scholarly journals Examination of Effective Dielectric Constants of Nonspherical Mixed-Phase Hydrometeors

2013 ◽  
Vol 52 (1) ◽  
pp. 197-212 ◽  
Author(s):  
Liang Liao ◽  
Robert Meneghini
Keyword(s):  
Dielectric Constant ◽  
Phase Particle ◽  
Dielectric Constants ◽  
Mixed Phase ◽  
Effective Dielectric Constant ◽  
Scattering Parameters ◽  
Oblate Spheroids ◽  
Prolate Spheroids ◽  
Homogeneous Particle ◽  
Ice Water

AbstractThe validity of the effective dielectric constant ɛeff for nonspherical mixed-phase particles is tested by comparing the scattering parameters of ice–water mixtures for oblate and prolate spheroids obtained from the conjugate-gradient and fast Fourier transform (CGFFT) numerical scheme with those computed from the T matrix for a homogeneous particle with the derived ɛeff with the same size, shape, and orientation as that of the mixed-phase particle. The accuracy of the effective dielectric constant is evaluated by examining whether the scattering parameters of interest can reproduce those of the direct computations, that is, the CGFFT results. Computations have been run over a range of prolate and oblate spheroids of different axial ratios up to size parameters of 4. It is found that the effective dielectric constant, obtained from realizations of small particles, can be applied to a class of particle types if the fractional water content remains the same. Analysis of the results indicates that the effective dielectric constant approach is useful in computing radar and radiometer polarimetric scattering parameters of nonspherical mixed-phase particles.

Electrical Extraction of The in-Plane Dielectric Constant of Fluorinated Polyimide

1997 ◽  
Vol 476 ◽  
Author(s):  
Alvin L.S. Loke ◽  
Jeffrey T. Wetzel ◽  
John J. Stankus ◽  
S. Simon Wong
Keyword(s):  
Dielectric Constant ◽  
Electric Fields ◽  
Signal Propagation ◽  
Propagation Delay ◽  
Dielectric Constants ◽  
Effective Dielectric Constant ◽  
Fluorinated Polyimide ◽  
Lower Dielectric Constant ◽  
Out Of Plane ◽  
Fringing Fields

AbstractFluorinated polyimide can potentially replace TEOS as an interlevel dielectric in future ULSI interconnect technologies because its lower dielectric constant offers reduced crosstalk, signal propagation delay, and dynamic power dissipation. One issue associated with polyimides is the anisotropy in dielectric constant, where the smaller out-of-plane dielectric constant, typically measured using parallel-plate capacitors, can misleadingly exaggerate the advantage in reducing crosstalk. In this paper, we present a novel electrical technique to estimate the in-plane dielectric constant of DuPont FPI-136M fluorinated polyimide without requiring dielectric gapfill.A blanket FPI-136M film is deposited over interdigitated inlaid Al(0.5%Cu) structures and the crosstalk capacitance is measured. Identical inlaid structures with air and TEOS passivations are also measured for capacitance calibration. Differences in measured capacitances reflect electric fields fringing in the various passivation dielectrics above the inlaid metal. With the known dielectric constants of air and TEOS, the effective dielectric constant of FPI-136M is interpolated to be 2.8. Interconnect simulations confirm that the effective dielectric constant extraction technique is valid and accurate provided that the passivation layer is sufficiently thick to contain the fringing fields.To estimate the in-plane dielectric constant, we use simulations to determine the combination of in-plane and out-of-plane dielectric constants that is equivalent to the extracted effective dielectric constant. With an out-of-plane dielectric constant of 2.6, the in-plane dielectric constant of FPI-136M is estimated to be 3.0. This technique is applicable to other dieletrics.

scholarly journals Recognition of kinetic transient process in corrosion scales of fuel elements by impedance spectroscopy

Paliva ◽  
2021 ◽  
pp. 118-122
Author(s):  
David Dašek ◽  
Petr Roztočil ◽  
Jan Macák
Keyword(s):  
Raman Spectroscopy ◽  
Dielectric Constant ◽  
Impedance Spectroscopy ◽  
Equivalent Circuit ◽  
Tetragonal Phase ◽  
Oxide Thickness ◽  
Dielectric Constants ◽  
Ex Situ ◽  
Effective Dielectric Constant ◽  
Spectroscopy Data

