Magnetic properties, compositions, and microstructures of high-energy product strontium hexaferrites

Commercial, high-energy product strontium hexaferrites have been characterized in terms of their chemical compositions, microstructures, and bulk and submicroscopic magnetic properties. Compared to earlier permanent magnetic hexaferrites, these materials have a unique composition, containing no elements other than Sr and Fe at appreciable concentrations; dopants for nucleation and microstructure control are apparently absent. The microstructures indicate that, in some cases, the materials may be fully reacted prior to forming the final ceramic bodies. The compositions are variable and tend to be nonstoichiometric despite the absence of impurity elements. These deviations from stoichiometry are reflected in the Mössbauer spectra which indicate that further refinements can be made in the definition of the different magnetic sublattices. These refinements may lead to further advances in the magnetic properties.