Influence of Fe2+ on microwave behaviour of M(Co, Ti)l,2 type hexaferrite

This work deals with M-type Co,Ti substituted barium hexaferrite, Ba(CoTi) x Fe 12-2x O 19 studied near the uniaxial-planar transition (x≥1,2). A single crystal state like was obtained by using textured ceramic. Our aim is to observe the effect of the divalent iron ions on the permeability curves. We have correlated the presence of Fe 2+ ions with the variation of the value of the permittivity e' at 0.1 GHz. The concentration of Fe 2+ ions has been varied by annealing the sintered materials under either reducing (N 2 ) or oxidizing (O 2 ) atmosphere. We have tried to interprete the important variations of the permeability in terms of domain wall and gyromagnetic contributions.