Dielectric mixtures: electrical properties and modeling

Tuncer, Enis; Serdyuk, Yuriy V.; Gubanski, Stanislaw

doi:10.1109/tdei.2002.1038664

Cited by 272 publications

(163 citation statements)

References 343 publications

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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%

“…37,38,[49][50][51] Here, we assume that the electrical properties of the studied composite system (labeled \c") could be represented with a binary mixture approach where two phases are the resin (labeled \r") and inorganic filler particles (labeled \f "). Once we adopt this approach, the electrical properties of the highly filled composite can be expressed with the scaled complex permittivity approach as follows: [50][51][52][53][54][55] ð…”

Section: Dielectric Mixture Approachmentioning

confidence: 99%

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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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Section: Dielectric Relaxationsmentioning

confidence: 99%

Section: Dielectric Mixture Approachmentioning

confidence: 99%

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

Tuncer

2017

J. Adv. Dielect.

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“…In such an approach, the signs of the calculated g in Fig. 2 are used as a pre-distribution for the sign of the polarization distribution in a numerical method based on the constrained least-squares algorithm [6,7,8]. The averaging of g values is performed by considering various bin sizes.…”

Section: Eq (3) Is Written As a Matrix Equationmentioning

confidence: 99%

“…(1). The method * Electronic address: enis.tuncer@physics.org has previously been applied to extract the distribution of relaxation times from dielectric spectroscopy data [6,7] and the spectral density function (distribution) of dielectric mixtures [8]. In those problems, the distributions were probability densities of relaxation times and spectral parameters.…”

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confidence: 99%

Numerical extraction of distributions of space-charge and polarization from laser intensity modulation method

Tuncer

Lang

2005

Applied Physics Letters

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The Fredholm integral equation of the laser intensity modulation method is solved with the application of the Monte Carlo technique and a least-squares solver. The numerical procedure is tested on simulated data. In the LIMM experiment, a thin sample with electrodes on both surfaces is irradiated with a modulated laser. The light is absorbed at the irradiated electrode and the heat diffuses into the sample. Space-charge and polarization in the material respond to a non-uniform temperature distribution, and produce a pyroelectric current density j. The real j r and imaginary j i parts of the current are recorded for each modulation frequency ν. The typical frequency range is between 10 Hz and 100 kHz. Lang [2] and Mellinger [3] have recently illustrated how to reconstruct the space-charge and polarization profiles with polynomial and Tikhonov[4] regularizations, respectively. In this letter, an alternative numerical method is presented and tested.The measured current density in LIMM is expressed as a Fredholm integral equation [2],where g(z) is the unknown distribution of space charge or polarization, T(ν, z) is the solution of one-dimensional heat-conduction equation, z is the coordinate in the thickness direction, and ı = √ −1. The integral in Eq. (1) is evaluated over the samples thickness s. For a free standing film,Here, A is a constant, κ is the thermal conductivity of the sample. β is the complex thermal wave [β = (1 + ı) √ πνD −1 and D is the thermal diffusivity of the material].A numerical method based on the Monte Carlo method have been proposed by Tuncer and Gubański [6] to solve integral equations in the form of Eq. (1). The method * Electronic address: enis.tuncer@physics.org has previously been applied to extract the distribution of relaxation times from dielectric spectroscopy data [6,7] and the spectral density function (distribution) of dielectric mixtures [8]. In those problems, the distributions were probability densities of relaxation times and spectral parameters. Therefore, a constrained least-squares algorithm was implemented which yielded only positive valued outputs. In the present problem, the space-charge and the polarization distributions g can have both positive and negative magnitudes. As a result, we employ a similar numerical procedure as before [6]. However, here a linear least-squares solver is adopted without any a-priori assumptions instead of the constrained leastsquares method.The numerical procedure proposed is as follows, 1. Eq. (1) is written as a summation over some number n of z values for each experimental frequency point ν m (m = 1, . . . , M , M is the number of experimental data points),2. The z n values are preselected randomly from a linear distribution, 0 < z n < s. Eq. (3) is written as a matrix equation,and solved for g. In Eq. (4), T is the m × n 'kernel' matrix, where T = T(ν m , z n ), g is a column vector with length n (g = g n ), and j is a column vector with length m.4. The minimization then yields the desired distribution gSince the problem is ill-conditi...

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“…In particular, we recently showed that the ac electrical properties of Co nanoparticles embedded into a dielectric ZrO 2 matrix display a complex lowfrequency absorption phenomenon 11,12 in the dielectric regime below the percolation threshold for Co that mimics the so-called universal response 13 of disordered dielectric materials, which remains a topic of very active experimental and theoretical researches. [14][15][16][17] In particular, the ac conductivity and permittivity are characterized in disordered dielectric materials by the existence of a transition above a critical value of the angular frequency from a low-frequency dc plateau to a dispersive high-frequency region, where both the conductivity and the permittivity show an anomalous fractional power-law dependence on the angular frequency. 13,17 This dispersive behavior has been observed in a large variety of materials, 14 suggesting that the universal response is an intrinsic property associated with the geometry and actual characteristics of the conduction network rather than the specific mechanisms responsible for the conduction processes and the nature of the atoms constituting those materials.…”

Section: Introductionmentioning

confidence: 99%

ac conductance in granular insulatingCo-ZrO2thin films: A universal response

et al. 2009

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The ac conductance in granular insulating Co-ZrO 2 thin films prepared by pulsed laser deposition is systematically studied as a function of the Co volume content x. An absorption phenomenon at low frequencies that mimics the universal response of disordered dielectric materials is observed in the range of metal content below the Co percolation threshold x p Ϸ 0.35 in the so-called dielectric regime. The temperature and frequency dependences of this absorption phenomenon are successfully analyzed in terms of random competing conduction channels between Co particles through thermally assisted tunneling and capacitive conductance. The ac conductance is well correlated with the nanostructure of the samples obtained by the transmission electron microscopy and perfectly matches the calculated ac response for a random resistor-capacitor network. We also show the occurrence of fractional power-law dependences on the frequency of the ac conductance taking place at very low frequencies as compared to the typical ranges at which dispersive behavior is observed in classicaldisordered dielectric materials.

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Dielectric mixtures: electrical properties and modeling

Cited by 272 publications

References 343 publications

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

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

Numerical extraction of distributions of space-charge and polarization from laser intensity modulation method

ac conductance in granular insulatingCo-ZrO2thin films: A universal response

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