scholarly journals Метод моделирования диэлектрической проницаемости анизотропного иерархически построенного нанокомпозита с периодической структурой

2021 ◽  
Vol 47 (16) ◽  
pp. 3
Author(s):  
С.А. Корчагин ◽  
Д.В. Терин
Keyword(s):  
Dielectric Constant ◽  
Electromagnetic Radiation ◽  
Periodic Structure ◽  
High Frequency ◽  
Resonance Absorption ◽  
Complex Dielectric Constant ◽  
Quantum Mechanical ◽  
Equivalent Circuits ◽  
Quantum Mechanical Calculations ◽  
Effective Medium Model

A method is proposed for modeling the complex dielectric constant of an anisotropic hierarchically constructed nanocomposite with a periodic structure, based on the complex application of quantum mechanical calculations, an effective medium model, and equivalent equivalent circuits. The dielectric constant of the TiO2 - Al2O3 nanocomposite under the action of external high-frequency electromagnetic radiation has been investigated. The wavelength ranges at which resonance bursts are observed are determined. The possibility of controlling the maxima of difference losses and resonance absorption maxima by changing the geometric parameters of the nanocomposite is shown.

INVESTIGATION OF COMPLEX INDEX OF REFRACTION OF GALLIUM NITRIDE GaN

2018 ◽  
Vol 14 (2) ◽  
pp. 29-39
Author(s):  
J O AKINLAMI ◽  
I O OLATEJU
Keyword(s):  
Dielectric Constant ◽  
Gallium Nitride ◽  
Photon Energy ◽  
High Frequency ◽  
Index Of Refraction ◽  
Complex Dielectric Constant ◽  
Complex Index ◽  
Maximum Value ◽  
Cell Arrays ◽  
Complex Index Of Refraction

An understanding of the complex index of refraction of Gallium Nitride (GaN) is important because of the increasing application of GaN in many high frequency, optical and electronics devices. Complex index of refraction of Gallium Nitride (GaN)have been investigated theoretically by means of Kramers and Kronig method in the photon energy range 2.0 – 10.0eV. We obtained refractive index which has a maximum value of 2.89 at photon energy 7.0eV, the extinction coefficient which has a maximum value of 1.17 at photon energy 7.0eV, the dielectric constant, the real part of the complex dielectric constant has a maximum value of 7.0 at photon energy 7.0eV and the imaginary part of the complex dielectric constant has a maximum value of 6.79 at photon energy 7.0eV, the transmittance which has a maximum value of 0.18 at photon energy 7.0eV, the absorption coefficient which has a maximum value of 86.18 at photon energy 7.0eV. The values obtained for complex index of refraction ofGaN are essentially important for emerging GaN applications such ashigh-power and high-frequency devices, solar cell arrays for satellites, communications and optoelectronics devices.

scholarly journals Влияние химического состава кристаллов TlIn-=SUB=-1-x-=/SUB=-Er-=SUB=-x-=/SUB=-S-=SUB=-2-=/SUB=- (0≤ x≤0.01) на их диэлектрические характеристики и параметры локализованных состояний

2019 ◽  
Vol 61 (11) ◽  
pp. 2030
Author(s):  
С.Н. Мустафаева ◽  
М.М. Асадов
Keyword(s):  
Dielectric Constant ◽  
Charge Transfer ◽  
Chemical Composition ◽  
High Frequency ◽  
Ac Conductivity ◽  
Relaxation Dispersion ◽  
Complex Dielectric Constant ◽  
High Frequency Range ◽  
Frequency Range ◽  
Frequency Dependences

The frequency dependences of the real (ε) and imaginary (ε ″) components of the complex dielectric constant, tangent of dielectric loss (tan) and ac conductivity (σac) of the obtained TlIn1-хErхS2 (0  x  0.01) crystals have been studied in the frequency range f = 5104–3.5107 Hz. It is established that in TlIn1-хErхS2 a relaxation dispersion of ε and ε″ takes place. The effect of erbium concentration (Er) in TlIn1-хErхS2 crystals on their dielectric coefficients was studied. In the high frequency range, the ac conductivity of TlIn1-хErхS2 crystals obeyed the σac ~ f 0.8 law, which is characteristic of a hopping charge transfer mechanism at states localized near the Fermi level. The parameters of states localized in the band gap and the influence of the chemical composition of the TlIn1-хErхS2 crystals on these parameters are estimated.

