scholarly journals Влияние магнитного поля на диэлектрическую проницаемость композита 80%La-=SUB=-0.7-=/SUB=-Sr-=SUB=-0.3-=/SUB=-MnO-=SUB=-3-=/SUB=-/20%GeO-=SUB=-2-=/SUB=-

2018 ◽  
Vol 60 (1) ◽  
pp. 61
Author(s):  
Ю.В. Кабиров ◽  
В.Г. Гавриляченко ◽  
А.С. Богатин ◽  
Е.И. Ситало ◽  
В.К. Яценко
Keyword(s):  
Magnetic Field ◽  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
Magnetic Fields ◽  
Percolation Threshold ◽  
Room Temperature ◽  
High Conductivity ◽  
Frequency Range ◽  
Two Phase

AbstractThe dielectric properties of a magnetoresistive conducting two-phase 80%La_0.7Sr_0.3MnO_3/20%GeO_2 (wt %) composite have been studied near the percolation threshold in magnetic fields from 0 to 15 kOe at frequencies of the measurement field from 5 kHz to 1 MHz. The samples have inductive impedances; i.e., their permittivities can be considered negative due to a high conductivity in this frequency range. The permittivity increases in magnitude in magnetic field, and the values of the magnetodielectric coefficient reach 23% at room temperature. The reasons for the effect of magnetic field on the dielectric permittivity of samples are discussed.

scholarly journals Смена знака магнитоемкости в парамагнитной области в катион-замещенном селениде марганца

2018 ◽  
Vol 60 (4) ◽  
pp. 670
Author(s):  
С.С. Аплеснин ◽  
М.Н. Ситников ◽  
А.М. Живулько
Keyword(s):  
Magnetic Field ◽  
Solid Solution ◽  
Magnetic Susceptibility ◽  
Dielectric Loss ◽  
Dielectric Permittivity ◽  
Room Temperature ◽  
Frequency Range ◽  
Wagner Model ◽  
Paramagnetic Region ◽  
Orbital Electron

AbstractThe capacity and the dielectric loss tangent of a Gd_ x Mn_1– x Se ( x ≤ 0.2) solid solution have been measured in the frequency range 1–300 kHz without a magnetic field and in a magnetic field of 8 kOe in the temperature range 100–450 K, and the magnetic moment of the solid solution has been measured in a field of 8.6 kOe. The magnetocapacity effect and the change in the magnetocapacity sign have been observed in room temperature in the paramagnetic region. A correlation of the changes in the dielectric permittivity and the magnetic susceptibility with temperature has been revealed. The magnetocapacity is described using the model with orbital electron ordering and the Maxwell–Wagner model.

Dielectric Properties of Eucalyptus urophylla Under an Ultra-Wide Frequency Range

2020 ◽  
Vol 12 (8) ◽  
pp. 1236-1241
Author(s):  
He Xia ◽  
Wang Yong ◽  
Li Yunyan ◽  
Wei Yanqiang ◽  
Quan Peng ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Dielectric Loss ◽  
Dielectric Permittivity ◽  
Loss Factor ◽  
Wide Frequency Range ◽  
Dielectric Loss Factor ◽  
Regression Equations ◽  
Eucalyptus Urophylla ◽  
Frequency Range ◽  
Tangential Directions

Dielectric properties of Eucalyptus urophylla wood were measured by using a network analyzer over an ultrawide frequency range between 0.2 GHz and 20 GHz. The effects of moisture content (MC), temperature and frequency on the dielectric permittivity and the dielectric loss factor of Eucalyptus urophylla were investigated along different grain directions. The results showed that the dielectric permittivity along with the dielectric loss factor increased significantly with the elevation in MC. At the frequency of 2380 MHz with the MC increasing from 0% to 100%, the dielectric permittivity along different grain directions (including longitudinal, radial and tangential directions) increased by 180%, 110% and 112%, respectively, while the loss factor along these three directions increased by 1642%, 3703% and 5058%, respectively. In addition, the increase in dielectric properties of Eucalyptus urophylla wood was determined with the temperature elevating. When the temperature elevated from 20 °C to 140 °C, the dielectric permittivity at 2380 MHz along the longitudinal, radial and tangential directions, increased by 19%, 14% and 15%, respectively, while the loss factor increased by 133% at most. As the radio frequency increased, the dielectric permittivity of wood decreased. Regression equations satisfactorily described the dielectric properties of wood along different grain directions with different moisture contents.

