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.

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.

scholarly journals Dielectric properties of the system: 4-n-pentyloxybenzoic acid– N-(4-n-butyloxybenzylidene)-4᾽-methylaniline

2021 ◽  
Vol 16 (2) ◽  
pp. 138-147
Author(s):  
S. A. Syrbu ◽  
M. S. Fedorov ◽  
E. A. Lapykina ◽  
V. V. Novikov
Keyword(s):  
Crystal Structure ◽  
Electrical Conductivity ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Anisotropy ◽  
Specific Electrical Conductivity ◽  
Conductivity Anisotropy ◽  
Independent Molecules ◽  
System Properties ◽  
The Individual

Objectives. Our aim was to study the dielectric properties of the 4-n-pentyloxybenzoic acid– N-(4-n-butyloxybenzylidene)-4’-methylaniline system and reveal how different concentrations of N-(4-n-butyloxybenzylidene)-4’-methylaniline additives affect the dielectric properties of 4-n-pentyloxybenzoic acid.Methods. System properties were investigated using polarization thermomicroscopy and dielcometry.Results. We found that dielectric anisotropy changes its sign from positive to negative at the transition temperature of the high-temperature nematic subphase to the low-temperature one. The anisotropy of the dielectric constant of N-4-n-butoxybenzylidene-4’-methylaniline has a positive value and increases as to the system approaches the crystalline phase. The crystal structure of the 4-n-pentyloxybenzoic acid contains dimers formed by two independent molecules due to a pair of hydrogen bonds. The crystal structure of N-(4-n-butoxybenzylidene)-4’-methylaniline contains associates formed by orientational interactions of two independent molecules. 4-n-Pentyloxybenzoic acid dimers (270 nm) and associates of N-4-n-butoxybenzylidene-4’- methylaniline (250 nm) proved to have approximately the identical length. Considering the close length values of the structural units of both compounds and the dielectric anisotropy sign, we assume that the N-4-n-butoxybenzylidene-4’-methylaniline associates are incorporated into the supramolecular structure of the 4-n-pentyloxybenzoic acid. The specific electrical conductivity of the compounds under study lies between 10−7 and 10−12 S∙cm−1. The relationship between the specific electrical conductivity anisotropy and the system composition in the nematic phase at the identical reduced temperature, obtained between 100 and 1000 Hz is symbatic. However, the electrical conductivity anisotropy values of the system obtained at 1000 Hz are lower compared to those obtained at 100 Hz. At N-(4-n-butoxybenzylidene)-4’-methylaniline concentrations between 30 and 60 mol %, the electrical conductivity anisotropy values are higher than those of the individual component.Conclusions. A change in the sign of the dielectric constant anisotropy of the 4-n-pentyloxybenzoic acid during nematic subphase transitions was established. We showed that the system has the highest dielectric constant anisotropy value when components have an equal number of moles. Highest electrical conductivity anisotropy values are observed when the concentration of the N-4-n-butoxybenzylidene-4᾽-methylaniline system lies between 30 and 60 mol %. 

scholarly journals Obtaining and Main Dielectric Properties of Ba0.6Pb0.4TiO3/graphene Oxide Composite

2020 ◽  
Author(s):  
Ryszard Skulski ◽  
Dariusz Bochenek ◽  
Dagmara Brzezińska ◽  
Leszek Stobinski ◽  
Przemysław Niemiec ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Graphene Oxide ◽  
Dielectric Properties ◽  
Hysteresis Loops ◽  
Conductivity Measurements ◽  
Oxide Composite ◽  
Plasma Sintering ◽  
Ptcr Effect ◽  
Spark Plasma ◽  
Diffraction Patterns

Abstract In this paper there is described the technology of obtaining and results of investigations of microstructure, XRD, SEM, main dielectric properties, electrical conductivity measurements and P-E hysteresis loops of Ba0.6Pb0.4TiO3/graphene oxide composite (abbr. BPT/GO). In the final step of technology, the samples have been sintered using the Spark Plasma Sintering (SPS) method. Diffraction patterns of BPT/GO composite exhibit lines which can be related with perovskite structure, as well as reveal additional lines that can be derived from the initial component oxides. Investigations of electrical conductivity suggest that the PTCR effect occurs at temperatures up to about 120°C. Dielectric hysteresis loops below 90°C are wide and typical for materials with rather high electrical conductivity. The hysteresis loop obtained at 120°C is more typical for ferroelectrics. The obtained material is interesting, however it is probably possible to find better conditions of obtaining it and/or a better composition.

scholarly journals A.C conductivity and dielectric properties of (PVA/ PEO) blends doped with MWCNTs

2019 ◽  
Vol 14 (30) ◽  
pp. 64-72
Author(s):  
Ahmad A. Hasan
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Properties ◽  
The Other ◽  
Poly Vinyl Alcohol ◽  
Conductivity Measurements ◽  
Frequency Range ◽  
Maximum Value ◽  
Multi Walled Carbon Nanotube ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

A.C electrical conductivity and dielectric properties for poly(vinyl alcohol) (PVA) /poly (ethylene oxide) (PEO) blends undopedand doped with multi-walled carbon nanotube (MWCNTs) withdifferent concentrations (1, and 3 wt %) in the frequency range(25x103 - 5x106 Hz) were investigated. Samples of (PVA/PEO)blends undoped and doped with MWCNTs were prepared usingcasting technique. The electrical conductivity measurements showedthat σA.C is frequency dependent and obey the relation σA.C =Aωs forundoped and doped blends with 1% MWCNTs, while it is frequencyindependent with increases of MWCNTs content to 3%. Theexponent s showed proceeding increase with the increase of PEOratio (≥50%) for undoped blends samples, while s value for dopedblends exhibits to change in different manner, i.e. s increases andreach maximum value at 50/50 PVA/PEO, then decreases forresidual doped blends samples with 1% MWCNTs on the other handthe exponent s decrease and reach minimum value at 50/50PVA/PEO for samples doped with 3% MWCNTs, then return toincrease. The results explained in different terms.

Electrical Conductivity and Dielectric Properties of Se85Te15−x Sb x (x = 0 at.%, 2 at.%, 4 at.%, and 6 at.%) Thin Films

2013 ◽  
Vol 42 (12) ◽  
pp. 3397-3407 ◽  
Author(s):  
N. A. Hegab ◽  
M. Fadel ◽  
I. S. Yahia ◽  
A. M. Salem ◽  
A. S. Farid
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Dielectric Properties
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