AN APPARATUS FOR THE MEASUREMENT OF DIELECTRIC CONSTANTS OF ADSORBED GASES AT FREQUENCIES UP TO 100 Mc./Sec.

1955 ◽  
Vol 33 (2) ◽  
pp. 268-278 ◽  
Author(s):  
M. H. Waldman ◽  
R. McIntosh
Keyword(s):  
Sulphur Dioxide ◽  
Experimental Error ◽  
Dielectric Behavior ◽  
Dielectric Constants ◽  
Frequency Range

The design of an apparatus suitable for the measurement of dielectric constants at frequencies up to 106 Mc./sec. is shown. The apparatus was used to measure changes in capacitance with volume adsorbed for the system sulphur dioxide – rutile at about 3.5 °C. and for frequencies of 13, 36, and 106 Mc./sec. The results failed to reveal any dispersion due to the adsorbed matter in this frequency range. The dielectric behavior observed is the same, within experimental error of a few per cent, as that found by Channen and McIntosh for the same system at 3.7 Mc./sec.

DIELECTRIC CONSTANTS OF LIQUID SULPHUR DIOXIDE, ETHYL CHLORIDE, AND ETHYLENE OXIDE

1957 ◽  
Vol 35 (11) ◽  
pp. 1325-1331 ◽  
Author(s):  
J. D. Nickerson ◽  
R. McIntosh
Keyword(s):  
Ethylene Oxide ◽  
Sulphur Dioxide ◽  
Dipole Moments ◽  
Dielectric Constants ◽  
Ethyl Chloride ◽  
Frequency Range ◽  
Liquid Sulphur

Dielectric constants of sulphur dioxide, ethyl chloride, and ethylene oxide have been measured over the frequency range 9 to 92 Mc./second and at temperatures between −35° and +20 °C. Dipole moments computed from the Debye, Onsager, and Kirkwood equations are reported and compared with the moments which are known from measurements on the gaseous substances.

Tuning the Electric Field Response of MOFs by Rotatable Dipolar Linkers

2019 ◽  
Author(s):  
Johannes P. Dürholt ◽  
Babak Farhadi Jahromi ◽  
Rochus Schmid
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Structural Changes ◽  
Dielectric Behavior ◽  
Two Dimensions ◽  
Dielectric Constants ◽  
Electric Response ◽  
Dipole Strength ◽  
Metal Organic ◽  
Dynamics Simulations

Recently the possibility of using electric fields as a further stimulus to trigger structural changes in metal-organic frameworks (MOFs) has been investigated. In general, rotatable groups or other types of mechanical motion can be driven by electric fields. In this study we demonstrate how the electric response of MOFs can be tuned by adding rotatable dipolar linkers, generating a material that exhibits paralectric behavior in two dimensions and dielectric behavior in one dimension. The suitability of four different methods to compute the relative permittivity κ by means of molecular dynamics simulations was validated. The dependency of the permittivity on temperature T and dipole strength μ was determined. It was found that the herein investigated systems exhibit a high degree of tunability and substantially larger dielectric constants as expected for MOFs in general. The temperature dependency of κ obeys the Curie-Weiss law. In addition, the influence of dipolar linkers on the electric field induced breathing behavior was investigated. With increasing dipole moment, lower field strength are required to trigger the contraction. These investigations set the stage for an application of such systems as dielectric sensors, order-disorder ferroelectrics or any scenario where movable dipolar fragments respond to external electric fields.

scholarly journals A hybrid broadband metalens operating at ultraviolet frequencies

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Farhan Ali ◽  
Serap Aksu
Keyword(s):  
Dielectric Material ◽  
Berry Phase ◽  
Uv Light ◽  
Fdtd Method ◽  
Numerical Aperture ◽  
Limited Range ◽  
Unit Cell ◽  
Dielectric Constants ◽  
Phase Method ◽  
Frequency Range

AbstractThe investigation on metalenses have been rapidly developing, aiming to bring compact optical devices with superior properties to the market. Realizing miniature optics at the UV frequency range in particular has been challenging as the available transparent materials have limited range of dielectric constants. In this work we introduce a low absorption loss and low refractive index dielectric material magnesium oxide, MgO, as an ideal candidate for metalenses operating at UV frequencies. We theoretically investigate metalens designs capable of efficient focusing over a broad UV frequency range (200–400 nm). The presented metalenses are composed of sub-wavelength MgO nanoblocks, and characterized according to the geometric Pancharatnam–Berry phase method using FDTD method. The presented broadband metalenses can focus the incident UV light on tight focal spots (182 nm) with high numerical aperture ($$\hbox {NA}\approx 0.8$$ NA ≈ 0.8 ). The polarization conversion efficiency of the metalens unit cell and focusing efficiency of the total metalens are calculated to be as high as 94%, the best value reported in UV range so far. In addition, the metalens unit cell can be hybridized to enable lensing at multiple polarization states. The presented highly efficient MgO metalenses can play a vital role in the development of UV nanophotonic systems and could pave the way towards the world of miniaturization.