Anisotropic Permittivity Measurement of Layered Inorganic Compounds

2011 ◽  
Vol 492 ◽  
pp. 168-171
Author(s):  
Hong Ya Wu ◽  
Ji Zhou
Keyword(s):  
Dielectric Properties ◽  
Room Temperature ◽  
Inorganic Compounds ◽  
Frequency Range ◽  
Impedance Analyzer ◽  
Anisotropic Dielectric ◽  
Permittivity Measurement

The anisotropic permittivity of fluorophlogopite and biotite was measured as a function of frequency in directions along and perpendicular to the cleavage planes. The measurements were performed using an impedance analyzer in the frequency range between 0.01MHz and 10MHz at room temperature. Micas showed anisotropic dielectric properties and the anisotropy of biotite was stronger than fluorophlogopite. The permittivity reduced with the increase of frequency. These properties depended on the structure, composition and defects of micas.

scholarly journals Dielectric Properties of Ternary ( ) ( )x ( ) x ZnO MgO PO 30 2 5 70− (x = 5, 8, 13) Glasses

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
S. F. Khor ◽  
Z. A. Talib ◽  
W. M. Daud ◽  
H. A. A. Sidek ◽  
W. M. M. Yunus ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
Empirical Data ◽  
Loss Factor ◽  
Low Frequency ◽  
Frequency Range ◽  
Melt Quenching ◽  
Dipolar Relaxation ◽  
Temperature Range

(ZnO)30(MgO)x(P2O5)70-x glasses of the composition x = 5, 8 and 13 mol % have been prepared by melt quenching technique. The dielectric permittivity (89) and loss factor (8:) were measured in the frequency range from 0.01 Hz to 1 MHz and in the temperature range 303 to 573 K . From the results there are evidence of dipolar relaxation occurring between 103 – 106 Hz while at low frequency the spectrum is dominated by dc conduction which manifested by the 1/@ slope of loss factor plot. Value of the relaxing frequency (@p) plotted against 1/T shows one electrical transportation mechanism. The empirical data was sufficiently fitted by using Harviliak-Negami equation.

scholarly journals High field magnetoresistance of nanocomposites (Co84Nb14Ta2)X(Al2O3)100-X near the percolation threshold

2018 ◽  
Vol 185 ◽  
pp. 01013 ◽  
Author(s):  
Mikhail Blinov ◽  
Ivan Zakharchuk ◽  
Erkki Lähderanta ◽  
Alexander Sitnikov ◽  
Igor Rodionov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Percolation Threshold ◽  
Volume Fraction ◽  
Ion Beam ◽  
Experimental Studies ◽  
Magnetic Data ◽  
Tunnel Barrier ◽  
Positive Contribution ◽  
Ion Beam Sputtering

We present results of experimental studies of magnetic properties, resistivity and magnetoresistance (MR) of (Co84Nb14Ta2)x(Al2O3)100-x films deposited onto a glass-ceramic substrate by the ion-beam sputtering, focusing on MR in high magnetic fields for compositions close to the percolation threshold (x=47-57 at.%). The samples consist on Co-Nb-Ta metallic nanogranules size of 2-5 nm which are embedded into the non-stoichiometric Al-O matrix. Magnetization was measured by SQUID magnetometer at T=4.2-350 K. MR was studied in the pulsed magnetic fields μ0H up to 20 T at T=70-300 K in three geometries: magnetic field in plane parallel and perpendicular to current, magnetic field perpendicular to plane. The pulse duration was 11-12 ms. For the sample with x=57 at.% the temperature dependence of conductivity follows the lnT behavior that matches a strong tunnel coupling between nanogranules. With decreasing metal volume fraction lnT behavior gradually changes to the T1/2 dependence at 47 at.%. For all samples MR is small (<1%) and negative. For x<57 at.% it is slightly anisotropic at μ0H<1.0 T and almost saturates with increasing magnetic field. There is an evidence of small positive contribution to MR at μ0H=20T. Accordingly to structural and magnetic data a large amount of metallic atoms are located between magnetic nanogranules that diminish the tunnel barrier height and make tunnel MR small and weakly dependent on temperature.

Dielectric properties of polymer/clay nanocomposites

2020 ◽  
pp. 096739112095325
Author(s):  
Nadeem Anwar ◽  
Muhammad Ishtiaq ◽  
Abdul Shakoor ◽  
Niaz Ahmad Niaz ◽  
Tasneem Zahra Rizvi ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
Polymer Nanocomposites ◽  
Acrylonitrile Butadiene Styrene ◽  
Interfacial Area ◽  
Polymer Chains ◽  
Frequency Range ◽  
Restricted Mobility ◽  
Clay Layers ◽  
Silicate Layers

Intercalated and exfoliated nanocomposites of insulating polymers poly methyl methacrylate and acrylonitrile butadiene styrene with organically modified montmorillonite (OMMT) was prepared by solution casting method. Formation of polymer nanocomposites was confirmed by X-Ray Diffraction. Fourier transform infrared spectroscopy confirmed the interaction between polymers and cations on the surface of OMMT layers. Dielectric properties of these nanocomposites were examined at room temperature in the frequency range of 100 Hz–1 MHz. The findings of dielectric measurements exhibited higher real and imaginary dielectric permittivity values for exfoliated nanocomposites and lesser real and imaginary dielectric permittivity values for intercalated nanocomposites as compared with pure polymers in the same frequency range. The increase in the permittivity values is attributed to Maxwell Wagner polarization in exfoliated nanocomposites because of increased interfacial area between polymer and the clay layers. Decrease in dielectric permittivity in intercalated polymer nanocomposites is attributed to restricted mobility of polymer chains due to nanoscopic confinement of the polymer with the silicate layers.