The presented study concerns with the corrosion kinetics of two zirconium alloys: Zr-Nb-Sn-Fe and Zr-Nb-Fe. Alloy samples were pre-exposed at 360 °C in a LiOH solution containing 70 mg/l of lithium ions. Ex-situ electrochemical impedance spectroscopy (EIS) performed in 0.5 M potassium sulphate solution at 25 °C was used to study the properties of the oxide and kinetic transient effect. Evaluation of the impedance spectroscopy data was based on application of a simple equivalent circuit. The setup of the equivalent circuit conformed to Jonscher´s universal law of dielectric response. The analysis of the impedance data was aimed at estimation of non-dispersive capacitance of the oxide formed during the pre-exposure. Effective values of dielectric constant were calculated using the non-dispersive capacitance and the oxide thickness values, calculated from weight gains. For the pre-transient samples relatively higher values of dielectric constants were obtained. Typical pre-transient dielectric constants for Zr-Nb-Sn-Fe alloy ranged between 20–21, while slightly lower values were obtained for Zr-Nb-Fe alloy. In both alloys steep and significant decrease in effective dielectric constant (e_ef = 9–13) was found for the transient samples. The decrease correlated very well with the drop in percentage of tetragonal oxide determined by Raman spectroscopy and corresponded to the increase of the weight gains of the transient samples. Literature data indicate values of dielectric constants for tetragonal zirconium oxide between 38–46, while those for monoclinic oxide are usually presented between 12–22. The evidenced changes in dielectric constants are therefore in agreement with the expected decrease of tetragonal phase fraction in the oxide layer during the transient. In the Zr-Nb-Sn-Fe post-transient samples values of dielectric constant increased again to 18–20, therefore almost to the pre-transient level. This increase was not evidenced with Raman spectroscopy data, which show constant low content of the tetragonal fraction. Possible explanation of this disagreement is the location of the newly formed post-transient tetragonal oxide presumably at the metal/oxide interface. Oxide thickness of the post-transi-ent samples is 4–7 m and the oxide/metal interface is beyond access of the laser beam of Raman spectrometer. We can conclude that using ex-situ EIS, the transient was observable in both alloys; the change in the ratio of monoclinic and tetragonal phase can be evaluated based on the difference of effective dielectric constant of the two phases. The Zr-Nb-Sn-Fe alloy showed the onset of the transient after the 105th day of pre-exposure, but the change in the ratio of the monoclinic and tetragonal phases was less significant than in the Zr-Nb-Fe alloy, in which, however, the transient could be observed only after 147 days of pre-exposure. The resulting values of the effective dielectric constant of oxides correlated well with the percentage of tetragonal oxide determined by Raman spectroscopy and with the results of the weight gain method.

Ferroelectric nanocomposite with high dielectric constants

2002 ◽  
Vol 755 ◽  
Author(s):  
Mai T.N. Pham ◽  
B.A. Boukamp ◽  
H.J.M. Bouwmeester ◽  
D.H.A. Blank
Keyword(s):  
Dielectric Constant ◽  
Electrical Properties ◽  
Ferroelectric Material ◽  
Metallic Phase ◽  
Dielectric Constants ◽  
Effective Dielectric Constant ◽  
X Ray Diffraction ◽  
Non Volatile Memory ◽  
Colloidal Method ◽  
High Dielectric

ABSTRACTComposites between ferroelectric material and a dispersed metal phase are of great interest due to the improvement in dielectric properties for such applications as high capacitance capacitors, non-volatile memory, ect. Using a colloidal method, Pt particles with a size of 3–5 nm were dispersed homogeneously in a PZT (PbZr0.53Ti0.43O3) matrix. No unwanted reaction phase between PZT and Pt during sintering at 1150 °C could be detected by X-ray diffraction. Electrical properties were investigated by impedance spectroscopy measurement. The effective dielectric constant increased remarkably as a power function of Pt volume content and can be described by the percolation theory. At 25 vol.% of Pt the dielectric constant of the composite is 4 times larger than that of pure PZT. The temperature dependence of the electrical properties is also influenced by the metallic phase fraction.

