Dielectric and magnetic properties of ZnCo-substituted X hexaferrites prepared by citrate sol–gel process

Ba2Zn2−xCoxFe28O46 hexaferrites with x=2.0, 1.6, 1.2, 0.8, 0.4 and 0.0 were prepared by citrate sol–gel process. They were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetry-differential scanning calorimetry (TG-DSC). The frequency-response complex dielectric constant and complex permeability of Ba2Zn2-xCoxFe28O46 sintered at 1000–1200 °C had been investigated in the range from 100 MHz to 6 GHz. The pronounced natural resonance phenomena were observed in μ″ spectrum for the samples annealed at 1100 and 1200 °C. The natural resonance frequency of Ba2Zn2−xCoxFe28O46 ferrites was intensively affected by the substitution of Zinc ion and annealing temperature.