Structure and magnetic properties of CuO-substituted Co₂Y hexaferrites for high frequency applications

In this paper, Cu-substituted Y-type hexaferrite Ba₂Co_2−xCu_xFe₁₂O₂₂ (x = 0.0, 0.2, 0.4, 0.6, 0.8) materials were prepared by solid state reaction method. The structure and magnetic properties of ferrite have been investigated. CuO substitution not only adjusted structure and magnetic properties of sample, but also lowered sintering temperature. CuO modification endowed Co₂Y hexaferrites with better magnetic properties: dense microstructure, appropriate saturation magnetization, low coercivity and high permeability in high frequency. Light CuO improved grain morphology, when CuO was added from 0.0 to 0.8, saturation magnetization increased from 31.7 emu/g (x = 0.0) to 32.3 emu/g (x = 0.2), and then decreased to 27.74 emu/g (x = 0.8). Meanwhile, coercivity decreased from 172 Oe to 136 Oe with x from 0.0 to 0.8. The real part of magnetic permeability increased from 1.88 to 2.85 with Cu substitution. The imaginary part increased kept less than 0.25 and magnetic loss kept low value of 0.08 at 0.1–1 GHz frequencies. DC resistivity of the ferrites first increased from 3.65 × 10⁵ Ω cm (x = 0.0) to 9.81 × 10⁵ Ω cm (x = 0.4), and then decreased to 3.14 × 10⁴ Ω cm (x = 0.8).