Permittivity of conductor-dielectric heterogeneous mixtures

Lal, K.; Parshad, R.

doi:10.1088/0022-3727/6/15/305

Cited by 26 publications

(17 citation statements)

References 7 publications

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“…Compared to theoretical models and assuming inclusion of spherical particles, the Bruggeman formula (see eq. (7)) models correctly the addition of aluminum in sample 10 [20], where Re e 1 ð Þ denotes the dielectric constant of the host material (here Re e 1 ð Þ ¼ 10) and 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 v 2 is the volume fraction of the inclusion (here the aluminum powder). According to this approach, the dielectric constant of sample 12 is 4.67.…”

Section: Analysis Of the Measurement Results And Techniquesmentioning

confidence: 99%

Static and Dynamic Permittivity Measurement of High Explosives in the W Band to Investigate Shock and Detonation Phenomena

Rougier

Lefrançois

Chuzeville

et al. 2018

Propellants Explo Pyrotec

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Radio interferometry techniques are often used to investigate shock and detonation phenomena thanks to the radio‐transparency of high explosives in the gigahertz frequency band. These techniques require the knowledge of the permittivity of studied explosives. Although the permittivity has been thoroughly studied for many materials, very few data are available at high frequencies (>75 GHz) for high explosives. In this paper, we report static measurement data of the permittivity for various reactive materials using the standard line transmission method between 75 GHz and 110 GHz (W frequency Band), and we present dynamic measurement results at 94 GHz obtained from the so‐called detonation wavefront tracking method. It is shown that the measurement results provided by these two methods are in good agreement. As a consequence, this work validates the detonation wavefront tracking method for the dynamic measurement of high explosives permittivity, and shows that the static experimental results are relevant for shock wave propagation analysis from millimeter‐wave measurement techniques.

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Section: Analysis Of the Measurement Results And Techniquesmentioning

confidence: 99%

Static and Dynamic Permittivity Measurement of High Explosives in the W Band to Investigate Shock and Detonation Phenomena

Rougier

Lefrançois

Chuzeville

et al. 2018

Propellants Explo Pyrotec

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“…Hence, the effective dielectric constant of a 0-3-0 composite can be evaluated, where the second phase is assumed not to have self-connection with itself, that is, no dimensions of connectivity with itself within the composite. Thus, based on Lal and Parshad (1973) Equation 2 reduces to å 0À3 ¼ å 3-dimensional-matrix þ ö Al 3å 3-dimensional-matrix (1 À ö Al ) 2…”

Section: Methodsmentioning

confidence: 99%

Influence of aluminium inclusions on dielectric properties of three-phase PZT–cement–aluminium composites

Banerjee

Cook-Chennault

2014

Advances in Cement Research

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Novel three-phase piezoelectric composites that comprised lead zirconate titanate (PZT), aluminium and Portland cement were fabricated at a low poling voltage of 0 . 6 kV/mm and temperature of 1608C. Aluminium and PZT particles were distributed in a Portland cement matrix, and the dielectric constant, tan ä and strain coefficients were experimentally investigated as a function of inclusion volume fraction. The three-phase piezoelectric composites were found to possess higher piezoelectric strain coefficients, d 33 , than their two-phase counterparts (PZT and Portland cement composites). The highest value of d 33 observed for the three-phase composite was 8 . 1 pC/N for volume fractions of 0 . 7 and 0 . 2 for PZT and aluminium respectively, which was 164% of the value observed for the two-phase composite, at the same PZT volume fraction. An analytical model was used to predict values for the effective dielectric constant of the three-phase composites, and these values compared reasonably well to the empirical data. An investigation of sample degradation as a function of time was performed. Samples showed the highest degree of reduced dielectric performance occurred within two days of data capture, and minimal subsequent reduction in performance after 300 d. Electrical properties of the composites are influenced by the oxidation of aluminium by the alkaline constituents in the cement matrix, distribution of PZT and aluminium within the matrix, particle agglomeration, inclusion size, contact resistance between particles and air voids. The increased dielectric and piezoelectric strain coefficients, demonstrate that these types of materials may be useful in applications such as structural health monitoring and energy harvesting.

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“…The EMT model is based on a Nan formulation that accounts for composites in which inclusions have an ellipsoidal shape . Reasonable agreement with experiment can also be obtained with a Maxwell–Garnett (M‐G) formulation in which the inclusions are treated as spherical particles and ε r is approximated by ε r = ε 0 (1 + 2φ)/(1 − φ), where ε 0 is the permittivity of the carrier medium . These models are based on a dilute suspension approximation in which the effective electrical permittivity of the binary mixture is assumed to only be governed by localized interactions between the fluidic inclusion and matrix material.…”

Section: Lm Dispersionsmentioning

confidence: 99%

Soft Multifunctional Composites and Emulsions with Liquid Metals

2017

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Binary mixtures of liquid metal (LM) or low-melting-point alloy (LMPA) in an elastomeric or fluidic carrier medium can exhibit unique combinations of electrical, thermal, and mechanical properties. This emerging class of soft multifunctional composites have potential applications in wearable computing, bio-inspired robotics, and shape-programmable architectures. The dispersion phase can range from dilute droplets to connected networks that support electrical conductivity. In contrast to deterministically patterned LM microfluidics, LMPA- and LM-embedded elastomer (LMEE) composites are statistically homogenous and exhibit effective bulk properties. Eutectic Ga-In (EGaIn) and Ga-In-Sn (Galinstan) alloys are typically used due to their high conductivity, low viscosity, negligible nontoxicity, and ability to wet to nonmetallic materials. Because they are liquid-phase, these alloys can alter the electrical and thermal properties of the composite while preserving the mechanics of the surrounding medium. For composites with LMPA inclusions (e.g., Field's metal, Pb-based solder), mechanical rigidity can be actively tuned with external heating or electrical activation. This progress report, reviews recent experimental and theoretical studies of this emerging class of soft material architectures and identifies current technical challenges and opportunities for further advancement.

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Permittivity of conductor-dielectric heterogeneous mixtures

Cited by 26 publications

References 7 publications

Static and Dynamic Permittivity Measurement of High Explosives in the W Band to Investigate Shock and Detonation Phenomena

Static and Dynamic Permittivity Measurement of High Explosives in the W Band to Investigate Shock and Detonation Phenomena

Influence of aluminium inclusions on dielectric properties of three-phase PZT–cement–aluminium composites

Soft Multifunctional Composites and Emulsions with Liquid Metals

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