Zur Theorie der unvollkommenen Dielektrika

Wagner, Karl W.

doi:10.1002/andp.19133450502

Cited by 1,392 publications

(408 citation statements)

References 8 publications

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“…Hence, the values of dielectric parameters increase. The high value at lower frequency region is due to Maxwell-Wagner interfacial type of polarization [20,21] for the inhomogeneous double layer dielectric structure, which is in agreement with Koop's phenomenological theory [22]. The inhomogeneous dielectric structure was supposed to be consisted of two layers.…”

Section: Resultssupporting

confidence: 63%

Frequency and temperature dependent transport properties of NiCuZn ceramic oxide

Hossen

Hossain

2015

Materials Science-Poland

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A polycrystalline sample of ceramic oxide Ni 0.27 Cu 0.10 Zn 0.63 Fe 2 O 4 was prepared by the solid state reaction method. The sintered sample was well polished to remove any oxide layer formed during sintering and the two surfaces of the pellet were coated with a silver paste as a contact material. Among dielectric properties, complex dielectric constant (ε * = ε − jε ), loss tangent (tanδ) and ac conductivity (σ ac ) in the frequency range of 20 Hz to 2 MHz were analyzed in the temperature range of 303 to 498 K using a Wayne Kerr impedance analyzer (model No. 6500B). The experimental results indicate that ε , ε , tanδ and σ ac decrease with an increase in frequency and increase with increasing temperature. The transition temperature, as obtained from dispersion curve of ε , shifts towards higher temperature with an increase in frequency. The variation of dielectric properties with frequency and temperature shows the dispersion behavior which is explained in the light of Maxwell-Wagner type of interfacial polarization in accordance with the Koop's phenomenological theory. The frequency dependent conductivity results satisfy the Jonscher's power law, σ T (ω) = σ (o) + Aω n , and the results show the occurrence of two types of conduction process at elevated temperature: (i) low frequency conductivity, due to long-range ordering (frequency independent, region I), (ii) mid frequency conductivity at the grain boundaries (region II, dispersion) and (iii) high frequency conductivity at the grain interior due to the short-range hopping mechanism (frequency independent plateau, region III).

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Section: Resultssupporting

confidence: 63%

Frequency and temperature dependent transport properties of NiCuZn ceramic oxide

Hossen

Hossain

2015

Materials Science-Poland

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“…The dielectric dispersion observed in a number of ferrite systems was explained satisfactorily on the basis of the Maxwell-Wagner theory of interfacial polarization [16] in consonance with the Koops phenomenological theory [17,18]. According to this model, it is the conductivity of grain boundaries that contributes more to the dielectric value at lower frequencies.…”

Section: Dielectric Dispersionmentioning

confidence: 58%

Evidence for polaron conduction in nanostructured manganese ferrite

Gopalan¹,

Malini²,

Saravanan³

et al. 2008

J. Phys. D: Appl. Phys.

172

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Nanoparticles of manganese ferrite were prepared by the chemical co-precipitation technique. The dielectric parameters, namely, real and imaginary dielectric permittivity (ε and ε ), ac conductivity (σ ac ) and dielectric loss tangent (tan δ), were measured in the frequency range of 100 kHz-8 MHz at different temperatures. The variations of dielectric dispersion (ε ) and dielectric absorption (ε ) with frequency and temperature were also investigated. The variation of dielectric permittivity with frequency and temperature followed the Maxwell-Wagner model based on interfacial polarization in consonance with Koops phenomenological theory. The dielectric loss tangent and hence ε exhibited a relaxation at certain frequencies and at relatively higher temperatures. The dispersion of dielectric permittivity and broadening of the dielectric absorption suggest the possibility of a distribution of relaxation time and the existence of multiple equilibrium states in manganese ferrite. The activation energy estimated from the dielectric relaxation is found to be high and is characteristic of polaron conduction in the nanosized manganese ferrite. The ac conductivity followed a power law dependence σ ac = Bω n typical of charge transport assisted by a hopping or tunnelling process. The observed minimum in the temperature dependence of the frequency exponent n strongly suggests that tunnelling of the large polarons is the dominant transport process.

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“…As discussed previously, at high temperatures close to 300 C, the data for the wet and dried sample are converging to each other indicating the similarities in both responses and confirm that the initial measurement in the first ramp is a dry-bake cycle. The relaxations related to the molecular nature of the material are associated in the dried sample, which indicated three significant processes; (i) a low temperature relaxation attributed to the local (segmental) molecular motion often called as the Johari-Goldstein ( ) relaxation; [26][27][28] (ii) the glass-transition related loss from cooperative ( ) relaxation at mid-temperatures; 28 (iii) a relaxation related to the conduction losses and Maxwell-Wagner-Sillar (MWS, also known as the interfacial relaxation) [29][30][31][32][33][34][35][36][37][38] at high temperatures. The high temperature process overlaps with the 7, 1750033 (2017) conductive losses because of its nature; it occurs at the interface boundary between constituents in composites.…”

Section: Dielectric Relaxationsmentioning

confidence: 99%

Change in dielectric relaxation with the presence of water in highly filled composites

Tuncer

2017

J. Adv. Dielect.

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It is important to determine the dielectric characteristics of semiconductor encapsulation materials based on epoxy resins. We employed the dielectric spectroscopy technique to investigate the dielectric relaxation in the presence of water and how it changes the relaxation. It was observed that the dielectric relaxation of the material was significantly influenced by absorbed water, the local segmental motion (also known as Johari-Goldstein ( ) relaxation) was influenced most by the presence of the water, it was modified by the wet sample compared to dry one, and required high activation energy. The relaxation related to the glass transition was contributed by the cooperative motion (the -relaxation) of the epoxy resin system. The -relaxation was shifted to a low temperature in the wet sample compared to dry one. The relaxation was modeled with a clear Vogel-Fulcher-Tammann-Hesse (VFTH) behavior; the Vogel temperature of the wet sample was 8 K lower than the dry sample. The presence of water acts as a plasticizer for the molecular relaxation, and speed-up the cooperative process. The measured data were also used to estimate the electrical properties of the resin system by employing an effective-medium model together with a porous media continuum model by taking into account the physical properties of the system. It is already known that the influence of water in semiconductor packaging is important in sensitive applications. The presented measurements and the analysis method would be appreciated within the semiconductor packaging community to improve material selection and performance evaluation efforts.

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Zur Theorie der unvollkommenen Dielektrika

Cited by 1,392 publications

References 8 publications

Frequency and temperature dependent transport properties of NiCuZn ceramic oxide

Frequency and temperature dependent transport properties of NiCuZn ceramic oxide

Evidence for polaron conduction in nanostructured manganese ferrite

Change in dielectric relaxation with the presence of water in highly filled composites

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