Ferrites are mostly ferrimagnetic ceramics and most of them contain iron ions. Since their discovery, they received a lot of attention because of their physical properties, which enable them to be utilized as permanent magnets or microwave absorbers. Those properties depend on the structure and composition of the ferrite. The magnetic properties can be altered by iso- or aliovalent substitution of the iron(III) cations.[1-6] By combining various di- to tetravalent cations, different structures can be obtained, which differ in the stacking of different blocks (S-, R- and T-block) along the crystallographic c-axis.[5-9] Those blocks consist of two, three or four hexagonal oxygen layers, respectively. The oxygen anions form various coordination polyhedra. Octahedra are occupied in every block. The S- and T-blocks display occupied tetrahedra and the R-block contains occupied trigonal bipyramids.
We study the impact of substitutions on structure and properties of ferrites and try to synthesize new types of ferrites.
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