Substituted ferrites studied by nuclear methods

We report on recent investigations on substituted hexaferrites of the type SrM, Sr 1-x La x Fe 12-x Co x O 19 (0 ≤ x ≤ 0.4). It was already proved that the simultaneous substitution of Sr and Fe by La and Co, respectively, significantly improves the permanent magnetic properties of the material. In order to get a deeper insight into the magetic order from an atomistic point of view, 57 Fe Mossbauer spectroscopy and NMR ( 57 Fe, 59 Co) studies were carried out. It is demonstrated that by applying local probe hyperfine techniques the knowledge about this complex material can be considerably improved. The main results concern the preferred Co 2+ occupation on the 4f 2 and the 2a sites and the occurrence of Fe 2+ ions in the substituted material.