Synthesis, structural investigation, dielectric and magnetic properties of Zn2+-doped cobalt ferrite by the sol–gel technique

Zinc substituted cobalt ferrite nanoparticles with elemental composition Co1−xZnxFe2O4 (x=0.0, 0.2, 0.4, 0.6) were prepared by the sol-gel auto-combustion technique using Co, Fe, Zn nitrate as a precursor where nitrates to citrate was 1:3. The as prepared powder of cobalt zinc ferrite was sintered at 900∘C for 3h. Structural, morphological, dielectric and magnetic properties were studied by x-ray diffractometer (XRD), scanning electron microscope (SEM), high precision impedance analyzer and vibrating sample magnetometer (VSM), respectively. The peaks obtained from the XRD confirmed samples having crystallite (∼32–36nm) single phase inverse spinel structure without any traceable impurity. Lattice parameters were calculated from XRD and it increases with Zn content. SEM revealed irregularly shaped grains (∼0.5–0.7μm) morphology with heterogeneous distribution. The dielectric constant (ε′) and dielectric loss (tanδ), have been measured as a function of frequency at room temperature. The dependence of ε′ and tanδ with frequency showed the normal dielectric behavior in accordance with the Maxwell-Wagner type of interfacial polarization and electron hopping change between Co2+ and Co3+ as well as between Fe2+ and Fe3+ ions at octahedral sites.