Modeling of Microwave Dielectric Properties of Composites

Tuhkala, Marko; Teirikangas, Merja; Juuti, Jari

doi:10.1002/9781119208549.ch2

Cited by 5 publications

(3 citation statements)

References 60 publications

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“…To this end, we consider the work of Shannon (1993), who derived the dielectric polarizabilities of 61 ions through a least squares refinement technique of dielectric measurements of 129 oxides and 25 fluorides using the Clausius‐Mosotti (CM) equation (Equation ) and the additivity rule of molecular polarizabilities. The additivity rule of molecular polarizabilities (ARMP) is a theory stating that the molecular polarizability of a complex substance can be determined by the additive polarizabilities of fundamental molecular constituents (Blair & Thakkar, 2014; Cygan & Lasaga, 1986; Shannon, 1993; Tuhkala et al., 2017). For some theoretical ions M 2+ , M ′ 4+ , and X 2− and corresponding molecules

{normalM}_{2} {normalM}^{'} {normalX}_{4}

, MX, and M ′ X 2 the ARIP theory states that

α_{normalD} false({normalM}_{2} {normalM}^{'} {normalX}_{4} false) = 2 α_{normalD} false(MX false) + α_{normalD} false({normal M^{'} X}_{2} false) .

…”

Section: Discussionmentioning

confidence: 99%

Modeling the Dielectric Properties of Minerals From Crystals to Bulk Powders for Improved Interpretation of Asteroid Radar Observations

et al. 2020

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Planetary radar has provided a growing number of data sets on the inner planets and near‐Earth and main belt asteroid populations in the solar system. Physical interpretation of radar data for inference of surface properties requires constraints on the constitutive parameters of the material making up a given surface. In this study, the complex permittivity of seven minerals as a function of frequency and porosity is measured using the coaxial transmission line method to determine the mixing equation that best describes the relationship between the real part of the complex permittivity of single mineral crystals and granular mineral powders. We find the Looyenga‐Landau‐Lifshitz and Bruggeman symmetric mixing equations to describe our experimental results with the highest accuracy. The variation in the real part of the permittivity of solid mineral crystals between different minerals is shown to depend on the grain density and the chemical composition of the minerals. These mixing relationships are incorporated into an asteroid radar model and used to calculate the porosity in the near‐surface of seven asteroids visited by robotic spacecraft using Earth‐based radar observations. The results of the asteroid radar model support the presence of significant porosity in the boulders on the surface of asteroid 101955 Bennu. This research highlights the ability of radar to measure the porosity on asteroid surfaces and provides theoretical and experimental justification for the inversion of permittivity to bulk density assumed by the asteroid radar model.

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{normalM}_{2} {normalM}^{'} {normalX}_{4}

, MX, and M ′ X 2 the ARIP theory states that

α_{normalD} false({normalM}_{2} {normalM}^{'} {normalX}_{4} false) = 2 α_{normalD} false(MX false) + α_{normalD} false({normal M^{'} X}_{2} false) .

…”

Section: Discussionmentioning

confidence: 99%

Modeling the Dielectric Properties of Minerals From Crystals to Bulk Powders for Improved Interpretation of Asteroid Radar Observations

et al. 2020

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“…To meet the needs and expectations of the global society, it is important to develop new technologies for the production of low-loss microwave dielectric ceramics to be integrated into microelectronic components and electronic circuits as resonators, antennas, filters, and capacitors (Narang and Bahel, 2010;Sebastian et al, 2015;Sulong et al, 2016;Tuhkala et al, 2017). In addition to intrinsic material properties, the broad application value of low-loss ceramics is strongly influenced by various parameters, such as porosity, particle size, stoichiometry, purity of raw constituents and various processing conditions.…”

Section: Introductionmentioning

confidence: 99%

Dielectric Properties of Upside-Down SrTiO3/Li2MoO4 Composites Fabricated at Room Temperature

et al. 2021

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In this paper, ceramic upside-down lithium molybdate-strontium titanate (LMO-ST) composites fabricated at room temperature are described. Room temperature fabrication (RTF) is a promising alternative to the time- and energy-consuming high-temperature sintering of electroceramics, which involves mixing of the initial phases, molding with a steel dye, pressing, and drying, while in the last two phases the action of densification takes place. The LMO-ST composites are based on a high ratio of filler ST, coupled with the corresponding LMO binder. Part of the binder is admixed to the ceramic particles and additional part is added as a saturated aqueous solution, which crystallizes during pressing and drying, leading to its deposition on the surface of the filler particles. As a result, sufficient binding with 76–84% relative density was achieved. The deeper insight into the method was provided by various processing aspects and corresponding microstructural investigations. The particle size distribution, pressure, pressing time, ultrasonic treatment, drying time and processing conditions were optimized to obtain improved functional properties of the LMO-ST composites. The results of this study with relative permittivity in the range of 65–78 and dielectric loss tangent values of 0.002–0.05 can attract considerable attention for the use of LMO-ST composites in the industry of electroceramics.

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“…To meet the needs and expectations of the global society, it is important to develop new technologies for the production of low-loss microwave dielectric ceramics to be integrated into microelectronic components and electronic circuits as resonators, antennas, filters, and capacitors [1][2][3][4]. In addition to intrinsic material properties, the broad application value of low-loss ceramics is strongly influenced by various parameters, such as porosity, particle size, stoichiometry, purity of raw constituents and various processing conditions.…”

Section: Introductionmentioning

confidence: 99%

Dielectric Properties of Upside-Down SrTiO3Li2MoO4 Composites Fabricated at Room Temperature

Kuzmić¹,

Škapin²,

Nelo³

et al. 2021

Prime Archives in Material Science

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Author Contributions: NK, MS, SŠ and HJ agreed about the research content. HJ and MN conceptualized the experimental method developed by Hanna Kähäri and demonstrated all the knowledge and details to NK. NK, MN and HJ developed the LMO-ST composition and processing conditions. NK, MS, HJ, MN and SŠ conceived the idea and course of the experiments. NK, SŠ synthesized the initial strontium titanate. NK conducted the RTF sample preparation and characterization, along with the optimization of processing parameters. SŠ operated the scanning electron microscope and provided the imaging of the composite samples. SŠ conducted XRD characterization of samples. NK, SŠ, MS analyzed the dielectric measurements, SEM micrographs and other results supporting the findings of the study. Findings were discussed and confirmed from NK, SŠ, MS, HJ, MN. All authors reviewed the manuscript.

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Modeling of Microwave Dielectric Properties of Composites

Cited by 5 publications

References 60 publications

Modeling the Dielectric Properties of Minerals From Crystals to Bulk Powders for Improved Interpretation of Asteroid Radar Observations

Modeling the Dielectric Properties of Minerals From Crystals to Bulk Powders for Improved Interpretation of Asteroid Radar Observations

Dielectric Properties of Upside-Down SrTiO3/Li2MoO4 Composites Fabricated at Room Temperature

Dielectric Properties of Upside-Down SrTiO3Li2MoO4 Composites Fabricated at Room Temperature

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