A microwave dielectric measurement technique for high permitivity materials

Lanagan, Michael T.; Kim, J. H.; Dube, D. C.; Jang, S. J.; Newnham, R. E.

doi:10.1080/00150198808201341

Cited by 21 publications

(13 citation statements)

References 4 publications

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“…Interactions between the travelling waves and the membrane material affect the magnitude of the transmitted wave, with the ratio of transmitted to incident wave voltage defined as the scattering parameter, S 21 , which is related to the complex permittivity ͓ * ͑͒ = Ј͑͒ − iЉ͔͑͒ of the material. [47][48][49] No analytical expression for * ͑͒ can be obtained, and Ј͑͒ and Љ͑͒ were calculated numerically 48,49 from the measured S 21 . The experimental setup, the measurement and analysis procedures, and the related uncertainties are described in detail elsewhere.…”

Section: B163mentioning

confidence: 99%

State of Water in Perfluorosulfonic Ionomer (Nafion 117) Proton Exchange Membranes

Polizos

Macdonald

et al. 2008

J. Electrochem. Soc.

128

163

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The nature of water in acid-form Nafion 117 was quantified at several hydration levels by dielectric relaxation spectroscopy. Two independent experimental setups were used to collect complex dielectric permittivity spectra at low frequencies ͑0.01 Hz to 1 MHz at −80 to 25°C͒ and in the microwave region ͑0.40-26 GHz at 25-45°C͒. We directly observed the states of water, manifested through three population averages with distinctly resolved dynamical behaviors, and their changes with temperature and hydration level. The fastest process observed was identified as the cooperative picosecond relaxation of free ͑isotropic, bulklike͒ water, whereas the slowest process ͑microsecond relaxation times͒ corresponded to water molecules strongly bound to the charged sulfonic groups. A third type of water was also observed, also characterized by picosecond relaxation times, close to and about three times slower than those of bulk water, which was attributed to loosely bound water and may contain substantial dynamical heterogeneities.

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Section: B163mentioning

confidence: 99%

State of Water in Perfluorosulfonic Ionomer (Nafion 117) Proton Exchange Membranes

Polizos

Macdonald

et al. 2008

J. Electrochem. Soc.

128

163

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“…The measurement technique has been described in elsewhere. 11) Graphite and carbon black powders were measured both in the ranges of X-band frequencies and between 1 and 10 GHz with the coaxial line. However, coal samples were only measured in the X-band frequency range because, as it will be described later, the εr' values of coal powders are very low and independent of frequency.…”

Section: Permittivity Measurementmentioning

confidence: 99%

Complex Permittivity of Graphite, Carbon Black and Coal Powders in the Ranges of X-band Frequencies (8.2 to 12.4 GHz) and between 1 and 10 GHz

et al. 2011

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The real and imaginary parts of the relative complex permittivity (εr' and εr") were measured in the ranges of X-band frequencies (8.2 to 12.4 GHz) and between 1 and 10 GHz for graphite, carbon black and coal powders at room temperature so as to clarify the relation between the complex permittivities of carbonaceous materials and their characteristics, i.e., graphitization, porosity (i.e., specific surface area) and ash contained in coals. It is found that the complex permittivities increase with increasing crystallite size and specific surface area. It is also found that the dependency of the permittivities on the ash content seems be negligible within the range of the ash content in the present study.

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“…Firstly, the measurement uncertainty is very poor for the extreme mismatch of impedance for highdielectric constant materials. T. Lanagan [5] proposed a new method for calculating the complex permittivity by the phase variation of transmittance versus frequency. It is effective for high dielectric constant materials with high loss.…”

Section: Introductionmentioning

confidence: 99%

A Complex Permittivity Measurement Technique for High Dielectric Constant Materials at Microwave Frequency

Xia

Wei

2010

Ferroelectrics

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The measurement uncertainty of traditional transmission/reflection method is very poor for high dielectric constant (>100) materials or sample whose thickness was several integer multiples of half wavelength. A modified calculating procedure was presented for measuring the high dielectric constant materials. The method is based on the thickness resonance when electromagnetic wave is transmitting through transmission line filled with the sample. It is convenient for complex permittivity measurement of high dielectric constant materials with transmission/reflection method.

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A microwave dielectric measurement technique for high permitivity materials

Cited by 21 publications

References 4 publications

State of Water in Perfluorosulfonic Ionomer (Nafion 117) Proton Exchange Membranes

State of Water in Perfluorosulfonic Ionomer (Nafion 117) Proton Exchange Membranes

Complex Permittivity of Graphite, Carbon Black and Coal Powders in the Ranges of X-band Frequencies (8.2 to 12.4 GHz) and between 1 and 10 GHz

A Complex Permittivity Measurement Technique for High Dielectric Constant Materials at Microwave Frequency

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