Synthesis and characterization of ferrite-ferroelectric nanocomposite thick films

The Magnetoelectric nanocomposites of ferrite and ferroelectric phases having general formula [NixCu1−xFe2O4] – [PbZr0.52Ti0.48O3] (where x = 0.3, 0.4, 0.5, 0.6, 0.7 and 0.9) are synthesized by self-propagating auto combustion method. The X-ray diffraction study revealed the coexistence of spinel structure in the ferrite phase and perovskite structure in the ferroelectric phase. Screen printing technique is used to fabricate thick films of these composites on fluorine-doped tin oxide (FTO) coated glass substrates. The average grain size obtained from the SEM study is in the range 100–400 nm. The dielectric properties are studied in the frequency range from 100 Hz to 1 MHz. The low-frequency dispersion is attributed to the difference in composition of the ferrite phase. The dielectric constant remains invariant under the frequency studied. The tanδ vs. log(ω) plot shows the absorption peaks in the mid-frequency range studied due to the resonance phenomenon. The rapid fall of AC resistivity with rise in frequency is attributed to the increase in the hopping frequency of charge carriers between the equivalent ionic sites in the lattice. The linearity in logσ vs. log(ω2) plot confirmed the presence of a small polaron hopping mechanism. The curves in the dielectric constant vs. temperature plot are flat indicating that the dielectric mechanism is not activated in the temperature range studied. The log(ρ) vs. 1000/T plot exhibited the semiconducting nature in present composites. The Magnetoelectric(ME) voltage coefficient vs. dc bias field plot show peaks around 200 Oe which is due to the enhanced domain wall movements. The ME effect ceases beyond 400 Oe.