Influence of Electrochemically Exfoliated Graphite Addition on the Dielectric Properties of Epoxy/Montmorillonite Nanocomposites

2021 ◽  
Vol 326 ◽  
pp. 3-15
Author(s):  
Adrian Radoń ◽  
Dariusz Łukowiec
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Properties ◽  
High Frequency ◽  
Small Polaron ◽  
Exfoliated Graphite ◽  
Dielectric Losses ◽  
Correlated Barrier Hopping ◽  
Eeg Changes ◽  
Hopping Model ◽  
Temperature Conduction

The influence of hydrophilic electrochemically exfoliated graphite (EEG) and hydrophobic reduced EEG (rEEG) on the electrical conductivity, dielectric properties, and high-frequency dielectric losses of epoxy-based composites with montmorillonite was described. It was confirmed, that the addition of EEG changes the low-temperature conduction mechanism. The electrical conductivity in composite with EEG and montmorillonite was described by correlated barrier hopping model, whereas for composites with montmorillonite and rEEG two models were used: non-overlapping small polaron tunneling and correlated barrier hopping. The addition of EEG drastically changes the activation energy of charge carriers motions from 2.68 to 0.83 eV, whereas the addition of rEEG only to 2.43 eV. Also composite with EEG was characterized by highest high-frequency dielectric losses.

scholarly journals Porous and Nonporous Film-Shaped Magnetorheological Nanocomposites: Dielectric and Electrical Properties

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Aref Naimzad ◽  
Yousef Hojjat ◽  
Mojtaba Ghodsi
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Room Temperature ◽  
Volume Resistivity ◽  
Comparative Investigation ◽  
Dielectric Constants ◽  
Dielectric Losses ◽  
Iron Particles ◽  
Electrical And Dielectric Properties

This paper presents a brief experimental comparative study on electrical and dielectric properties of two sets of porous and nonporous MRNCs, each including five samples of film-shaped magnetorheological nanocomposites (MRNCs) based on room temperature vulcanized (RTV) silicone rubber and nanosized carbonyl iron particles (CIPs). The electrical and dielectric properties of porous and nonporous MRNCs were measured at five different filler concentrations. Several experiments were performed to measure the volume resistivity, dielectric constant, and dielectric loss. The MRNCs dielectric properties were analysed with respect to the parameters like frequency and CIPs loadings. The electrical conductivity was studied in terms of volume resistivity. The comparative investigation suggests the porous MRNCs for smart and light-weighted structures those benefits from a lower electrical property, dielectric losses, and dielectric constants.

Features of frequency dependence of electrical conductivity and dielectric properties in lignins from conifers and deciduous trees

Holzforschung ◽  
2020 ◽  
Vol 74 (12) ◽  
pp. 1113-1122
Author(s):  
Sergey Khviyuzov ◽  
Konstantin Bogolitsyn ◽  
Aleksandr Volkov ◽  
Gennadiy Koposov ◽  
Maria Gusakova
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Properties ◽  
Electric Field ◽  
High Frequency ◽  
Low Frequency ◽  
Adsorbed Water ◽  
Deciduous Trees ◽  
Hydroxyl Groups ◽  
Electrophysical Properties ◽  
Functional Nature

AbstractLignins are among the most common plant polymers and demonstrate pronounced electrical conductivity properties due to their conjugated polymolecular aromatic structure and polyfunctional nature. Electrical conductivity and dielectric properties of lignins from conifers and deciduous trees in the range of electric field frequencies from 10−2 to 107 Hz were investigated by means of dielectric spectroscopy. Characteristic parameters of static and high frequency electrical conductivity were calculated. To study the influence of the lignins functional nature on their electrophysical properties, the study determined three types of relaxators (separate charges or charge systems in the structure of a substance changing their position in space when exposed to an external alternating electric field) in the structure of the lignin macromolecule. Low-frequency relaxators are associated with oscillations of methoxyl groups. Mid-frequency relaxators correspond predominantly to phenolic hydroxyl groups and to hydroxyl groups of adsorbed water. High-frequency relaxators correspond to the hopping of π-electrons along the chain of conjugated bonds of a benzene ring. Differences in the structure and functional nature of lignins from conifers and deciduous trees cause different contributions of low-frequency relaxators. As a result, these features form differences in the electrophysical properties of lignins from conifers and deciduous trees.

scholarly journals Диэлектрические свойства и электропроводность легированного серебром монокристалла TlGaS-=SUB=-2-=/SUB=-

2018 ◽  
Vol 52 (2) ◽  
pp. 167
Author(s):  
С.Н. Мустафаева ◽  
С.М. Асадов ◽  
Э.М. Керимова
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Properties ◽  
Fermi Level ◽  
Single Crystals ◽  
Density Of States ◽  
Frequency Dispersion ◽  
Silver Ions ◽  
Dielectric Losses ◽  
Deep Traps ◽  
Stockbarger Method

AbstractThe effect of silver ions (2 mol %) on the dielectric properties and electrical conductivity of TlGaS_2 single crystals grown by the Bridgman–Stockbarger method is investigated. The experimental results of studying the frequency dispersion of the dielectric coefficients of TlGaS_2 single crystals (2 mol % Ag) makes it possible to establish the nature of dielectric losses and the charge-transfer mechanism, to evaluate the density of states near the Fermi level, the spread of states, the average hopping time and length, and the concentration of deep traps responsible for ac conductivity. The Ag doping of the TlGaS_2 single crystals results in an increase in the density of states near the Fermi level and in a decrease in the average hopping time and length.

scholarly journals Dielectric Characteristics, Electrical Conductivity and Solvation of Ions in Electrolyte Solutions

