Electrical conductivity and dielectric relaxation of cerium (IV) oxide

El-Nahass, M.M.; Hassanien, A.M.; Atta, A.A.; Ahmed, Emad M.; Ward, Azza A.

doi:10.1007/s10854-016-5688-6

Cited by 14 publications

(14 citation statements)

References 56 publications

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“…In the NCL model, which was observed to fit in different material families, the AC conductivity depends linearly on frequency [49,50]. NCL model also indicates a negligible angular frequency dependence of e¢¢ [47]. Additionally, this model represents a localized hopping of charge carriers without any significant translational motion.…”

Section: Ac Conductivity Analysesmentioning

confidence: 90%

“…According to Jonscher's power law, the AC conductivity can be divided into two parts: the frequencyindependent component (s DC ) and the frequency-dependent component ( w A , s where A is a constant and s is a temperature-dependent frequency exponent, which takes values between zero and one) [46]. The temperature dependence of the frequency exponent s indicates the AC conduction mechanism in the materials since it identifies the degree of interaction between mobile carriers and environments surrounding them [47].…”

Section: Ac Conductivity Analysesmentioning

confidence: 99%

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MWCNT induced negative real permittivity in a copolyester of Bisphenol-A with terephthalic and isophthalic acids

Özdemir

Daşdan

Kavak

et al. 2020

Mater. Res. Express

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In the present study, the negative real permittivity behavior of a copolyester of bisphenol-A with terephthalic acid and isophthalic acid (PAr) containing 1.5 to 7.5 wt% multi-walled carbon nanotubes (MWCNTs) have been investigated in detail. The structural and morphological analysis of the meltmixed composites was performed by Fourier transform infrared spectroscopy using attenuated total reflection (FTIR-ATR), atomic force microscopy (AFM), x-ray diffraction (XRD), and light microscopy. The influences of the MWCNT filler on the AC impedance, complex permittivity, and AC conductivity of the PAr polymer matrix were investigated at different operating temperatures varied between 296 K and 373 K. The transition from a negative to positive real permittivity was observed at different crossover frequencies depending on the MWCNT content of the composites whereas pure PAr showed positive values at all frequencies. The negative real permittivity characteristic of the composites was discussed in the context of Drude model.

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Section: Ac Conductivity Analysesmentioning

confidence: 90%

Section: Ac Conductivity Analysesmentioning

confidence: 99%

MWCNT induced negative real permittivity in a copolyester of Bisphenol-A with terephthalic and isophthalic acids

Özdemir

Daşdan

Kavak

et al. 2020

Mater. Res. Express

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“…The dielectric constant (ε′) and the dielectric loss (ε″) are obtained from the following relation [26]:…”

Section: Characterizationsmentioning

confidence: 99%

“…The real Z′(ω) and imaginary Z″(ω) parts of the complex impedance are calculated using the following mathematical expressions [26]:…”

Section: Characterizationsmentioning

confidence: 99%

Enhanced optical and electrical properties of CeO₂NPs/chitosan nanocomposites

Ahmed

Alkathiri

2022

Mater. Res. Express

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Cerium oxide nanoparticles (CeO2NPs) of different ratios (x = 5, 10, 15, and 20 in wt.%) are successfully incorporated into chitosan (CS) to synthesize CeO2NPs/CS nanocomposites by solution cast method. FTIR and XRD analysis confirmed the effective incorporation of CeO2NPs into chitosan nanocomposites. TGA and DTG showed that the thermal stability of the as-prepared nanocomposites is improved. The CeO2NPs/CS nanocomposites exhibited enhanced light absorption capacity in the UV-visible range as x increases, owing to the CeO2NPs' large bandgap. The transmittance of UV decreased for x = 10 and 15 nanocomposites. Light scattering enhanced for x = 5 and 10 nanocomposites, increasing reflectance. Compared to CS (5.3 eV), the optical energy bandgap lowers to 4.94 eV and 5.1 eV, respectively. Impedance spectroscopy research validates the impedance spectroscopy parameters' dependency on CeO2NPs concentrations. Because of the growth of multiple polarization types, generating interfaces of numerous defects, and space charge polarization, the dielectric constant increases with increasing x (up to x = 15). The dc conductivity (σ DC) and the frequency exponent (S) are estimated using the universal Josher's power law and applied to the ac conductivity data (σ AC). Obviously, (S) decreases with increasing temperature, which refers to the electrical conductivity that follows the hopping mechanism. In addition, according to the CBH model, the Coulomb barrier of charge carriers (Um) is estimated, showing decreasing values as increasing x and recording the lowest value for x =15 nanocomposites. Nyquist plots (Z"&Z') indicate one semicircle arc behavior for all samples. As x rises, the radius of semicircular arcs reduces, suggesting that (σ DC) increases. The enhanced characteristics of CeO2NPs/CS nanocomposites make them suitable for future bio-applications.

