Non-Debye relaxation and resonance phenomena in dielectric spectra of CaCu3Ti4O12 family functional ceramic materials

2015 ◽  
Vol 08 (04) ◽  
pp. 1550035 ◽  
Author(s):  
A. V. Turik ◽  
A. S. Bogatin
Keyword(s):  
Experimental Data ◽  
Electric Modulus ◽  
Heterogeneous Systems ◽  
Ceramic Materials ◽  
Negative Permittivity ◽  
Debye Relaxation ◽  
Dielectric Spectra ◽  
Calcium Copper Titanate ◽  
Parallel Resonance ◽  
Infralow Frequency Range

Experimental data on dielectric spectra of calcium copper titanate, CaCu 3 Ti 4 O 12 (CCTO) family functional ceramics have been studied and analyzed. It is shown that there are both non-Debye relaxation and resonance regions in their spectra. An occurrence of a retardation of complex permittivity and a relaxation of electric modulus is established. An average relaxation frequency of the electric modulus is considerably (in some cases several orders of magnitude) larger than the retardation frequency of the permittivity. A parallel connection of the capacity and complex conductivity is used to model and interpret experimental data on a negative permittivity in the infralow frequency range. Computer simulation enables us to reveal that the hopping conductivity, characteristic for disordered heterogeneous systems, is to be taken into account to describe adequately experimental data on passing the real part of the capacity (or permittivity) through zero. We have found a critical frequency at which the parallel resonance would take place.

New model of dielectric strength of Debye relaxation in monohydroxy alcohols

2019 ◽  
Vol 33 (26) ◽  
pp. 1950313
Author(s):  
Li-Na Wang ◽  
Xing-Yu Zhao ◽  
Yi-Neng Huang
Keyword(s):  
Experimental Data ◽  
Exact Solution ◽  
High Temperature ◽  
Ising Model ◽  
Dielectric Spectroscopy ◽  
Dielectric Strength ◽  
Experimental Results ◽  
Debye Relaxation ◽  
New Model ◽  
Model Predictions

The Debye relaxation of dielectric spectroscopy exists extensively in monohydroxy alcohols, and the existing theory of the dielectric strength is obviously inconsistent with the experimental results. In this paper, we propose an Ising model of infinite free-rotating pseudospin chains and get the exact solution of the dielectric strength versus temperature. The model predictions are qualitatively consistent with the experimental results, especially the crossover from the low to the high-temperature Curie–Weiss law. The quantitative comparisons indicate that the model predictions can agree well with the experimental data below 250 K.

Complex Design Method of Ceramic Blades and Metal Disk Connection

2019 ◽  
Author(s):  
Dmitry Sapronov ◽  
Michael Mezencev ◽  
Telman Karimbaev ◽  
Sergey Reznik ◽  
Pavel Prosuntsov
Keyword(s):  
Experimental Data ◽  
Silicon Carbide ◽  
Design Method ◽  
Thermal Contact ◽  
Ceramic Materials ◽  
Thermal Contact Conductance ◽  
Test Pieces ◽  
Complex Design ◽  
Complex Approach ◽  
Metal Disk

Abstract This paper presents a complex approach to designing ceramic blades dovetail joints. Two ceramic materials were considered: diamond reinforced silicon carbide and hot pressed silicon nitride (only in contact testing). The model blades were made from diamond reinforced silicon carbide due to its availability and mature technology. Part 1 describes the models of mechanical and thermal contact and contains experimental data on contact strength and thermal contact conductance. Part 2 investigates the effect of stress concentration and scale factor on the fracture of ceramic test pieces. Part 3 proposes a theoretical-experimental method to estimate friction coefficient in a dovetail joint. We also investigated the character of the ceramic blades fracture during the rotor spin-up. Part 4 deals with automating the design process of the ceramic blades dovetail joints using experimental data.

Correlation between global thermodynamic functions and experimental data in multicomponent heterogeneous systems

2016 ◽  
Vol 94 (2) ◽  
pp. 113-119 ◽  
Author(s):  
Igor Povar ◽  
Oxana Spinu
Keyword(s):  
Experimental Data ◽  
Thermodynamic Functions ◽  
Solid Phase ◽  
Heterogeneous Systems ◽  
Thermodynamic Characteristics ◽  
Alkaline Solutions ◽  
Precipitation Process ◽  
Mutual Transformation ◽  
Homogeneous Solutions ◽  
Different Temperatures

The correlation between global thermodynamic functions and such experimental data, which quantitatively characterize the precipitation–dissolution processes of sparingly soluble compounds, as the degree of precipitation and residual concentrations of the solid-phase components in saturated solutions under real conditions, taking into account the complex formation reactions, has been deducted. The paper intends also to introduce widely formal thermodynamic methods for forecasting the conditions of mutual transformation of solid phases through chemical synthesis by precipitation methods, optimization of coprecipitation methods, fractional precipitation from homogeneous solutions, and separation and analysis of chemical compounds. Within the method of residual concentrations, the thermodynamic parameters of the process of precipitating cadmium ions with potassium decanoate from acid and alkaline solutions for different temperatures were investigated. On the basis of the experimentally determined degree of precipitation and its dependence on temperature, the temperature coefficients and overall thermodynamic characteristics of the precipitation process ([Formula: see text], [Formula: see text], and [Formula: see text]) were determined. The optimum conditions of the investigated process of precipitation have been established.

