Improvement of ceramic method for synthesizing M-type hexaferrites

Abstract The aim of this paper is to improve the standard ceramic method for the synthesis of hexaferrites, studying several alternatives to the usual raw materials of iron and barium oxides and new ways of developing the wet-milling. The research has been focused in the two first stages (the so-called red-milling and the presintering or calcination step) of this process, optimizing their variables. They are type of milling-fluid, temperature and time of calcination, heating rate and BaO/Fe2O3 molar ratio. The optimization variable was the coercive field. The use of iron oxides different than α-Fe2O3 yields hexaferrites with magnetic properties higher than commercial ones. Thus, these hexaferrites are optimum as permanent magnets and can replace other more expensive magnets.