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5617
Author(s):  
Vladimir V. Shcherbakov ◽  
Yuliya M. Artemkina ◽  
Irina A. Akimova ◽  
Irina M. Artemkina
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Properties ◽  
Aqueous Solutions ◽  
High Frequency ◽  
Electrolyte Solutions ◽  
Effect Of Temperature ◽  
Polar Solvents ◽  
Dielectric Characteristics ◽  
Dissociation Degree ◽  
Temperature Dependences

Solvation and association of ions in solutions largely depend on the dielectric properties of the solvent, the distance between ions in solutions, and temperature. This paper considers the effect of temperature on static dielectric constant (DC), dipole dielectric relaxation (DR) time, and limiting (ultimate) high frequency (HF) electrical conductivity (EC) of water and some polar solvents. In the investigated temperature range (0–370 °C), the static DC and DR time of water decrease, and limiting HF EC passes through a maximum at 250–300 °C with temperature growth. The dielectric characteristics of methanol, ethanol, and propanol behave in a similar way. It is shown that the existence of an HF EC temperature maximum is due to the different nature of the temperature dependences of DC and DR time. It is suggested that the same dependences are responsible for the presence of a maximum in the temperature dependences of the dissociation degree and the ionic product of water. The influence of non-electrolytes concentration as well as metal salts on the dielectric properties of their aqueous solutions is considered. The limiting HF EC of water determines the specific EC value of aqueous electrolyte solutions. Analysis of the absorption of microwave energy by polar solvents, as well as aqueous solutions of non-electrolytes and electrolytes, at a frequency of 2455 MHz is carried out. The optimal conditions for high-frequency heating of solutions have been established. The distance between ions in aqueous solutions of inorganic salts and in non-aqueous solutions of ionic liquids is calculated. It is shown that the maximum on the concentration dependence of the specific EC can be related to ions association.

scholarly journals Sintering, Microstructure, and Dielectric Properties of Copper Borates for High Frequency LTCC Applications

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4017
Author(s):  
Dorota Szwagierczak ◽  
Beata Synkiewicz-Musialska ◽  
Jan Kulawik ◽  
Norbert Pałka
Keyword(s):  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
High Frequency ◽  
Ceramic Materials ◽  
Sintering Behavior ◽  
Terahertz Time Domain Spectroscopy ◽  
Very High Frequency ◽  
X Ray ◽  
Low Dielectric ◽  
Very High

New ceramic materials based on two copper borates, CuB2O4 and Cu3B2O6, were prepared via solid state synthesis and sintering, and characterized as promising candidates for low dielectric permittivity substrates for very high frequency circuits. The sintering behavior, composition, microstructure, and dielectric properties of the ceramics were investigated using a heating microscope, X-ray diffractometry, scanning electron microscopy, energy dispersive spectroscopy, and terahertz time domain spectroscopy. The studies revealed a low dielectric permittivity of 5.1–6.7 and low dielectric loss in the frequency range 0.14–0.7 THz. The copper borate-based materials, owing to a low sintering temperature of 900–960 °C, are suitable for LTCC (low temperature cofired ceramics) applications.

scholarly journals Electrical conductivity and dielectric properties of Sr doped M-type barium hexaferrite BaFe12O19

RSC Advances ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 1531-1542
Author(s):  
Y. Marouani ◽  
J. Massoudi ◽  
M. Noumi ◽  
A. Benali ◽  
E. Dhahri ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Properties ◽  
Barium Hexaferrite

The hexaferrite Ba1−xSrxFe12O19 compounds with x = 0, 0.5 and 1 were synthesized by the autocombustion method.

An impregnation-reduction method to prepare graphite nanosheet/alumina composites and its high-frequency dielectric properties

Rare Metals ◽  
2015 ◽  
Vol 36 (3) ◽  
pp. 205-208 ◽  
Author(s):  
Ke-Lan Yan ◽  
Run-Hua Fan ◽  
Min Chen ◽  
Kai Sun ◽  
Xu-Ai Wang ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
High Frequency ◽  
Reduction Method ◽  
Graphite Nanosheet ◽  
Alumina Composites

Dielectric properties of Shell oil transformer oil with impurities of carbon nanotubes and fullerene C60

2021 ◽  
Vol 24 (04) ◽  
pp. 413-418
Author(s):  
O.V. Kovalchuk ◽  
◽  
I.P. Studenyak ◽  
T.M. Kovalchuk ◽  
E.A. Ayryan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Dielectric Properties ◽  
Fullerene C60 ◽  
Transformer Oil ◽  
C60 Fullerene ◽  
Cooling Efficiency ◽  
Fullerene Concentration ◽  
Multiwall Nanotubes

At the temperature 293 K, the influence of two types of nanoimpurities (carbon multiwall nanotubes and C60 fullerene) both separately and together on the dielectric properties of Shell oil transformer oil has been studied. It has been shown that these impurities do not significantly effect on the value of the dielectric permittivity of Shell oil, but more significantly increase its conductivity. It has been found that in the presence of nanotubes inside Shell oil, the dependence of its electrical conductivity on the fullerene concentration is nonmonotonic. The samples with the fullerene concentration 100 ppm have the highest conductivity. At the fullerene concentration 300 ppm, the conductivity of Shell oil with the impurities of carbon nanotube and C60 fullerene becomes almost equal to the electrical conductivity of Shell oil only with the impurities of carbon nanotubes. It has been suggested that C60 fullerene can be used to reduce the electrical conductivity of Shell oil with magnetic nanoparticles required to increase the cooling efficiency of transformers under the action of their own magnetic field.

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