Electrohydrodynamic deformation and bursts of liquid drops

1971 ◽  
Vol 269 (1198) ◽  
pp. 295-319 ◽  
Keyword(s):  
Electric Fields ◽  
High Field ◽  
Critical Frequency ◽  
Immiscible Liquid ◽  
Dielectric Constants ◽  
Liquid Drops ◽  
Oblate Spheroids ◽  
Prolate Spheroids ◽  
Hydrodynamic Stresses ◽  
Field Strengths

In 60 Hz electric fields, liquid drops suspended in a second immiscible liquid deformed into prolate spheroids oriented in the direction of the field in 22 drop/medium combinations studied experimentally. In steady fields, oblate or prolate spheroids were formed depending upon the dielectric constants and resistivities of the drop and medium. In systems yielding oblate spheroids, a critical frequency existed at which the drop remained spherical at all field strengths. Electrohydrodynamic streaming near the surface of the drop occurred as predicted by Taylor. A theory, valid for both steady and alternating fields, was developed which predicts the conditions leading to oblate and prolate spheroids and which reduces to Taylor’s equations for conducting dielectrics in steady fields and to the equations for perfect dielectrics in steady and alternating fields. The theory explains the general types of deformation and electrohydrodynamic flow which were observed and predicts several interesting new modes of behaviour. In most cases the measured deformations were greater than calculated from the theory; various explanations for this discrepancy are advanced, but no definite conclusions are reached. At high field strengths the drops burst in two basically different ways which we have designated as electric and electrohydrodynamic burst, the first caused by electric stresses alone and the second by a combination of electric and hydrodynamic stresses.

Particle behaviour in shear and electric fields I. Deformation and burst of fluid drops

1962 ◽  
Vol 267 (1328) ◽  
pp. 45-61 ◽  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Quantitative Agreement ◽  
Dielectric Constants ◽  
Liquid Drops ◽  
Electrical Fields ◽  
Oblate Spheroids ◽  
Prolate Spheroids ◽  
Combined Action ◽  
Liquid Dielectrics

The deformation and burst of liquid drops suspended in liquid dielectrics in an electric field were measured. At low electrical fields, the deformation of conducting drops into prolate spheroids showed good quantitative agreement with theoretical equations based on electrostatic theory. Dielectric drops exhibited appreciable deviation from the theory, especially in a number of system s w hen oblate spheroids were formed. The mode of electrical burst was found to show considerable variation with the electrical properties of the systems. The deformation, orientation and burst under the combined action of shear and electric fields were also studied and found to agree with a theory based upon a superposition of electric- and shear-deformation forces. The mode of break-up was found to depend on the ratio of the velocity gradient to the electric field strength, on the interfacial tension, and on the ratios of dielectric constants and of viscosities of the two liquids.

scholarly journals Prospects for the Development of High Energy Density Dielectric Capacitors

2021 ◽  
Vol 11 (17) ◽  
pp. 8063
Author(s):  
Andrew Burke
Keyword(s):  
Dielectric Constant ◽  
Energy Density ◽  
Breakdown Strength ◽  
High Energy ◽  
Dielectric Constants ◽  
Polymer Materials ◽  
High Energy Density ◽  
Effective Dielectric Constant ◽  
High Dielectric ◽  
Very High

In this paper, the design of high energy density dielectric capacitors for energy storage in vehicle, industrial, and electric utility applications have been considered in detail. The performance of these devices depends primarily on the dielectric constant and breakdown strength characteristics of the dielectric material used. A review of the literature on composite polymer materials to assess their present dielectric constants and the various approaches being pursued to increase energy density found that there are many papers in which materials having dielectric constants of 20–50 were reported, but only a few showing materials with very high dielectric constants of 500 and greater. The very high dielectric constants were usually achieved with nanoscale metallic or carbon particles embedded in a host polymer and the maximum dielectric constant occurred near the percolation threshold particle loading. In this study, an analytical method to calculate the dielectric constant of composite dielectric polymers with various types of nanoparticles embedded is presented. The method was applied using an Excel spreadsheet to calculate the characteristics of spiral wound battery cells using various composite polymers with embedded particles. The calculated energy densities were strong functions of the size of the particles and thickness of the dielectric layer in the cell. For a 1000 V cell, an energy density of 100–200 Wh/kg was calculated for 3–5 nm particles and 3–5 µ thick dielectric layers. The results of this study indicate that dielectric materials with an effective dielectric constant of 500–1000 are needed to develop dielectric capacitor cells with battery-like energy density. The breakdown strength would be 300–400 V/µ in a reverse sandwich multilayer dielectric arrangement. The leakage current of the cell would be determined from appropriate DC testing. These high energy density dielectric capacitors are very different from electrochemical capacitors that utilize conducting polymers and liquid electrolytes and are constructed much like batteries. The dielectric capacitors have a very high cell voltage and are constructed like conventional ceramic capacitors.