Development of a Capacitor Probe to Detect Subsurface Deterioration in Concrete

1997 ◽  
Vol 503 ◽  
Author(s):  
B. K. Diefenderfer ◽  
I. L. Al-Qadi ◽  
J. J. Yoho ◽  
S. M. Riad ◽  
A. Loulizi
Keyword(s):  
Dielectric Constant ◽  
Portland Cement ◽  
Electromagnetic Waves ◽  
Low Cost ◽  
Complex Dielectric Constant ◽  
Life Cycle Costs ◽  
Parallel Plates ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Set Up

ABSTRACTPortland cement concrete (PCC) structures deteriorate with age and need to be maintained or replaced. Early detection of deterioration in PCC (e.g., alkali-silica reaction, freeze/thaw damage, or chloride presence) can lead to significant reductions in maintenance costs. However, it is often too late to perform low-cost preventative maintenance by the time deterioration becomes evident. By developing techniques that would enable civil engineers to evaluate PCC structures and detect deterioration at early stages (without causing further damage), optimization of life-cycle costs of the constructed facility and minimization of disturbance to the facility users can be achieved.Nondestructive evaluation (NDE) methods are potentially one of the most useful techniques ever developed for assessing constructed facilities. They are noninvasive and can be performed rapidly. Portland cement concrete can be nondestructively evaluated by electrically characterizing its complex dielectric constant. The real part of the dielectric constant depicts the velocity of electromagnetic waves in PCC. The imaginary part, termed the “loss factor,” describes the conductivity of PCC and the attenuation of electromagnetic waves.Dielectric properties of PCC have been investigated in a laboratory setting using a parallel plate capacitor operating in the frequency range of 0.1 to 40.1MIHz. This capacitor set-up consists of two horizontal-parallel plates with an adjustable separation for insertion of a dielectric specimen (PCC). While useful in research, this approach is not practical for field implementation. A new capacitor probe has been developed which consists of two plates, located within the same horizontal plane, for placement upon the specimen to be tested. Preliminary results show that this technique is feasible and results are promising; further testing and evaluation is currently underway.

Crystal Forms of Semisynthetic Ergot Alkaloid Terguride

2002 ◽  
Vol 67 (4) ◽  
pp. 479-489 ◽  
Author(s):  
Michal Hušák ◽  
Bohumil Kratochvíl ◽  
Ivana Císařová ◽  
Ladislav Cvak ◽  
Alexandr Jegorov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ergot Alkaloid ◽  
Simplified Model ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
X Ray Diffraction ◽  
Torsion Angles ◽  
Crystal Forms ◽  
X Ray ◽  
Independent Molecules

Two new structures of semisynthetic ergot alkaloid terguride created by unusual number of symmetry-independent molecules were determined by X-ray diffraction methods at 150 K. Form A (monoclinic, P212121, Z = 12) contains three symmetry-independent terguride molecules and two molecules of water in the asymmetric part of the unit cell. The form CA (monoclinic, P21, Z = 8) is an anhydrate remarkable by the presence of four symmetry-independent molecules in the crystal structure. Conformations of twelve symmetry-independent molecules that were found in four already described terguride structures are compared with torsion angles obtained by ab initio quantum-mechanical calculations for the simplified model of N-cyclohexyl-N'-diethylurea.

High-frequency equivalent circuits of junction-gate field-effect transistors

1970 ◽  
Vol 6 (18) ◽  
pp. 590
Author(s):  
P.U. Calzolari ◽  
S. Graffi ◽  
A. Mazzone
Keyword(s):  
High Frequency ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Equivalent Circuits
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