Fe/Ba ratio of 11, with grain size in the range of 20–30 nm as shown by TEM. The existence of α-Fe2O3 in other materials obviously decreases the magnetization properties, but coercivities of the materials from Fe/Ba ratio of 9.5 and 10 are abnormally even higher than the prepared pure BaFe12O19. The abnormal high coercivities of some prepared materials were explained from anisotropy mechanisms of nanoparticles.