Magnetic and dielectric properties of MgxCo1-xFe2O4 ferrites prepared by the sol-gel method

Highlights: • Grain size decreases as the Mg²⁺ concentration increases from x = 0.2 to x = 1.0. • Ms value decreases rapidly when Mg²⁺ doping changed from x = 0.4 to x = 0.6. • Saturation field drop down to 0.75 kOe when Mg²⁺ doping changed from x = 0.2 to x = 1.0. • Only one arc existed in Z ' - Z ″ plot due to co-effect of grain and grain boundary. - Abstract: Mg_xCo_1-xFe₂O₄ ferrites were prepared by the sol-gel method and sintered from 1100 °C to 1300 °C. The microstructures, magnetic and dielectric properties have been investigated. XRD patterns demonstrated that the samples have a single spinel phase with cubic symmetry. Mg²⁺ doping expands the lattice parameter slightly. The grain size increases with increasing sintering temperature but decreases with Mg²⁺ doping. The saturation magnetization value decreases from 64.26 emu/g to 26.05 emu/g with the increasing Mg²⁺ concentration from x = 0.2 to x = 1.0. And the coercivity of the samples also decreases from 0.32 kOe to 0.15 kOe. The dielectric results showed that the behavior of dispersion appeared at the low frequency, which can be attributed to the space charge polarization. And the dielectric constant increases with the increasing grain size. All the results indicated that the Mg²⁺ doping has a significant influence on the properties of CoFe₂O₄.