Grain and grain boundaries contributions to dielectric relaxation of the clay-based ceramics

Mahani, Ragab; Omara, Shereen

doi:10.1007/s00339-019-2873-5

Cited by 11 publications

(9 citation statements)

References 38 publications

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“…The composition of AC plays an important role for resulting the ordered magnetic pore in composites. Transport of the charge carrier through the magnetic pore mainly limited by the intrinsic carrier mobility in the pore and contribution of the grain pore boundary scattering 43 . When these boundaries of the pore have ordered nature in the periodic structure by the increasing amount of AC in the composites, the bandgap and magnetic properties enhanced, subsequently the degradation performance increase.…”

Section: Resultsmentioning

confidence: 99%

“…40 The essential characteristics of the Langmuir isotherm can be shown in the dimensionless balance parameter (R L ), 40,42 limited by the intrinsic carrier mobility in the pore and contribution of the grain pore boundary scattering. 43 When these boundaries of the pore have ordered nature in the periodic structure by the increasing amount of AC in the composites, the bandgap and magnetic properties enhanced, subsequently the degradation performance increase. In contrast, when they have disordered in nature due to the small amount of the AC in composites, the bandgap and the magnetic properties is low, that is, the degradation ability is low.…”

Section: Resultsmentioning

confidence: 99%

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Decreasing charge recombination by magnetic trap of iron‐carbon (Fe‐AC) composite for enhanced photocatalytic performance

Tahir

Abdullah

Ilyas

et al. 2021

Surface & Interface Analysis

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Electronic properties of composite Fe and activated carbon (AC) were determined by using X‐ray photoelectron (XPS) and reflection electron energy loss (REELS), structural properties by X‐ray diffraction (XRD), and photo‐catalytic performance by ultra violet visible (UV‐Vis) spectroscopy. The intensity of low loss spectrum shows surface state at 5.42 eV is decreased with increasing the amount of AC indicated the Fe successfully oxidizes to form iron oxide. The bandgap was increased from 2.2 eV for 10% AC to 4.3 eV for 25% AC indicated the absorption wavelength shifted from the visible region to ultra‐violet region. The magnetic properties and porosity were increased with increasing the amount of AC in composites and show successfully used, as a magnetic trap of the charge (electron and hole) for producing radical atoms. The magnetic pore transformed from the disordered to ordered nature in the periodic structure was used to accelerate the degradation from 70.15% for 10% AC to 80% for 25% AC for 60 min. This study shows magnetic trap of composite Fe‐AC materials useful for enhanced photocatalytic performance.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Decreasing charge recombination by magnetic trap of iron‐carbon (Fe‐AC) composite for enhanced photocatalytic performance

Tahir

Abdullah

Ilyas

et al. 2021

Surface & Interface Analysis

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“…Taking into consideration, the electrode/interface effect (electrode polarization) occurs at lower frequency, GB at intermediate frequency, whereas G at higher frequency. Recently, for the 50/50 ceramic, we attributed the relaxation processes to the capacitive contributions of G and GB [21]. Similarly, the frequency and temperature dependence of εʹ and εʹʹ can be explained by considering the 40/60 ceramic as an inhomogeneous medium made of two Maxwell Wagner-type layers consisting of semiconducting grain (G) separated by insulating grain boundaries (GBs) [26,27].…”

Section: Permittivity and Dielectric Lossmentioning

confidence: 99%

“…Due to the complex structure of the conventional ceramics, little attention has been paid to studying their electrical or dielectric properties, where many anomalous results are difficult to interpret. Although we reported some enhancements in the dielectric properties of these ceramics, upon sintering at 1100 °C and adding LiF, B 2 O 3 , ZnO, or MnO [16][17][18][19][20][21], our physical understanding of the relaxation phenomenon is still poor. Therefore, in our recent published work, we tried to understand the relaxation phenomenon on the basis of grains and grain boundaries capacitive contributions, which are related to some defects such as oxygen vacancies and valence fluctuation of ions [21].…”