Crystallization and dielectric properties of SrO–BaO–Nb2O5–GeO2 tungsten–bronze glass–ceramics

2001 ◽  
Vol 16 (7) ◽  
pp. 2057-2063 ◽  
Author(s):  
Jiin-Jyh Shyu ◽  
Hsin-Wei Peng
Keyword(s):  
Heat Treatment ◽  
Dielectric Properties ◽  
Tungsten Bronze ◽  
Glass Ceramics ◽  
Dielectric Behavior ◽  
Dendritic Morphology ◽  
Dielectric Constants ◽  
Two Stage ◽  
Tetragonal Tungsten Bronze ◽  
Stage Heat Treatment

The crystallization and dielectric properties of SrO–BaO–Nb2O5–GeO2 glass–ceramics were investigated. One- and two-stage heat-treatment methods were used to convert the parent glass to glass–ceramics. Strontium barium niobate (SBN) with a tetragonal tungsten-bronze structure formed as the major crystalline phase. When the crystallizing temperature/time was increased, the secondary crystalline BaGe2O5 phase coexisted with SBN. BaGe2O5 formed as a surface layer grown from the surface into the interior of the sample. The dendritic morphology of SBN crystals was examined. The glass–ceramics crystallized by two-stage heat treatment have higher dielectric constants than those crystallized by one-stage heat treatment. The highest dielectric constant that was obtained in the present glass–ceramics was 320. The glass–ceramics showed relaxor-type dielectric behavior.

scholarly journals Soil Moisture Estimate Uncertainties from the Effect of Soil Texture on Dielectric Semiempirical Models

2020 ◽  
Vol 12 (14) ◽  
pp. 2343
Author(s):  
Jing Liu ◽  
Qinhuo Liu
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Soil Texture ◽  
Dielectric Behavior ◽  
Volumetric Water Content ◽  
Frequency Range ◽  
Dielectric Model ◽  
Texture Effect ◽  
Semi Empirical ◽  
Semiempirical Models

Soil texture has been shown to affect the dielectric behavior of soil over the entire frequency range. Three universally employed dielectric semiempirical models (SEMs), the Dobson model, the Wang–Schmugge model and the Mironov model, as well as a new improved SEM known as the soil semi-empirical mineralogy-related-to-water dielectric model (SSMDM), incorporate a significant soil texture effect in different ways. In this paper, soil moisture estimate uncertainties from the effect of soil texture on these four SEMs are systematically and widely investigated over all soil texture cases at different frequencies between 1.4 and 18 GHz for volumetric water content levels between 0.0 and 0.4 m3/m3 from the perspective of two aspects: soil dielectric model discordance and soil texture discordance. Firstly, the effect of soil texture on these four dielectric SEMs is analyzed. Then, soil moisture estimate uncertainties due to the effect of soil texture are carefully investigated. Finally, the applicability of these SEMs is discussed, which can supply references for their choice. The results show that soil moisture estimate uncertainties are small and satisfy the 4% volumetric water content retrieval requirement in some cases. However, in other cases, it may contribute relatively significant uncertainties to soil moisture estimates and correspond to a difference that exceeds the 4% volumetric water content requirement, with potential for the largest deviations to exceed 0.22 m3/m3.

scholarly journals Sugar Concentration Measurement System Using Radiofrequency Sensor

Sensors ◽  
2019 ◽  
Vol 19 (10) ◽  
pp. 2354
Author(s):  
Gerardo Aguila Rodriguez ◽  
Nayda Patricia Arias Duque ◽  
Blanca Estela Gonzalez Sanchez ◽  
Oscar Osvaldo Sandoval Gonzalez ◽  
Oscar Hernan Giraldo Osorio ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Measurement System ◽  
Ac Conductivity ◽  
Experimental Error ◽  
Sucrose Solution ◽  
Measuring System ◽  
Sugar Solution ◽  
Frequency Range ◽  
Tan Δ ◽  
Radiofrequency Sensor

A sugar solution measurement system was developed based on the dielectric properties of the sucrose molecule. An ac conductivity and tan δ study as a function of the frequency was performed to find the suitable frequency range for the measuring system. The results indicate that it is possible to obtain a better response of the sensor using the frequencies as the maxima peak in tan δ appears. Developed setup for sucrose solution was appropriate to measure in a 0.15 to 1 g/mL range with an experimental error of about 3%. The proposed system improves the measurement time over some other methods.