Air Bridge Technology: A Comparison of Novel Interconnect Materials and Integration Schemes for Beyond 45 nm

2003 ◽  
Vol 766 ◽  
Author(s):  
Kenneth Foster ◽  
Joost Waeterloos ◽  
Don Frye ◽  
Steve Froelicher ◽  
Mike Mills
Keyword(s):  
Dielectric Constants ◽  
Advanced Technology ◽  
Effective Dielectric Constant ◽  
Device Performance ◽  
Interlayer Dielectric ◽  
Integration Schemes ◽  
Stepwise Reduction ◽  
Bridge Technology ◽  
Integrated Device ◽  
Compare And Contrast

AbstractThe electronics industry, in a continual drive for improved integrated device performance, is seeking increasingly lower dielectric constants (k) of the insulators that are used as interlayer dielectric (ILD) for advanced logic interconnects. As the industry continually seeks a stepwise reduction of the “effective” dielectric constant (keff), simple extendibility, leads to the consideration of the highest performance possible, namely air bridge technology. In this paper we will discuss requirements, integration schemes and properties for a novel class of materials that has been developed as part of an advanced technology probe into air bridge architecture. We will compare and contrast these potential technology offerings with other existing dense and porous ILD integration options, and show that the choice is neither trivial nor obvious.

scholarly journals Comment on “investigation of dielectric constants of water in a nano-confined pore” by H. Zhu, F. Yang, Y. Zhu, A. Li, W. He, J. Huang and G. Li, RSC Adv., 2020, 10, 8628

RSC Advances ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 5179-5181
Author(s):  
Sayantan Mondal ◽  
Biman Bagchi
Keyword(s):  
Dielectric Constant ◽  
Dielectric Constants ◽  
Static Dielectric Constant ◽  
Inherent Anisotropy ◽  
Nanoconfined Water

Neglects of inherent anisotropy and distinct dielectric boundaries may lead to completely erroneous results. We demonstrate that such mistakes can give rise to gross underestimation of the static dielectric constant of cylindrically nanoconfined water.

Measurement of effective dielectric constant : A comparison

2011 ◽  
Author(s):  
Aakashdeep ◽  
Saurav Kr. Basu ◽  
G. V. Ujjwal ◽  
Sakshi Kumari ◽  
V. R. Gupta
Keyword(s):  
Dielectric Constant ◽  
Effective Dielectric Constant

DIELECTRIC CONSTANT AND SEEBECK COEFFICIENT FOR SEMICONDUCTORS: THERMODYNAMIC AND DFT STUDIES

2013 ◽  
Vol 12 (06) ◽  
pp. 1350057 ◽  
Author(s):  
HSIU-YA TASI ◽  
CHAOYUAN ZHU
Keyword(s):  
Boundary Condition ◽  
Dielectric Constant ◽  
Seebeck Coefficient ◽  
Gas Phase ◽  
Present Method ◽  
Dielectric Constants ◽  
Semiconductor Materials ◽  
Electronic Polarizability ◽  
Seebeck Coefficients ◽  
Good Agreement

Dielectric constants and Seebeck coefficients for semiconductor materials are studied by thermodynamic method plus ab initio quantum density functional theory (DFT). A single molecule which is formed in semiconductor material is treated in gas phase with molecular boundary condition and then electronic polarizability is directly calculated through Mulliken and atomic polar tensor (APT) density charges in the presence of the external electric field. This electronic polarizability can be converted to dielectric constant for solid material through the Clausius–Mossotti formula. Seebeck coefficient is first simulated in gas phase by thermodynamic method and then its value divided by its dielectric constant is regarded as Seebeck coefficient for solid materials. Furthermore, unit cell of semiconductor material is calculated with periodic boundary condition and its solid structure properties such as lattice constant and band gap are obtained. In this way, proper DFT function and basis set are selected to simulate electronic polarizability directly and Seebeck coefficient through chemical potential. Three semiconductor materials Mg 2 Si , β- FeSi 2 and SiGe are extensively tested by DFT method with B3LYP, BLYP and M05 functionals, and dielectric constants simulated by the present method are in good agreement with experimental values. Seebeck coefficients simulated by the present method are in reasonable good agreement with experiments and temperature dependence of Seebeck coefficients basically follows experimental results as well. The present method works much better than the conventional energy band structure theory for Seebeck coefficients of three semiconductors mentioned above. Simulation with periodic boundary condition can be generalized directly to treat with doped semiconductor in near future.

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