scholarly journals Effective dielectric permeability and electrical conductivity of polycrystalline PbTe films with disturbed stochiometry

2021 ◽  
Vol 2131 (5) ◽  
pp. 052008
Author(s):  
T Akhmedov ◽  
S M Otazhonov ◽  
M M Khalilov ◽  
N Yunusov ◽  
U Mamadzhanov ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Constant ◽  
Absorption Coefficient ◽  
Dielectric Permeability ◽  
Effective Dielectric Constant ◽  
Wide Range ◽  
Constant E

Abstract This paper presents the study of the effective dielectric constant and electrical conductivity of polycrystalline PbTe films with disturbed stoichiometry. It is shown that superstoichiometric additions of Te and Pb within the limits of solubility by doping with PbTe contribute to a change in a wide range of concentrations of electrically active impurities and, consequently, to an increase in the dielectric constant (ɛ), electrical conductivity (σ) and absorption coefficient (α), in addition, the excess of these components strongly affects the amount of polarization.

scholarly journals Electromagnetic sensor for measuring the dielectric permeability of materials

2020 ◽  
Keyword(s):  
Dielectric Constant ◽  
Experimental Studies ◽  
Dielectric Permeability ◽  
Physical Nature ◽  
Diagnostic Methods ◽  
Effective Dielectric Constant ◽  
Original Design ◽  
Microstrip Resonator ◽  
Electromagnetic Sensor ◽  
Electrophysical Parameters

Relevance: Problems of control and determination of electrophysical parameters of materials of different physical nature are relevant in terms of the development of express methods of analysis of substances in various fields of science and technology, in particular, in biotechnology and biomedicine. Also, the relevance of the work is grounded by the search and implementation of new non-invasive medical diagnostic methods. The purpose of the work is to experimentally test the method of calculating the dielectric constant of multilayer structures based on conformal transformation, to test the method of electromagnetic probing of objects with one-side access using a microstrip resonator. Materials and methods: The paper presents a method for calculating the effective dielectric constant of a three-layer structure using a microstrip resonator of a new shape. A number of solid and liquid materials were investigated experimentally. It is shown that the resonant frequency and quality factor of the resonator loaded with the investigated material allow to estimate the concentration of the components of binary solutions. The possibility of using a microstrip resonator as a plethysmographic sensor has been investigated. Results: An electromagnetic sensor for measuring the dielectric constant of objects with one-side access was developed. The description of the original design of the microstrip resonator is presented and its modeling and experimental research are carried out. The results of measurements of the dielectric constant of objects of different physical nature are obtained: solid dielectrics and biological liquids. The influence of relative glucose concentration on the resonant properties of the sensor was studied. The possibility of using the sensor as a plethysmographic sensor in biomedical systems is shown. Conclusion: Theoretical and experimental studies of a microstrip resonator of complex geometric shape, which are presented in the paper, confirmed the possibility of its use as a sensor of electrophysical parameters of materials with different dielectric constant and conductivity. A new method of blood flow registration is proposed, based on the fixation of changes in the effective dielectric constant of tissues containing blood vessels.

STUDY OF THE INFLUENCE OF DIELECTRIC PERMEABILITY OF THE MATERIAL ON THE RADAR COSS SECTION

2020 ◽  
pp. 98-101
Author(s):  
С.А. Антипов ◽  
А.В. Володько ◽  
Е.А. Ищенко ◽  
В.Н. Кострова ◽  
К.А. Разинкин ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Material ◽  
Dielectric Permeability ◽  
The Body ◽  
Complex Frequency ◽  
Complex Materials ◽  
Modeling Process ◽  
Wide Range ◽  
Object Of Study ◽  
Effective Scattering Surface