Spectral Measurements of Dielectric Properties of Polypropylene Films in the Subterahertz Frequency Range

2014 ◽  
Vol 9 (4) ◽  
pp. 15-38
Author(s):  
Sergei Kuznetsov ◽  
Mikhail Astafev ◽  
Pavel Lazorskiy ◽  
Vladislav Sklyarov ◽  
Evgeny Lonshakov ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
Polymeric Films ◽  
Optical Methods ◽  
Spectral Measurements ◽  
Frequency Range ◽  
Phase Measurements ◽  
Fabry Perot ◽  
Polypropylene Films ◽  
Different Thickness

We describe three alternative quasi-optical methods for measuring dielectric properties of low-absorbing polymeric films at subterahertz frequencies using BWO-spectroscopy. For two of them, the dielectric permittivity of a pure film is determined through amplitude-phase measurements when the film is inserted into Mach-Zehnder and Fabry-Perot interferometers. In the third case, the permittivity is retrieved via investigating spectral features of a supplementary resonant metallic structure created on the film’s surface to enhance its dispersive properties. The described methods were applied to measure the dielectric permittivity for polypropylene films of different thickness (from 10 to 512 um) from the GoodFellow company (UK). The experimental data obtained by these three techniques are compared with each other and the analysis of factors explaining discrepancy in the measured values of the dielectric permittivity is presented

Dielectric Properties of Pd/Y8Z Composites

1999 ◽  
Vol 575 ◽  
Author(s):  
Mark G.H.M. Hendriks ◽  
Henk Verwei ◽  
Manon P. Timmerman
Keyword(s):  
Dielectric Properties ◽  
Percolation Threshold ◽  
Double Layer ◽  
Low Temperatures ◽  
Room Temperature ◽  
Electronic Conductivity ◽  
Impedance Measurements ◽  
High Frequencies ◽  
A Value ◽  
Double Layer Capacity

ABSTRACTImpedance measurements are performed on Pd/Y8Z composites. At 500 'C a 2- 108 times enhancement of the permittivity of the composite at a Pd composition near the percolation threshold for electronic conductivity relative to Y8Z at room temperature is obtained. At high frequencies, the enhancement decreases to a value comparable to geometric capacity of the composite as the double-layer capacity diminishes. At relatively low temperatures the capacity of Y8Z, due to ionic polarisability, increases with temperature.

Measurement Of The Dielectric Properties Of Polystyrene Particles In Electrolyte Solution

1996 ◽  
Vol 430 ◽  
Author(s):  
C. Grosse ◽  
M. C. Tirado
Keyword(s):  
Dielectric Properties ◽  
Electrolyte Solution ◽  
Electric Quadrupole ◽  
High Conductivity ◽  
Frequency Range ◽  
Impedance Analyzer ◽  
Micron Size ◽  
Reference Measurements ◽  
Made In

AbstractThe permittivity and conductivity of suspensions of spherical sub micron size polystyrene particles were measured in the 10 kHz to 10 MHz frequency range using a HP 4192A Impedance Analyzer. Due to the high conductivity of the samples (0.1 to 0.6 S/m) every detail of the measurements had to be optimized. For each sample, the instrument was calibrated as an electric quadrupole, by means of short, open, and reference measurements, using for this last a standard electrolyte with a conductivity similar to that of the sample. The results obtained were combined with measurements in the 1 MNHz to 28 GHz range made in Goettingen, Germany, using precisely the same samples. The final spectra cover the broadest frequency range to date for these systems.

MAGNETIC RESONANCES OBSERVED IN THE HIGH-FIELD MAGNETO-OPTICAL ABSORPTION OF THE QUANTUM ISING FERROMAGNET LiHoF4

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3312-3315
Author(s):  
R. S. EDWARDS ◽  
A. NARDUZZO ◽  
E. LYONS ◽  
L. CHILDRESS ◽  
S. J. BLUNDELL ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Fields ◽  
Optical Absorption ◽  
Fast Moving ◽  
High Field ◽  
Frequency Range ◽  
Ising Ferromagnet ◽  
Temperature Range ◽  
Magnetic Resonances

The magneto-optical absorption of the quantum Ising ferromagnet LiHoF4 has been measured in the frequency range 38 to 140 GHz, the temperature range 0.5 to 20 K and magnetic fields of up to 15 T. The sample was studied in two orientations, with the external magnetic field aligned perpendicular or parallel to the uniaxial direction, i.e., along the quantum and classical directions. In each case, several families of resonances are observed, including linear EPR branches and a series of non-linear fast moving resonances. We present this data and propose an interpretation for the origin of these resonances.

Sign in / Sign up

Export Citation Format

Share Document