Observation of Dielectric Peaks in Glassy Se70Te20Sn10 Alloy

2012 ◽  
Vol 329 ◽  
pp. 165-175 ◽  
Author(s):  
A. Sharma ◽  
N. Mehta
Keyword(s):  
Chalcogenide Glasses ◽  
Relaxation Times ◽  
Dielectric Dispersion ◽  
Dielectric Constants ◽  
Audio Frequency ◽  
Frequency Range ◽  
Glass Transition Region ◽  
Dipolar Relaxation ◽  
The Past ◽  
Frequency Dependences

The Temperature and Frequency Dependences of the Dielectric Constants () and Dielectric Loss (") Were Studied in Glassy Se70Te20Sn10Alloy in the Audio-Frequency Range below the Glass Transition Region. the Results Indicated that Dielectric Dispersion Occurred in Glassy Se70Te20Sn10Alloy. Well-Defined Dielectric Peaks Were Obtained in Glassy Se70Te20Sn10Alloy; these Are Rarely Observed in Chalcogenide Glasses. such Loss Peaks Were Not Observed in the Glassy Se80-xTe20SnxSystem in the past for Sn Concentrations of x ≤ 8. A Detailed Analysis of the Data Showed that the Results Could Be Explained in Terms of Dipolar Relaxation, with a Distribution of Relaxation Times, this Is Quite Expected in the Case of Chalcogenide Glasses.

DIELECTRIC PROPERTIES OF POLYVINYL ACETALS

1952 ◽  
Vol 30 (12) ◽  
pp. 940-947 ◽  
Author(s):  
B. L. Funt ◽  
T. H. Sutherland
Keyword(s):  
Dielectric Properties ◽  
Electrical Properties ◽  
Dielectric Relaxation ◽  
Relaxation Times ◽  
Dielectric Dispersion ◽  
Transition Temperatures ◽  
Free Energies ◽  
Frequency Range ◽  
Physical Picture ◽  
Electrical Relaxation

Measurements of dielectric dispersion in vinyl acetal and formal polymers were performed over the frequency range 0.050 to 100 kc. at temperatures between 25 and 135 °C. The results reflect the effects of internal plasticization on the electrical properties of the polymers. With increasing size of the substituent groups from formal to butyral the dispersion range is shifted to lower temperatures at a given frequency. Electrical relaxation times and transition temperatures were obtained and values of enthalpies, free energies, and entropies of activation were calculated. A tentative physical picture of the mechanism of dielectric relaxation in these polymers was also formulated.

scholarly journals DIELECTRIC RELAXATION IN POR-SI LAYERS AT LOW FREQUENCIES

2020 ◽  
pp. 170-179
Author(s):  
Юлия Михайловна Спивак ◽  
Арата Рене Алехандро Кастро ◽  
Мария Павловна Севрюгина ◽  
Мария Александровна Кузнецова ◽  
Вячеслав Алексеевич Мошников
Keyword(s):  
Surface Layer ◽  
Relaxation Times ◽  
Relaxation Mechanism ◽  
Point Of View ◽  
Macroporous Silicon ◽  
Nanostructured Surface ◽  
Frequency Range ◽  
Porous Si ◽  
Low Frequencies ◽  
Frequency Dependences

Методом электрохимического анодного травления получен макропористый кремний с высокоомным мезопористым наноструктурированным «скин»-слоем на поверхности. Измерения частотных зависимостей диэлектрических коэффициентов полученных слоев пористого Si выполнены в частотном интервале 5⋅10 < f < 10 Гц при температуре 295 К и приложенном напряжении 1 В. Выявлен максимум тангенса угла диэлектрических потерь, который, наиболее вероятно, обусловлен преобладанием дипольно-релаксационного механизма поляризации. Обнаружено распределение релаксаторов по временам релаксации, предложена интерпретация полученных результатов с точки зрения строения пористого слоя. Macroporous silicon with a mesoporous nanostructured surface layer on top was obtained by the method of electrochemical anodic etching. The frequency dependences of the dielectric coefficients for porous Si layers were measured in the frequency range 5⋅10 < f < 10 Hz at a temperature of 295 K and an applied voltage of 1 V. A maximum of the dielectric loss tangent is revealed, which is most likely due to the predominance of the dipole relaxation mechanism of polarization. The distribution of relaxers over relaxation times has been. An interpretation of the results obtained from the point of view of the structure of the porous layer is proposed.

scholarly journals Electromagnetic response from multilayer composite coatings based on carbonyl iron, ferroelectrics and MWCNTs at microwave

2019 ◽  
Vol 30 ◽  
pp. 07011
Author(s):  
Grigoriy E. Kuleshov ◽  
Alexey V. Sbrodov ◽  
Tatyana N. Shematilo
Keyword(s):  
Experimental Study ◽  
Composite Materials ◽  
Carbonyl Iron ◽  
Composite Coatings ◽  
Dielectric Constants ◽  
Electromagnetic Response ◽  
Multilayer Composite ◽  
Frequency Range ◽  
Electromagnetic Characteristics ◽  
Frequency Dependences

The electromagnetic characteristics of composite materials based on carbonyl iron, ferroelectrics, and MWCNTs were studied in this article. The complex magnetic and dielectric constants of the experimental samples were measured in the frequency range from 1 GHz to 18 GHz. The results of calculation and the experimental study of the frequency dependences of the reflection coefficient on a multilayer composite coating located on a reflective surface are presented.

