Microwave behaviour in Z-type polycristalline hexaferrites

Abstract
The hexaferrites present today a great interest in the field of electromagnetic waves absorbents. We have studied Ba₃Co₂Fe₂₄O₄₁ Z-type hexaferrites. The origin of magnetic permeability in such polycrystalline materials is not so far perfectly known, especially in terms of relations between properties and microstructure. The purpose of this paper is to illustrate some of the issues involved in designing ferrite materials. On the one hand we have dealt with the relation between the elaboration conditions of the materials and their microstructure. On the other hand the influence of the microstructure on microwave behaviour has been studied. Investigated materials were in an intermediate state between the poly and single crystalline one.