Effect of Al substitution on the structural, electric and impedance behavior of cobalt ferrite

Priya, A. Sathiya; Geetha, D.; Kavitha, Nowroji

doi:10.1016/j.vacuum.2018.12.004

Cited by 75 publications

(18 citation statements)

References 28 publications

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“…This electrically inhomogeneous structure suggested the Maxwell-Wagner (M-W) polarization effect as the origin of the giant relative permittivity of the current samples, as shown in Figure 3. M-W polarization ascribes the effect of the polarization that takes place at blocking interfaces and boundaries such as sample surface/electrode, grain/grain boundary, and domain/domain boundary [4,5]. Figure 6 depicts the Arrhenius plots for the conductivity of the grain, domain-boundary, and grain-boundary regions.…”

Section: Resultsmentioning

confidence: 99%

Dielectric Response and Structural Analysis of (A3+, Nb5+) Cosubstituted CaCu3Ti4O12 Ceramics (A: Al and Bi)

et al. 2020

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CaCu3Ti4-x((A0.05Nb0.05))xO12 ceramics (A: Al and Bi; x = 0, 0.3) were synthesized by high-energy mechanical ball milling and reactive sintering at 1050 °C in air. Rietveld refinement of XRD data revealed the pure and (Al3+, Nb5+) cosubstituted ceramics contained a minor CuO secondary phase with a mole fraction of about 3.2% and 6.9%, respectively, along with a CaCu3Ti4O12 (CCTO)-like cubic structure. In addition, (Bi3+, Nb5+) cosubstituted ceramics had a pyrochlore (Ca2(Ti, Nb)2O7) secondary phase of about 18%. While the (Al3+, Nb5+) cosubstituted CCTO showed the highest relative permittivity (ε’ = 3.9 × 104), pure CCTO showed the lowest dielectric loss (tanδ = 0.023) at 1 kHz and 300 K. Impedance-spectroscopy (IS) measurements showed an electrically heterogeneous structure for the studied ceramics, where a semiconducting grain was surrounded by highly resistive grain boundary. The giant relative permittivity of the ceramics was attributed to the Maxwell–Wagner polarization effect at the blocking grain boundaries and domain boundaries. The higher tanδ of the cosubstituted samples was correlated with their lower grain boundary’s resistivity, as confirmed by IS analysis. Modulus-spectrum analysis revealed two relaxation processes for the pure and (Bi3+, Nb5+) cosubstituted CCTO samples. Dissimilar behavior was observed for the (Al3+, Nb5+) cosubstituted CCTO, where three relaxation mechanisms were observed and attributed to the grain, domain-boundary, and grain-boundary responses.

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Section: Resultsmentioning

confidence: 99%

Dielectric Response and Structural Analysis of (A3+, Nb5+) Cosubstituted CaCu3Ti4O12 Ceramics (A: Al and Bi)

et al. 2020

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“…The characterization of M-CoFe 2 O 4 ferrites are done using the methods of X-Ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) [128][129][130][131], and atomic force microscopy (AFM). Magnetic behavior of ferrites are studied by vibrating sample magnetometry (VSM), electron spin resonance (ESR), hysteresis loop measurements, and magnetization hysteresis (M−H loops) [132] and many other methods.…”

Section: Characterization Methodsmentioning

confidence: 99%

Synthesis, Characterization, and Applications of CoFe2O4 and M-CoFe2O4 (M = Ni, Zn, Mg, Cd, Cu, RE) Ferrites: A Review

Kakati

Rendale²,

Mathad

2021

Int. J Self-Propag. High-Temp. Synth.

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“…Doping and thermal changes during synthesis and processing of cobalt-ferrites alter the distribution of metal ions influencing their structure and magnetic properties [7]. Priya et al [8] doped Al ions, with Cobalt ferrite nano particles. They observed that Al doped cobalt ferrite to be suitable for high frequency applications and magnetic memory devices.…”

Section: Introductionmentioning

confidence: 99%

Crystal Chemistry, Rietveld Analysis, Structural and Electrical Properties of Cobalt-Erbium Nano-Ferrites

Sumalatha¹,

Ravinder²,

Maramu³

et al. 2021

Ferrites - Synthesis and Applications

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Synthesis of Cobalt-Erbium nano-ferrites with formulation CoErxFe2-xO4 (x = 0, 0.005, 0.010, 0.015, 0.020, 0.025, and 0.030) using technique of citrate-gel auto-combustion was done. Characterization of prepared powders was done by using XRD, EDAX, FESEM, AFM and FTIR Spectroscopy, DC resistivity properties respectively. XRD Rietveld Analysis, SEM, TEM and EDAX analysis were taken up in studying spectral, structural, magnetic and electrical properties. XRD pattern of CEF nano particles confirm single phase cubic spinal structure. The structural variables given by lattice constant (a), lattice volume (v), average crystallite size (D) and X-ray density(dx), Bulk density (d), porosity (p), percentage of pore space (P%), surface area (s), strain (ε), dislocation density (δ), along with ionic radii, bond length and hoping length were calculated. SEM and TEM results reveal homogeneous nature of particles accompanied by clusters having no impurity pickup. TEM analysis gives information about particle size of nanocrystalline ferrite while EDAX analysis confirm elemental composition. Emergence of two arch shaped frequency bands (ν1 and ν2) that represent vibrations at tetrahedral site (A) and octahedral site(B) was indicated by spectra of FTIR. The samples electrical resistivity (DC) was measured between 30°C -600°C with Two probe method. XRD Rietveld analysis confirm crystallite size lying between 20.84 nm–14.40 nm while SEM analysis indicate formation of agglomerates and TEM analysis indicate particle size ranging between 24 nm–16 nm. DC Electrical measurements indicate continuous decrease in resistivity with increasing temperature while increasing doping decreases curie temperature. The Magnetic parameters such as Saturation magnetization (Ms), Remanent magnetization (Mr), Coercivity (Hc) and Squareness ratio (R = Mr/Ms), Magnetic moment (nB) were altered by doping of Er+3 content in the increasing order (x = 0.00 to 0.030). The increasing erbium content decreases magnetization thus converting the sample into soft magnetic material. Observations indicated strong dependence of magnetic properties on Erbium substitution and coercivity varies in accordance with anisotropy constant. Due to the presence of magnetic dipole Erbium substituted cobalt ferrites can be used in electromagnetic applications. The present study investigates the effect of different compositions of Er3+ replaced for Fe on structural properties and electrical resistivity of cobalt ferrites.

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Effect of Al substitution on the structural, electric and impedance behavior of cobalt ferrite

Cited by 75 publications

References 28 publications

Dielectric Response and Structural Analysis of (A3+, Nb5+) Cosubstituted CaCu3Ti4O12 Ceramics (A: Al and Bi)

Dielectric Response and Structural Analysis of (A3+, Nb5+) Cosubstituted CaCu3Ti4O12 Ceramics (A: Al and Bi)

Synthesis, Characterization, and Applications of CoFe2O4 and M-CoFe2O4 (M = Ni, Zn, Mg, Cd, Cu, RE) Ferrites: A Review

Crystal Chemistry, Rietveld Analysis, Structural and Electrical Properties of Cobalt-Erbium Nano-Ferrites

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