Section: Introductionmentioning

confidence: 99%

“…Although we reported some enhancements in the dielectric properties of these ceramics, upon sintering at 1100 °C and adding LiF, B 2 O 3 , ZnO, or MnO [16][17][18][19][20][21], our physical understanding of the relaxation phenomenon is still poor. Therefore, in our recent published work, we tried to understand the relaxation phenomenon on the basis of grains and grain boundaries capacitive contributions, which are related to some defects such as oxygen vacancies and valence fluctuation of ions [21]. To achieve that, Abu Khrug nepheline tailing (Eastern Desert, Egypt) and Wadi Abu Suberia clays (near Aswan, Egypt) were fined and wet homogenously mixed at the same ratios to produce the 50/50 ceramic.…”

Section: Introductionmentioning

confidence: 99%

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Effect of clay/nepheline tailing ratio on the dielectric relaxation and conduction mechanism of the conventional ceramic

Mahani

Omara

2022

Appl. Phys. A

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The dielectric relaxation and conduction mechanism of 40 wt% nepheline tailing and 60 wt% clay-based ceramic, i.e., the 40/60 ceramic, have been investigated over wide ranges of frequency and temperature, using a broadband dielectric spectrometer (BDS) and then compared with the data recently reported for the 50/50 ceramic. Both 40/60 and 50/50 ceramics were fabricated by grinding the raw materials to be very fine, wet homogenously mixing, drying and finally firing at 1200 °C. Their crystalline phases identified by X-ray diffraction were quartz, hematite, cristobalite, and albite. The 40/60 ceramic of lower glassy phase (nepheline tailing) content displays lower crystallinity than the 50/50 ceramic. Its conduction activation energies (Eac) show values between 0.12 and 0.32 eV, corresponding to the activation energy of oxygen vacancies (Vo++ ~ 0.22 eV). As oxygen vacancies migrate at relatively low operating voltages, the fabricated ceramics would be promising in manufacturing the random access memory (RAM), taking into consideration that the 50/50 ceramic is more useful than the 40/60 ceramic. As a result, nepheline tailing or the glassy phase component may generate more oxygen vacancies and thus enhance the ceramic electrical properties. Finally, the conduction mechanism of both ceramics is described via the correlated barrier hopping (CBH) model.

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Dielectric Relaxation and Ferroelectric Properties of PNN–PZT Ceramics with Different Ni/Nb Ratios

Shi

Zeng

Zheng

et al. 2022

Physica Status Solidi (a)

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0.35Pb(NixNb1−x)O3–0.65Pb(Zr0.39Ti0.61)O3 (x = 1/4,1/3,1/2 and 2/3) ceramics are prepared by the conventional solid reaction method and their structure, dielectric, and ferroelectric properties are studied. All compositions show tetragonal perovskite structure and Ni2+ segregated at grain boundaries in ceramics with high Ni/Nb (x = 1/2,2/3). Oxygen vacancies exist in nonstoichiometric ceramics and increase with the increase in Ni/Nb. Due to the pinning effect of defects, the P–E loops become unsaturated, accompanied by a softening–hardening transition. Dielectric relaxation is detected in both PNN–PZT(x = 1/2) and PNN–PZT(x = 2/3), and the activation energies of relaxation and conduction are calculated by Arrhenius law. The results show that both grain and grain boundary contribute to dielectric relaxation which can be explained on the basis of equivalent circuit containing two parallel RC elements connected in series. The relaxation at low frequency is induced by dipoles concentrating on the grain boundary while the relaxation at high frequency is attributed to the first ionization of oxygen vacancies in the grain.

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Grain and grain boundaries contributions to dielectric relaxation of the clay-based ceramics

Cited by 11 publications

References 38 publications

Decreasing charge recombination by magnetic trap of iron‐carbon (Fe‐AC) composite for enhanced photocatalytic performance

Decreasing charge recombination by magnetic trap of iron‐carbon (Fe‐AC) composite for enhanced photocatalytic performance

Effect of clay/nepheline tailing ratio on the dielectric relaxation and conduction mechanism of the conventional ceramic

Dielectric Relaxation and Ferroelectric Properties of PNN–PZT Ceramics with Different Ni/Nb Ratios

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