scholarly journals Determining the Quality Factor of Dielectric Ceramic Mixtures with Dielectric Constants in the Microwave Frequency Range

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Hetuo Chen ◽  
Xuewen Fu ◽  
Qi An ◽  
Bin Tang ◽  
Shuren Zhang ◽  
...  
Keyword(s):  
Quality Factor ◽  
Microwave Frequency ◽  
Dielectric Constants ◽  
Frequency Range ◽  
Dielectric Ceramic

THE TEMPERATURE DEPENDENCE OF APPARENT DIELECTRIC CONSTANTS OF ADSORBATES ON NON-POROUS TITANIUM DIOXIDE

1957 ◽  
Vol 35 (12) ◽  
pp. 1534-1541 ◽  
Author(s):  
S. E. Petrie ◽  
R. McIntosh ◽  
E. W. Channen
Keyword(s):  
Dielectric Constant ◽  
Titanium Dioxide ◽  
Temperature Dependence ◽  
Experimental Error ◽  
Adsorption Process ◽  
Porous Titanium ◽  
Dielectric Constants ◽  
Effect Of Temperature ◽  
Apparent Dielectric Constant

The temperature dependence of the apparent dielectric constants of various adsorbed polar gases on finely divided, non-porous titanium dioxide has been determined. Within the experimental error, the apparent dielectric constant of the material adsorbed in the monolayer is independent of temperature. The effect of temperature on the dielectric constant for gas adsorbed beyond the monolayer depends on the adsorbate. These results have been interpreted as indicating that molecules initially adsorbed are oscillators, while those adsorbed in later stages of the adsorption process may be rotators or oscillators.

The pressure dependence of refractivity of polar gases

1960 ◽  
Vol 255 (1282) ◽  
pp. 427-433 ◽  
Keyword(s):  
Pressure Dependence ◽  
Sulphur Dioxide ◽  
Experimental Error ◽  
Methyl Chloride ◽  
Molecular Polarizability ◽  
Refractive Indices ◽  
Methyl Fluoride ◽  
Carbon Tetrafluoride ◽  
First Order

The refractive indices of several gases have been measured at varying pressures in the range 0 to 50 cm. For carbon tetrafluoride, methyl fluoride and methyl chloride the refractivity varies directly with the density within the limits of experimental error. For ammonia and sulphur dioxide the increase of refractivity with pressure is less than would correspond to the increase in density. This may be interpreted in terms of a negative ‘first-order hyperpolarizability' for the polar vapours, whose molecular polarizability is being decreased by the influence of the field due to neighbouring molecular dipoles.

Microstructure-Electrical Propertyrelationships in Cement-Based Materialss

1994 ◽  
Vol 370 ◽  
Author(s):  
R.A. Olson ◽  
G.M. Moss ◽  
B.J. Christensen ◽  
J.D. Shane ◽  
R.T. Coverdale ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Freezing Point ◽  
Relative Dielectric Constant ◽  
Precise Determination ◽  
Dielectric Behavior ◽  
Dielectric Constants ◽  
Direct Result ◽  
Solvent Exchange ◽  
Early Hydration ◽  
Variable Nature

AbstractThere has been much recent progress on the application of impedance spectroscopy (IS) to the study of microstructure and transport in cement-based materials. The IS spectrum allows for the precise determination of bulk resistance, which is a measure of the pore phase interconnectivity, and calculation of the relative dielectric constant, which is related to the capillary pore size and distribution. High values of the relative dielectric constant (σ105) observed in cement paste at early hydration times are the direct result of the microstructure inducing dielectric amplification. Solvent exchange and freezing experiments, combined with digital-image-based computer modeling, have confirmed the role of large capillary pores in the dielectric amplification in young pastes.The conductivities (σ) and relative dielectric constants (εr) of ordinary portland cement (OPC) pastes were monitored during cooling and solvent exchange with isopropanol and methanol. Dramatic decreases in σ and εr, in some cases over two orders of magnitude, occurred at the initial freezing point of the aqueous phase in the macropores and large capillary pores. The same dramatic decreases in a and er were observed at the onset of solvent exchange. Both effects provide experimental support for the dielectric amplification mechanism within the microstructure on the μm-scale. A secondary dielectric amplification was observed in the frozen and solvent exchanged pastes, which produced dielectric constants on the order of 103. This effect is attributed to amplification on the nm-scale within the layered calcium silicate hydrate (C-S-H) gel microstructure. Additional insight into the variable nature of the C-S-H microstructure was obtained by comparing the dielectric behavior of methanol-exchanged OPC pastes to isopropanolexchanged OPC pastes.

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