Giant Piezoelectric and Dielectric Relaxations in Statistical Mixtures

2006 ◽  
Vol 115 ◽  
pp. 209-214
Author(s):  
A.I. Chernobabov ◽  
A.V. Turik ◽  
G.S. Radchenko ◽  
S.A. Turik
Keyword(s):  
Dielectric Permittivity ◽  
Aspect Ratio ◽  
Heterogeneous Systems ◽  
Dielectric Constants ◽  
Dielectric Spectra ◽  
Physical Mechanisms ◽  
Dielectric Relaxations ◽  
First Time

The effective complex piezoelectric and dielectric constants of disordered heterogeneous systems of the type of statistical mixtures with the components in the form of spheroid-shaped particles equally oriented but randomly arranged in space were studied. It has been found for the first time that in such systems there appears a giant piezoelectric enhancement accompanied by a giant relaxation of piezoelectric coefficients and the dielectric permittivity. Piezoelectric and dielectric spectra differ significantly from the Debye ones and are of Davidson-Cole type. The influence of the aspect ratio of spheroids on the effects under consideration was studied. The physical mechanisms responsible for the anomalies in the behavior of piezoelectric coefficients and the dielectric permittivity were considered.

STRETCHED EXPONENTIAL STRUCTURAL RELAXATION OF COMPOSITE MATERIALS INDUCED BY IMPURITIES DESORPTION IN VACUUM

1991 ◽  
Vol 05 (29) ◽  
pp. 1911-1918 ◽  
Author(s):  
G. KANIADAKIS ◽  
E. MIRALDI ◽  
G. FRULLA
Keyword(s):  
Experimental Data ◽  
Composite Materials ◽  
Power Law ◽  
Structural Relaxation ◽  
High Accuracy ◽  
Time Dependent ◽  
Carbon Fibres ◽  
Debye Relaxation ◽  
Exponential Time ◽  
Stretched Exponential

The isothermal desorption of impurities, mainly of water, in epoxy reinforced with carbon fibres, kept in vacuum, induces time dependent dimensional variations that do not follow a simple power law. Assuming that dispersive transfer phenomena support the release of the adsorbed vapour, and consequently a “non-Debye” relaxation process, a new method for analysing the experimental data is presented. High accuracy measurements confirm the stretched exponential time dependence of the shrinkage of the examinated samples.

scholarly journals Alumina Trihydrate Effect on Flashover Voltage of Polyester Insulators by Whale Optimization Algorithm Technique

2021 ◽  
Vol 56 (1) ◽  
Author(s):  
Mohamed H. Ali ◽  
Loai S. Nasrat ◽  
Hanafy M. Ismail
Keyword(s):  
Experimental Data ◽  
Optimization Algorithm ◽  
Ceramic Materials ◽  
Whale Optimization Algorithm ◽  
Polymer Materials ◽  
Filler Concentration ◽  
Whale Optimization ◽  
Flashover Voltage ◽  
Voltage Performance ◽  
Alumina Trihydrate

Ceramic materials are commonly used as outdoor insulators for high-voltage power transmission lines. Presently, these ceramic insulators are replaced by composite polymeric insulators with polyester, especially in rainy areas. Unlike ceramic materials, polymer materials have a shorter life, so fillers are used to improve their physical and chemical properties. This paper aims to improve the flashover voltage performance of polyester loaded with Alumina Trihydrate filler in wet weather condition. Due to the high cost of raw materials (polyester and Alumina Trihydrate filler), the Whale Optimization Algorithm model was used to predict the best concentration of Alumina Trihydrate filler to give the best value of flashover voltage. The model is based on experimental data of flashover voltage measurements. A positive correlation of the calculations from the Whale Optimization Algorithm model with experimental data has been demonstrated. The results showed that the flashover voltage performance of polyester is increased with the increase of Alumina Trihydrate filler concentration. Also, the optimum concentration of Alumina Trihydrate filler and flashover values predicted by the MATLAB Whale Optimization Algorithm are very accurate.

scholarly journals PENGUKURAN NILAI DIELEKTRIK MATERIAL CALCIUM COPPER TITANAT ( CaCu3Ti4O12) MENGGUNAKAN SPEKTROSKOPI IMPEDANSI TERKOMPUTERISASI

2017 ◽  
Vol 6 (1) ◽  
pp. 26
Author(s):  
Widodo Budi Kurniawan
Keyword(s):  
Dielectric Constant ◽  
Impedance Spectroscopy ◽  
Ceramic Materials ◽  
Complex Dielectric Constant ◽  
Frequency Range ◽  
Frequency Dependent ◽  
Calcium Copper Titanate ◽  
Ccto Sample

