Electromagnetic and microwave absorbing properties of Co2Z-type hexaferrites doped with La

Z-type ferrites doped with La³⁺, Ba_3−xLa_xCo₂Fe₂₄O₄₁ (x=0.00-0.30), were prepared by sol-gel method. The effect of the substitution La³⁺ rare-earth ions for Ba²⁺ ions on the microstructure, complex permeability, permittivity and microwave absorption of the samples was investigated. The results show that the major phase of the ferrites changed to Z-phase when sintering temperature was 1250 °C for 5 h. With the increase of the substitution ratio of La³⁺ ions from 0.0 to 0.3, the lattice parameters a and c increased gradually, which resulted in the change of the particle shape and size. The data of magnetism showed that the addition of La³⁺ ions make the ferrite a better soft magnetic material due to increase of magnetization (σ_s) and decrease of coercivity (H_c). The La³⁺ ions doped in the ferrite not only improved complex permeability and complex permittivity, but also microwave absorbency.