Dielectric and magnetic properties of CoFe2O4 prepared by sol-gel auto-combustion method

Cobalt ferrite powders were successfully synthesized by sol-gel auto-combustion method. Influence of sintering temperature on structural, magnetic and dielectric properties was studied. All the obtained samples are spinel ferrite with a cubic symmetry. As the sintering temperature increased from 900 °C to 1300 °C, the average grain size increased from 0.26 μm to 0.83 μm. The dielectric constant and loss tangent measurement showed strong temperature dependence at all frequencies. The maximum magnetization increased while the coercivity and remanent magnetization decreased with the increasing sintering temperature. The non-saturation at high fields may be related to the surface effects in CoFe2O4 samples. When sintered at 1300 °C, the sample showed a maximum magnetization value of ∼87.32 emu/g at room temperature. The highest value of coercivity of all the samples was 1368.33 Oe for the sample sintered at 900 °C.