Simple recipe to synthesize single-domain BaFe12O19 with high saturation magnetization

We report a new synthesis route for preparation of single-domain barium hexaferrite (BaFe12O19) particles with high saturation magnetization. Nitric acid, known as a good oxidizer, is used a mixing medium during the synthesis. It is shown that formation of BaFe12O19 phase starts at 800 degrees C, which is considerably lower than the typical ceramic process and develops with increasing temperature. Both magnetization measurements and scanning electron microscope micrographs reveal that the particles are single domain up to 100 degrees C at which the highest coercive field of 3.6 kOe was obtained. the best saturation magnetization of approximate to 60 emu/g at 1.5T was achieved by sintering for 2h at 1200 degrees C. Annealing at temperatures higher than 1000 degrees C increased the saturation magnetization, on the other hand, decreased the coercive field which was due to the formation of multi-domain particles with larger grain sizes. It is shown that the best sintering to obtain fine particles of BaFe12O19 occurs at temperatures 900-1000 degrees C increased the saturation magnetization, on the other hand, decreased the coercive field which was due to the formation of multi-domain particles of BaFe12O19 occurs at temperatures 900-1000 degrees C. Finally, magnetic interactions between the hard BaFe12O19 phase and impurity phases ware investigated using the stone-wohllfartt model. (C) 2009 Elsevier B.V. All rights reserved.