Dielectric Relaxation of the Butyl Alcohols in p-Xylene Solution

1971 ◽  
Vol 49 (5) ◽  
pp. 712-718 ◽  
Author(s):  
John Crossley
Keyword(s):  
Dielectric Relaxation ◽  
Relaxation Times ◽  
Alcohol Concentration ◽  
Dielectric Constants ◽  
Pure Liquid ◽  
Frequency Range ◽  
Concentrated Solutions ◽  
Polar Solvents ◽  
Symmetrical Distribution ◽  
Xylene Solution

Dielectric constants and losses of the four butyl alcohols have been measured at concentrations of 0.02–0.12 mol fraction in p-xylene solution over the frequency range 1–35 GHz at 25 °C. The data for the most dilute solutions can be represented by a symmetrical distribution of relaxation times. For the mole concentrated solutions the Cole–Cole plots indicate a separation into two absorption regions and the data can be analyzed in terms of two relaxation times both of which lengthen with increased alcohol concentration. The contribution from the long relaxation time and the apparent dipole moment for each butanol, is independent of alcohol concentration and decreases in the order n-butanol > iso-butanol > sec-butanol > t-butanol. The results are discussed in terms of previous dielectric relaxation studies of pure liquid aliphatic alcohols and their solutions in non-polar solvents.

scholarly journals Магнитная восприимчивость нанокомпозитных редкоземельных титанатов в переменных полях

2020 ◽  
Vol 62 (12) ◽  
pp. 2062
Author(s):  
А.Б. Ринкевич ◽  
Д.В. Перов
Keyword(s):  
Experimental Investigation ◽  
Magnetic Susceptibility ◽  
Rare Earth ◽  
Low Temperatures ◽  
Ac Susceptibility ◽  
Relaxation Times ◽  
Frequency Range ◽  
Debye Formula ◽  
Spherical Voids ◽  
Frequency Dependences

Experimental investigation of magnetic susceptibility of nanocomposite rare earth titanates at low temperatures is carried out in frequency range from 1 Hz to 10 kHz. Nanocomposites based on opal matrices are the objects under study which inter-spherical voids are filled with Gd2Ti2O7, Yb2Ti2O7, Dy2Ti2O7 и Dy2Si2O7 particles sized up to 60 nm. The frequency dependences of AC susceptibility are measured at temperatures from 2 to 20K. At frequencies above 1 kHz the frequency dependence fairly good corresponds to a relaxing oscillator model and can be approximated by Debye formula for all nanocomposites. For frequencies from 1 Hz to 10 kHz, however, it is necessary to apply a model with two relaxation times.

scholarly journals A hybrid broadband metalens operating at ultraviolet frequencies

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Farhan Ali ◽  
Serap Aksu
Keyword(s):  
Dielectric Material ◽  
Berry Phase ◽  
Uv Light ◽  
Fdtd Method ◽  
Numerical Aperture ◽  
Limited Range ◽  
Unit Cell ◽  
Dielectric Constants ◽  
Phase Method ◽  
Frequency Range

AbstractThe investigation on metalenses have been rapidly developing, aiming to bring compact optical devices with superior properties to the market. Realizing miniature optics at the UV frequency range in particular has been challenging as the available transparent materials have limited range of dielectric constants. In this work we introduce a low absorption loss and low refractive index dielectric material magnesium oxide, MgO, as an ideal candidate for metalenses operating at UV frequencies. We theoretically investigate metalens designs capable of efficient focusing over a broad UV frequency range (200–400 nm). The presented metalenses are composed of sub-wavelength MgO nanoblocks, and characterized according to the geometric Pancharatnam–Berry phase method using FDTD method. The presented broadband metalenses can focus the incident UV light on tight focal spots (182 nm) with high numerical aperture ($$\hbox {NA}\approx 0.8$$ NA ≈ 0.8 ). The polarization conversion efficiency of the metalens unit cell and focusing efficiency of the total metalens are calculated to be as high as 94%, the best value reported in UV range so far. In addition, the metalens unit cell can be hybridized to enable lensing at multiple polarization states. The presented highly efficient MgO metalenses can play a vital role in the development of UV nanophotonic systems and could pave the way towards the world of miniaturization.

Dielectric Dispersion and Distribution of the Relaxation Times of the Relaxor Ceramics BBT

2007 ◽  
Vol 353 (1) ◽  
pp. 87-90
Author(s):  
P. Keburis ◽  
J. Banys ◽  
A. Brilingas ◽  
Z. Bortkevic ◽  
A. Kholkin ◽  
...  
Keyword(s):  
Relaxation Times ◽  
Dielectric Dispersion

scholarly journals Dielectric anomalies of solid CO and N2 in the audio frequency range

1999 ◽  
Vol 256 (1) ◽  
pp. 75-80 ◽  
Author(s):  
S. Pilla ◽  
J.A. Hamida ◽  
K.A. Muttalib ◽  
N.S. Sullivan
Keyword(s):  
Audio Frequency ◽  
Frequency Range ◽  
Audio Frequency Range

scholarly journals A note on some further determinations of the dielectric constants of organic bodies and electrolytes at very low temperatures

1898 ◽  
Vol 62 (379-387) ◽  
pp. 250-266 ◽  
Keyword(s):  
Dielectric Constant ◽  
Low Temperatures ◽  
Tuning Fork ◽  
Dielectric Constants ◽  
The Past ◽  
Method Of Measurement ◽  
The Given ◽  
Past Summer

In several previous communications we have described the investigations made by us on the dielectric constants of various frozen organic bodies and electrolytes at very low temperatures. In these researches we employed a method for the measurement of the dielectric constant which consisted in charging and discharging a condenser, having the given body as dielectric, through a galvanometer 120 times in a second by means of a tuning-fork interrupter. During the past summer we have repeated some of these determinations and used a different method of measurement and a rather higher frequency. In the experiments here described we have adopted Nernst’s method for the measurement of dielectric constants, using for this purpose the apparatus as arranged by Dr. Nernst which belongs to the Davy-Faraday Laboratory.

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