Telah dilakukan pengukuran tetapan dielektrik kompleks dan besarnya impedansi kapasitor pada material keramik Calcium Copper Titanate dengan struktur material CaCu3Ti4O12 (CCTO) dengan kemurnian 99 % menggunakan metode spektroskopi impedansi terkomputerisasi dalam rentang frekuensi 5 kHz – 120 kHz. Tetapan dielektrik maksimum terukur pada sampel yang disintering dengan suhu 7000C yaitu 745 pada frekuensi 5 kHz dan besarnya impedansi kapasitor maksimum terjadi pada sampel CCTO non sintering yaitu 150434 Ω. Hasil penelitian menunjukkan adanya pengaruh frekuensi terhadap tetapan dielektrik kompleks dan impedansi kapasitor dari material yang diteliti. Kata kunci : spektroskopi impedansi, CaCu3Ti4O12, tetapan dielektrik kompleks dan impedansi kapasitor.   MEASUREMENT OF THE DIELECTRIC CONSTANT CALCIUM COPPER TITANATE (CaCu3Ti4O12) MATERIALS USING COMPUTERIZED IMPEDANCE SPECTROSCOPY  ABSTRACT The measurement of the complex dielectric constant and the magnitude of the capacitor impedances of the ceramic materials Calcium Copper Titanate CaCu3Ti4O12 (CCTO) with purity of 99% has been done by using the method of computerized impedance spectroscopy in the frequency range 5 kHz - 120 kHz. The highest dielectric constant of the material was found to be 745 at 5 kHz in the sample sintered 7000C and the highest impedance of capacitor occured in CCTO sample non sintered that is 150434Ω. The results showed that complex dielectric constant and impedance of the capacitor of the material under study was frequency dependent. Keywords : impedance spectroscopy, CaCu3Ti4O12,complex dielectric constant and impedance of capacitor

scholarly journals Определение коэффициента экстинкции моноксида углерода, адсорбированного на диоксиде титана

2021 ◽  
Vol 129 (11) ◽  
pp. 1400
Author(s):  
К.М. Буланин ◽  
А.Ю. Михелева ◽  
Д.Н. Щепкин ◽  
А.В. Рудакова
Keyword(s):  
Experimental Data ◽  
Carbon Monoxide ◽  
Infrared Spectroscopy ◽  
Extinction Coefficient ◽  
Room Temperature ◽  
Heterogeneous Systems ◽  
Tio2 Anatase ◽  
Weak Adsorption ◽  
Adsorption Of Co ◽  
Logarithmic Law

The adsorption of carbon monoxide on the TiO2 (anatase) surface at room temperature was studied by infrared spectroscopy and volumetry. The experimental data obtained indicate weak adsorption of CO molecules on the exponentially heterogeneous surface. The adsorption heat decreases according to the logarithmic law in the coverage range of 0.002-0.03. The extinction coefficient of adsorbed CO for the heterogeneous CO/TiO2 system is calculated using the Bouguer-Lambert-Beer law with correction for the Lorenz field taken into account. The conditions for the applicability of the Bouguer-Lambert-Beer's law for the study of heterogeneous systems are discussed.

scholarly journals Research on destruction of oil-containing emulsion waste by hard solid demulsinators based on industry waste

2019 ◽  
Vol 138 ◽  
pp. 01020
Author(s):  
Galina Tarasova ◽  
E. Grigoryeva
Keyword(s):  
Experimental Data ◽  
Heat Treatment ◽  
Sugar Industry ◽  
Ceramic Materials ◽  
Oil Sludge ◽  
Practical Application ◽  
Oil Emulsion ◽  
Industry Waste

The article presents experimental data on the destruction of oil-containing emulsion effluents stabilized by solid emulsifiers, that were obtained by heat treatment of ore mining and processing enterprises (GOK) waste and sugar industry. The comparative characteristics on purification of oil emulsion effluents by solid demulsifiers when passing through a filtration layer consisting of solid demulsifiers particles and a layer of sand are given. As well as research into the practical application of oil sludge in the production of lightweight ceramic materials.

scholarly journals Frequency-induced negative magnetic susceptibility in epoxy/magnetite nanocomposites

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Che-Hao Chang ◽  
Shih-Chieh Su ◽  
Tsun-Hsu Chang ◽  
Ching-Ray Chang
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Electromagnetic Field ◽  
Magnetic Susceptibility ◽  
Memory Effect ◽  
Low Frequency ◽  
Magnetization Vector ◽  
Microwave Frequency ◽  
Debye Relaxation ◽  
X Band

AbstractThe epoxy/magnetite nanocomposites express superparamagnetism under a static or low-frequency electromagnetic field. At the microwave frequency, said the X-band, the nanocomposites reveal an unexpected diamagnetism. To explain the intriguing phenomenon, we revisit the Debye relaxation law with the memory effect. The magnetization vector of the magnetite is unable to synchronize with the rapidly changing magnetic field, and it contributes to diamagnetism, a negative magnetic susceptibility for nanoparticles. The model just developed and the fitting result can not only be used to explain the experimental data in the X-band but also can be used to estimate the transition frequency between paramagnetism and diamagnetism.

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