High Frequency Properties of Li Substituted Co₂Z Hexagonal Ferrites

Abstract

Z-type hexagonal ferrite samples with Ba₃Co_2-2xLi_xFe_24+xO₄₁ (x=0∼1.0) were prepared from stoichiometric mixtures of BaCO₃, CoO, Li₂Co₃ and α-Fe₂O₃, by calcinning at 1250°C and then sintering at 1275°C. The single phase of the Z-type was confirmed for the crystal structure of these samples with x=0∼0.5 by X-ray diffraction analysis. The sample with x=0 showed μ' of 8 at 50MHz. The maximum μ' was 24.5 at x=0.3. The Snoek's product of μ' × fr was 9GHz at x=0 and then increased to 15GHz at x=0.1∼0.3. The bulk density took a maximum at x=0.3, and the coercivity had a minimum at x=0.3. Therfore, high frequency properties of Co₂Z ferrite are specifically improved by the Li⁺−Fe³⁺ ions substitution with x=0.3.