Effect of pelletization on magnetic properties of BaFe12O19

Barium hexaferrite has been synthesized by three different routes, namely oxidation in nitric acid, solid state reaction and co-precipitation. It was shown that pelletizing before the sintering favors the formation of BaFe12O19 phase when metallic oxides are used as starting materials (i.e. through the first two methods) by increasing the reaction rates of the precursors. Thus, improvement in the saturation magnetization was observed in these samples, whereas the coercive field remained nearly the same with and without pelletizing. Magnetic interactions investigated using the Stoner-Wohlfarth model showed that demagnetizing-like interactions become stronger in the pelletized samples prepared by oxidation in nitric acid and solid state reaction routes. However, this interaction was suppressed in the pelletized sample prepared using co-precipitation technique by reducing the fraction of antiferromagnetic Ba2Fe6O11 phase. (C) 2009 Elsevier B.V. All rights reserved.