A Maxwell Garnett Model for Dielectric Mixtures Containing Conducting Particles at Optical Frequencies

Koledintseva, Marina Y.; DuBroff, R.E.; Schwartz, Robert W.

doi:10.2528/pier06052601

Cited by 114 publications

(86 citation statements)

References 13 publications

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“…Bruggeman theory enables one to avoid the uncertainty connected to the choice of background medium that is inherent in the Maxwell-Garnett treatment. 53 The Bruggeman model was found to accurately predict the dielectric constants of two-phase dielectric mixtures in a wide range of compositions.…”

Section: Theory and Discussionmentioning

confidence: 99%

“…Various models in the past considered the effective dielectric response of heterogeneous mixtures in terms of permittivity, volume fractions, and geometry of the initial components. [51][52][53] The formulae provided in these reports are based on distinct structure of a mixture; therefore the validity is determined by how closely the models describe the actual structure. In this work, a model for the dielectric response of the NFO-BTO core-shell structure and its variation with applied magnetic field is discussed.…”

Section: Theory and Discussionmentioning

confidence: 99%

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High frequency magneto-dielectric effects in self-assembled ferrite-ferroelectric core-shell nanoparticles

et al. 2014

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Magneto-dielectric effects in self-assembled core-shell nanoparticles of nickel ferrite (NFO) and barium titanate (BTO) have been investigated in the millimeter wave frequencies. The core-shell nano-composites were synthesized by coating 100 nm nickel ferrite and 50 nm barium titanate nanoparticles with complementary coupling groups and allowing them to self-assemble in the presence of a catalyst forming heterogeneous nanocomposites. Magneto-electric (ME) characterization of as-assembled particles has been carried out by measurements of the relative permittivity ɛr as a function of frequency f under an applied static magnetic field H over 16–24 GHz. Measurements show an H-induced decrease in ɛr of 1 to 1.5%. But a giant magneto-dielectric effect with an H-induced change in permittivity as high as 28% is measured under dielectric resonance in the samples. A strong ME coupling was also evident from H-tuning of dielectric resonance in the composites. A theory for the high frequency magneto-dielectric effect has been developed and consists of the following steps. First the Bruggeman model is used to estimate the effective dielectric constant for the shell consisting of the BTO particles and voids considered as spherical air-pores. Then the permittivity for the core and shell is estimated taking into consideration the sample porosity. Finally the H-dependence of the permittivity due to ME interactions is calculated from the free energy considerations. Estimated ɛr vs. H and dielectric resonance frequency vs. H characteristics are in general agreement with the data.

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Section: Theory and Discussionmentioning

confidence: 99%

Section: Theory and Discussionmentioning

confidence: 99%

High frequency magneto-dielectric effects in self-assembled ferrite-ferroelectric core-shell nanoparticles

et al. 2014

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“…These materials allow for high design flexibility, since they can be adapted to achieve complex shapes and ad-hoc strength levels, provide sound and heat isolations, as well as good electromagnetic shielding protection [3][4][5][6][7]. Micro/nano fabrication processes, indeed, allow for making composites of carbon nanotubes, which could be used in various devices, e.g., actuators [8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Homogenized Permittivity of Composites With Aligned Cylindrical Inclusions for Causal Electromagnetic Simulations

Paulis¹,

Nişanci²,

Koledintseva³

et al. 2012

PIER B

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Abstract-The paper gives an analytical transition from the Maxwell Garnett model of a biphasic mixture (dielectric host and dielectric or conducting inclusions) to the parameters of a singleor double-term Debye representation of the material frequency response. The paper is focused on modeling biphasic mixtures containing cylindrical inclusions. This is practically important for engineering electromagnetic absorbing composite materials, for example, containing carbon fibers. The causal Debye representation is important for incorporation of a composite material in numerical electromagnetic codes, especially time-domain techniques, such as the finite-difference time-domain (FDTD) technique. The equations derived in this paper are different for different types of host and inclusion materials. The corresponding cases for the typical combinations of host and inclusion materials are considered, and examples are provided. The difference between the original Maxwell Garnett model and the derived Debye model is quantified for validating the proposed analytical derivation. It is demonstrated that in some cases the derived equivalent Debye model well approximates the frequency characteristics of the homogeneous model based on the MGA, and in some cases there is an exact match between Debye and Maxwell Garnett models.

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“…In our paper [27], it has been shown that the MG formulation can be used at optical frequencies to predict frequency characteristics of composites containing conductive inclusions (nanorods). In [27], several subtle effects, such as the skin effect in conducting inclusions, the Drude frequency dependence of metals, the effect of the mean free path in small-size conducting inclusions, as well as the dimensional resonances in the nanorods, have been taken into account.…”

Section: Introductionmentioning

confidence: 99%

Maxwell Garnett Rule for Dielectric Mixtures With Statistically Distributed Orientations of Inclusions

Koledintseva

DuBroff²,

Schwartz³

2009

PIER

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Abstract-An analytical model of an effective permittivity of a composite taking into account statistically distributed orientations of inclusions in the form of prolate spheroids will be presented. In particular, this paper considers the normal Gaussian distribution for either zenith angle, or azimuth angle, or for both angles describing the orientation of inclusions. The model is an extension of the Maxwell Garnett (MG) mixing rule for multiphase mixtures. The resulting complex permittivity is a tensor in the general case. The formulation presented shows that the parameters of the distribution law for orientation of inclusions affect the frequency characteristics of the composites, and that it is possible to engineer the desirable frequency characteristics, if the distribution law is controlled.

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A Maxwell Garnett Model for Dielectric Mixtures Containing Conducting Particles at Optical Frequencies

Cited by 114 publications

References 13 publications

High frequency magneto-dielectric effects in self-assembled ferrite-ferroelectric core-shell nanoparticles

High frequency magneto-dielectric effects in self-assembled ferrite-ferroelectric core-shell nanoparticles

Homogenized Permittivity of Composites With Aligned Cylindrical Inclusions for Causal Electromagnetic Simulations

Maxwell Garnett Rule for Dielectric Mixtures With Statistically Distributed Orientations of Inclusions

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