Thickness Dependent Dielectric Properties Of CFO-PZT-CFO Tri-layered Composites

Objectives: The main objective of the present research is to synthesize CoFe2O4 (CFO) and PbZr0.52Ti0.48O3 (PZT) materials in nanoform and to fabricate the tri-layered structures to study the dielectric properties. Method: CoFe2O4 (CFO) and PbZr0.52Ti0.48O3 (PZT) materials are synthesized by using combustion method. Glycine (C2H5NO2 ) was used as fuel. X-ray diffraction (XRD) technique is used to study the crystal structure . Tri-layered structures of CFO/PZT/CFO are fabricated by co-pressing the CFO and PZT powders. The dielectric measurements are carried out on tri-layered pallet samples in the frequency range 10 Hz-10MHz. Findings: The XRD studies reveal the single phase formation in each case. The dielectric constant (ε’) decreases with increase in frequency of the applied AC field; rapidly at low frequency side and then remain unaltered at higher frequency region. The dielectric dispersion is observed at low frequency region and is attributed to the inhomogeneity in the microstructure of the samples. The rapid decrease of dielectric constant at lower frequency region with increase in frequency is caused due to failure of the hopping frequency of the charge carriers to follow the frequency of the applied AC electrical field. The variation of dielectric loss tangent with frequency follow the same trend as that of dielectric constant , however the samples with low thickness PZT layer show loss maxima in the frequency range 50 Hz-1000Hz. The AC electrical conductivity of the present composites remains unaltered up to 10 kHz frequency of the applied field and then increase abruptly beyond that limit because of increase in hopping frequency of the charge carriers. The linearity in Log(σAC-σDC) vs. Log (ω2) plot indicates that the small polaron hopping mechanism is responsible for the conductivity process in these composites. Novelty: No reports are found in the literature on the co-axial pressing of CFO and PZT materials alternatively to make tri-layered structures. Also, no reports are found on the dielectric properties of the tri-layered structures of CFO and PZT. Keywords: Ferrites, Ferroelectrics, Composites, Dielectrics, XRD