Structural and magnetic studies on barium hexaferrites prepared by mechanical alloying and conventional route

In the present study, barium hexaferrite powders were prepared by ordinarily mixing and by high energy ball-milling stoichiometric amounts of the BaCO3 and Fe2O3 precursors, followed by heat treatments carried out in the 900–1100 °C range of temperature. The structural and magnetic properties of the resulting powders were analyzed by differential thermal analysis, X-ray diffraction, scanning electron microscopy, Mössbauer spectroscopy and magnetization measurements. The milled powder showed a lower decomposition temperature and higher surface area than the ordinarily mixed powder. Formation of the BaFe2O4 intermediate phase was observed in conventionally prepared hexaferrites. Diversely, the mechanical process before annealing allowed for the hexaferrite formation at much lower temperatures but without formation of intermediate phases. The hyperfine parameters showed to be independent of the processing method. Higher saturation magnetization, and coercivity were observed in the barium hexaferrites prepared by high energy ball milling.