В качестве объекта исследования эффективной поверхности рассеяния рассматривается сфера из диэлектрического материала, у которого можно в процессе моделирования изменять диэлектрическую проницаемость среды. Для моделирования был выбран широкий диапазон частот, чтобы можно было отследить влияние отношения длины волны к радиусу сферы, а также смещение максимального значения эффективной площади рассеяния (ЭПР) объекта после изменения диэлектрической проницаемости среды. По полученным результатам было доказано, что невозможно обеспечить низкий уровень ЭПР в очень широкой полосе частот, так как если размер длины волны становится близок с размерами тела, происходит резкий всплеск уровня ЭПР. Также в процессе моделирования было доказано, что повышение диэлектрической проницаемости среды приводит к повышению максимальных значений ЭПР объекта, а также смещение этого пика вниз по частоте. По полученным графикам моностатической ЭПР можно сделать вывод, что применение сложных частотозависимых материалов позволяет добиться значительного снижения эффективной площади рассеяния даже в ситуации, когда объект становится геометрически крупным, то есть сравнимым с длиной волны. Данные сложные материалы применяются в качестве стелс-покрытия In the article, a sphere of dielectric material is considered as an object of study of the effective scattering surface, in which the dielectric constant of the medium can be changed during the simulation. A wide range of frequencies was chosen for modeling so that the influence of the ratio of the wavelength to the radius of the sphere, as well as the shift of the maximum RCS value of the object after changing the dielectric constant of the medium, could be tracked. According to the results, it was proved that it is impossible to provide a low RCS level in a very wide frequency band, since if the wavelength becomes close to the body size, a sharp surge in the RCS level occurs. It was also proved during the modeling process that an increase in the dielectric constant of the medium leads to an increase in the maximum RCS of the object, as well as a shift of this peak down in frequency. According to the obtained graphs of a monostatic RCS, it can be concluded that the use of complex frequency-dependent materials allows one to achieve a significant decrease in the effective scattering area even in a situation when the object becomes geometrically large, that is, comparable to the wavelength. These complex materials are used as a stealth coating

scholarly journals Universal mobility characteristics of graphene originating from charge scattering by ionised impurities

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Jonathan H. Gosling ◽  
Oleg Makarovsky ◽  
Feiran Wang ◽  
Nathan D. Cottam ◽  
Mark T. Greenaway ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Carrier Density ◽  
Carrier Mobility ◽  
Carrier Transport ◽  
Analytical Models ◽  
Pristine Graphene ◽  
High Electron ◽  
Boltzmann Transport ◽  
Transport Parameters ◽  
Wide Range

AbstractPristine graphene and graphene-based heterostructures can exhibit exceptionally high electron mobility if their surface contains few electron-scattering impurities. Mobility directly influences electrical conductivity and its dependence on the carrier density. But linking these key transport parameters remains a challenging task for both theorists and experimentalists. Here, we report numerical and analytical models of carrier transport in graphene, which reveal a universal connection between graphene’s carrier mobility and the variation of its electrical conductivity with carrier density. Our model of graphene conductivity is based on a convolution of carrier density and its uncertainty, which is verified by numerical solution of the Boltzmann transport equation including the effects of charged impurity scattering and optical phonons on the carrier mobility. This model reproduces, explains, and unifies experimental mobility and conductivity data from a wide range of samples and provides a way to predict a priori all key transport parameters of graphene devices. Our results open a route for controlling the transport properties of graphene by doping and for engineering the properties of 2D materials and heterostructures.

scholarly journals Multi-material braids for multifunctional laminates: conductive through-thickness reinforcement

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Caroline O’Keeffe ◽  
Laura Rhian Pickard ◽  
Juan Cao ◽  
Giuliano Allegri ◽  
Ivana K. Partridge ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Carbon Fibre ◽  
Electromagnetic Interference ◽  
Design Tool ◽  
Electrically Conductive ◽  
Current Collection ◽  
Wide Range ◽  
Predictive Design ◽  
The Right ◽  
Metal Wires

AbstractConventional carbon fibre laminates are known to be moderately electrically conductive in-plane, but have a poor through-thickness conductivity. This poses a problem for functionality aspects that are of increasing importance to industry, such as sensing, current collection, inductive/resistive heating, electromagnetic interference (EMI) shielding, etc. This restriction is of course more pronounced for non-conductive composite reinforcements such as glass, organic or natural fibres. Among various solutions to boost through-thickness electrical conductivity, tufting with hybrid micro-braided metal-carbon fibre yarns is one of the most promising. As a well-characterised method of through thickness reinforcement, tufting is easily implementable in a manufacturing environment. The hybridisation of materials in the braid promotes the resilience and integrity of yarns, while integrating metal wires opens up a wide range of multifunctional applications. Many configurations can be produced by varying braid patterns and the constituting yarns/wires. A predictive design tool is therefore necessary to select the right material configuration for the desired functional and structural performance. This paper suggests a fast and robust method for generating finite-element models of the braids, validates the prediction of micro-architecture and electrical conductivity, and demonstrates successful manufacturing of composites enhanced with braided tufts.