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“…Was die Aufladung der Oberfläche betrifft, so wurde ein ähnliches Verhalten zuvor für CeO 2 bei Raumtemperatur beobachtet. [32] Das Vorhandensein eines begrenzten Diffusionsbereichs resultiert aus der erschwerten Sauerstoffanreicherung auf der In 2 O 3 -Oberfläche. Die an die Probe angelegte Spannung bewirkt aufgrund des nichtleitenden Charakters von In 2 O 3 bei Raumtemperatur eine externe Polarisierung, und die Aktivierungsenergie von 137 kJ mol À 1 aus dem temperaturabhängigen Leitfähigkeitsverhalten wird nicht durch eine einfache Polarisierung erreicht, sondern erfordert höhere Temperaturen.…”

Section: Ergebnisse Und Diskussionunclassified

Aufklärung der CO₂‐Hydrierung über In₂O₃‐Nanopartikeln mittels Operando UV/Vis‐ und Impedanzspektroskopie

et al. 2022

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Während sich In2O3 als vielversprechender Katalysator für die CO2‐Aktivierung erwiesen hat, fehlt bisher ein grundlegendes Verständnis seiner Funktionsweise bei der CO2‐Hydrierung, da die Anwendung der operando‐Schwingungsspektroskopie aufgrund von Absorptionseffekten eine Herausforderung darstellt. In dieser mechanistischen Studie untersuchen wir systematisch die Redox‐Prozesse im Zusammenhang mit der reversen Wassergas‐shift‐Reaktion (rWGSR) über In2O3‐Nanopartikeln, sowohl an der Oberfläche als auch in der Bulkstruktur. Basierend auf temperaturabhängigen operando‐UV/Vis‐Spektren und einem neuartigen operando‐Impedanz‐Ansatz für thermische Pulverkatalysatoren schlagen wir die Oxidation durch CO2 als den geschwindigkeitsbestimmenden Schritt für die rWGSR vor. Die Ergebnisse stimmen mit Redox‐Prozessen überein, wobei wasserstoffhaltige Oberflächenspezies nachweislich eine fördernde Wirkung aufweisen. Unsere Ergebnisse zeigen, dass für die Aktivität neben Oberflächenprozessen die Sauerstoff/Wasserstoff‐Dynamik wichtig ist, was nicht nur für In2O3, sondern auch für andere reduzierbare Oxidkatalysatoren von Bedeutung sein dürfte.

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Electrical conductivity and dielectric relaxation of cerium (IV) oxide

Cited by 14 publications

References 56 publications

MWCNT induced negative real permittivity in a copolyester of Bisphenol-A with terephthalic and isophthalic acids

MWCNT induced negative real permittivity in a copolyester of Bisphenol-A with terephthalic and isophthalic acids

Enhanced optical and electrical properties of CeO₂NPs/chitosan nanocomposites

Aufklärung der CO₂‐Hydrierung über In₂O₃‐Nanopartikeln mittels Operando UV/Vis‐ und Impedanzspektroskopie

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Electrical conductivity and dielectric relaxation of cerium (IV) oxide

Cited by 14 publications

References 56 publications

MWCNT induced negative real permittivity in a copolyester of Bisphenol-A with terephthalic and isophthalic acids

MWCNT induced negative real permittivity in a copolyester of Bisphenol-A with terephthalic and isophthalic acids

Enhanced optical and electrical properties of CeO2NPs/chitosan nanocomposites

Aufklärung der CO2‐Hydrierung über In2O3‐Nanopartikeln mittels Operando UV/Vis‐ und Impedanzspektroskopie

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Product

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Enhanced optical and electrical properties of CeO₂NPs/chitosan nanocomposites

Aufklärung der CO₂‐Hydrierung über In₂O₃‐Nanopartikeln mittels Operando UV/Vis‐ und Impedanzspektroskopie