The preparation and microwave properties of Ba₃Zn_ZCo_2-ZFe₂₄O₄₁/SiO₂ microcrystalline glass ceramics by citrate sol-gel process

Abstract 

A series of Ba₃Zn_ZCo_2-ZFe₂₄O₄₁/SiO₂ microcrystalline glass ceramics with Z=0.0,0.4,0.8 and 1.2 were prepared by citrate sol-gel process. The result showed that Ba₃Zn_ZCo_2-ZFe₂₄O₄₁ hexferrite crystallites could be obtained by this process at 1200 °C in the system of BaO-Fe₂O₃-CoO-ZnO-SiO₂. The complex dielectric constant and complex permeability of Ba₃Zn_ZCo_2-ZFe₂₄O₄₁/SiO₂ microcrystalline glass ceramics calcined at different temperature were measured in the range of 200MHz-6 GHz by transmission/reflection coaxial line method. The complex dielectric constant and dielectric loss exhibited insignificant variety in the whole range of measuring frequencies for all samples. The real part of the permeability decreased as the measuring frequency increasing, and calcining temperature had a clear influence on the value of µ′ for Ba₃Zn_ZCo_2-ZFe₂₄O₄₁/SiO₂ microcrystalline glass ceramics, and so did the content of Zn²⁺ and Co²⁺. The natural resonance phenomenon was observed in µ′′ spectra for all the Ba₃Zn_ZCo_2-ZFe₂₄O₄₁/SiO₂ microcrystalline glass ceramics. The substitution of Zn²⁺ ion and annealing temperature closely affect the resonance frequency, the more the Zn²⁺ ion, the higher the annealing temperature and the lower the resonance frequency.