Effect of Ce3+ substitution on the structural, morphological, dielectric, and impedance spectroscopic studies of Co–Ni ferrites for automotive applications

Abstract

Cerium (Ce 3? )-substituted cobalt-nickel (Co-Ni) ferrite nanostructures of spinel cubic phase with space group Fd 3m had been successfully engineered by solution combustion route. The effect of Ce 3? substitution on the structural, morphological, dielectric, and impedance spectroscopic investigations are probed by using X-ray diffraction (XRD), scanning electron microscope (SEM), and impedance analysis, respectively. Rietveld refinement of XRD data reveal that samples exhibit well-crystalline nature with single phase. The microstructural realm with various Ce 3? doping levels has been identified from SEM micrographs. The replacement of Fe 3? by Ce 3? cations has been confirmed by using energydispersive analysis of the ferrite samples. The dielectric constant (e 0 ), dielectric loss (tand), ac conductivity (r ac ), and impedance (Z 0 and Z 00 ) at room temperature is investigated as a function of frequency, respectively. The variation of dielectric properties e 0 , tand, r ac with frequency are explained by Maxwell-Wagner type of interfacial polarization and the hopping of charge between Fe 2? and Fe 3? as well as the dopant ions at B-sites. The decrease in dielectric constant and dielectric loss tangent with frequency follows the phenomenon of Debye's relaxation. The enhancement in AC conductivity with frequency is proportional to Ce 3? concentration which follows Jonscher law. The complex impedance plots (Z 0 vs. Z 00 ) allows to determine the contribution for conductivity either from grain or grain boundary. Complex electric modulus plot (M 0 vs. M 00 ) provides the validation to the result drawn from the complex impedance plots. The results indicate the existence of non-Debye type of relaxation in these ferrites. Impedance spectroscopy allows the ferrite materials to estimate electrical properties which arise due to hopping and relaxation phenomena.

Enhanced Humidity Sensing Response in Eu3+-Doped Iron-Rich CuFe2O4: A Detailed Study of Structural, Microstructural, Sensing, and Dielectric Properties

“…The Cole-Cole plots between the real part of the electric modulus and imaginary parts of the electric modulus can give good results. The role of grains and grain boundaries is very good because semicircles are observed at all the samples [9,12]. The maximum peak of the diameter observed semicircle increases with the substitution of europium rare earth ions.…”

“…The ionic radii of Fe 3+ (0.67 Å) are lesser than that of Eu 3+ (0.99 Å) ions; this confirms the occupancy of europium on an octahedral site. The average crystallite size of CuFe 2Àx Eu x O 4 (where x = 0.00, 0.01, 0.02, 0.03) nanoparticles estimated from the Debye-Scherrer relation and the average particle size of all the samples were found to be in the range of 16-51 nm [9]. The strain values are calculated by using equation ɛ ¼ βcosθ = 4 and are tabulated in Table 1.…”

Impact of Annealing Temperature on Electrical Properties of Sol-gel Ba0.90Gd0.10TiO3 Thin Films

“…The figure shows that, at low frequencies < 10 3 Hz, the dielectric loss is slightly high and it dramatically decreases with frequency. The high value of tanδ at low frequencies is due to accumulated charge at the grain boundaries and film/electrode interfaces that harden the electrons transaction between the lattice sites, which in turn requires higher energy, thus, the loss would be higher [18]. At a higher frequency range, from 10 4 Hz to 10 5 Hz, tanδ becomes almost frequency independent and it is relatively low (< 0.5), which denotes the quality of the films.…”

Synthesis and Study of Structural and Dielectric Properties of Dy-Ho Doped Mn-Zn Ferrite Nanoparticles

“…This Ferrite behavior could be explained by using Koop's theory. In the lower frequency zone, the electrons exchange between ions follows the applied electric field and is responsible for high value of ε' [26]. Due of high conducting grains, the ε' is frequency independent at higher frequency region.…”