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

scholarly journals METAL–INSULATOR TRANSITIONS IN TETRAHEDRAL SEMICONDUCTORS UNDER LATTICE CHANGE

2004 ◽  
Vol 18 (07) ◽  
pp. 975-988
Author(s):  
SHAILESH SHUKLA ◽  
DEEPAK KUMAR ◽  
NITYA NATH SHUKLA ◽  
RAJENDRA PRASAD
Keyword(s):  
Dielectric Constant ◽  
Fermi Surface ◽  
Lattice Constant ◽  
Critical Behavior ◽  
Tight Binding ◽  
Metal Insulator ◽  
Wide Range ◽  
Insulating Phase ◽  
Tetrahedral Semiconductors ◽  
Lattice Compression

Although most insulators are expected to undergo insulator to metal transition on lattice compression, tetrahedral semiconductors Si, GaAs and InSb can become metallic on compression as well as by expansion. We focus on the transition by expansion which is rather peculiar; in all cases the direct gap at Γ point closes on expansion and thereafter a zero-gap state persists over a wide range of lattice constant. The solids become metallic at an expansion of 13% to 15% when an electron Fermi surface around L-point and a hole Fermi surface at Γ-point develop. We provide an understanding of this behavior in terms of arguments based on symmetry and simple tight-binding considerations. We also report results on the critical behavior of conductivity in the metal phase and the static dielectric constant in the insulating phase and find common behavior. We consider the possibility of excitonic phases and distortions which might intervene between insulating and metallic phases.

Contributions to Silicon-Hydrogen Bond-Stretching Frequency in Amorphous Si Alloys

1992 ◽  
Vol 258 ◽  
Author(s):  
Z. Jing ◽  
J. L. Whitten ◽  
G. Lucovsky
Keyword(s):  
Experimental Data ◽  
Hydrogen Bond ◽  
Dielectric Constant ◽  
Ab Initio ◽  
Effective Dielectric Constant ◽  
Bond Energies ◽  
Calculated Frequency ◽  
Bond Stretching ◽  
Amorphous Si ◽  
Good Agreement

ABSTRACTWe have performed ab initio calculations and determined the bond-energies and vibrational frequencies of Si-H groups that are: i) attached to Si-atoms as their immediate, and also more distant neighbors; and ii) attached to three O-atoms as their immediate neighbors, but are connected to an all Si-atom matrix. These arrangements simulate bonding geometries on Si surfaces, and the calculated frequency for i) is in good agreement with that of an Si-H group on an Si surface. To compare these results with a-Si:H alloys it is necessary to take into account an additional factor: the effective dielectric constant of the host. We show how to do this, demonstrating the way results of the ab initio calculations should then be compared with experimental data.

scholarly journals Characterization of percolation behavior in conductor–dielectric 0-3 composites

2014 ◽  
Vol 04 (04) ◽  
pp. 1450035 ◽  
Author(s):  
Lin Zhang ◽  
Patrick Bass ◽  
Zhi-Min Dang ◽  
Z.-Y. Cheng
Keyword(s):  
Dielectric Constant ◽  
Percolation Threshold ◽  
Frequency Dependence ◽  
Experimental Results ◽  
Effective Dielectric Constant ◽  
Filler Concentration ◽  
Percolation Behavior ◽  
The Matrix ◽  
The Relationship

The equation ε eff ∝ (ϕc - ϕ)-s which shows the relationship between effective dielectric constant (εeff) and the filler concentration (φ), is widely used to determine the percolation behavior and obtain parameters, such as percolation threshold φc and the power constant s in conductor–dielectric composites (CDCs). Six different systems of CDCs were used to check the expression by fitting experimental results. It is found that the equation can fit the experimental results at any frequency. However, it is found that the fitting constants do not reflect the real percolation behavior of the composites. It is found that the dielectric constant is strongly dependent on the frequency, which is mainly due to the fact that the frequency dependence of the dielectric constant for the composites close to φc is almost independent of the matrix.

Effects of BST on Optical and Dielectric Properties of Na2O-B2O3-SiO2 Glasses

2016 ◽  
Vol 675-676 ◽  
pp. 335-338
Author(s):  
Pratthana Intawin ◽  
Pichitchai Butnoi ◽  
Wilaiwan Leenakul ◽  
Anocha Munpakdee ◽  
Tawee Tunkasiri ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Transparent Glass ◽  
Optically Transparent ◽  
Constant E ◽  
Enhanced Conductivity ◽  
Quench Method

In this research, the effects of Ba0.7Sr0.3TiO3 (BST) on optical and dielectric properties of Na2O-B2O3-SiO2 glasses were investigated. From the study, the optically transparent glass from BST system was successfully prepared by using melt-quench method. The composition of BST used in this study are ranging between 20-60 wt.% BST. It was found that the addition of BST enhanced conductivity, but in turn reduced the percentage of transmittance in the glasses. The dielectric constant (ɛr) of the BST/Na2O-B2O3-SiO2 glasses improved with increasing the content of BST, which in turn plays an important role in controlling the properties of the BST/Na2O-B2O3-SiO2 glasses.

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