scholarly journals Low Frequency Characteristics of TiO2(Rutile)–Glass Thick Films

1977 ◽  
Vol 4 (1) ◽  
pp. 1-7 ◽  
Author(s):  
B. Licznerski ◽  
K. Nitsch ◽  
B. Rzasa
Keyword(s):  
Relaxation Time ◽  
Dielectric Relaxation ◽  
Low Frequency ◽  
Frequency Characteristics ◽  
Electric Permittivity ◽  
Frequency Range ◽  
Ambient Conditions ◽  
Amorphous Glass ◽  
Tio2 Rutile ◽  
Normal Ambient

An analysis is made of the low-frequency characteristics of the permittivityε′and of tanδof a thick-film insulator containing rutile grains bonded with an amorphous glass. The appearance of dielectric relaxation associated with a maximum of tanδ, as well as characteristic Debye dispersions of the electric permittivity is observed. The relaxation time does not depend on the rutile concentration in the dielectric. An equivalent circuit describing the behaviour of a capacitor with such an insulator in the low frequency range is suggested. The experimental results are shown to be consistent with an analysis based on the assumption that a titanium ion relaxation process occurs in the rutile grains. In normal ambient conditions the influence of this kind of polarization disappears at frequencies higher than 102Hz;ε′and tanδthen change insignificantly and the value of tanδis conditioned by the hopping mechanism of conductivity in the glass and in rutile.

scholarly journals Modification ofS. cerevisiaeGrowth Dynamics Using Low Frequency Electromagnetic Fields in the 1-2 kHz Range

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Ján Barabáš ◽  
Roman Radil ◽  
Ivona Malíková
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Electromagnetic Fields ◽  
Proliferative Response ◽  
Low Frequency ◽  
Growth Dynamics ◽  
Magnetic Flux Density ◽  
Wild Type ◽  
Frequency Range ◽  
Ambient Conditions ◽  
Resonance Theory

This paper details our further experiments pertaining to the influence of low frequency electromagnetic fields (LF EMF) on the growth dynamics of two wild-typeSaccharomyces cerevisiaestrands. We opted to explore frequencies beyond the usual 50–60 Hz range, motivated by the ion parametric resonance theory and several studies which discovered and recorded endogenous biosignals in variousSaccharomyces cerevisiaestrands in the 0.4–2.0 kHz frequency range, most probably stemming from microtubules. Both yeast strands used in our experiments have been subjected to continuous 66-hour session of LF EMF exposure (frequencies 1.2, 1.4, 1.6, 1.8, and 2.0 kHz; average magnetic flux density 2.43 mT) under identical ambient conditions. Experiment results indicate a frequency-dependent proliferative response of both yeast strands.

Study of the Molecular Mobility of Polysaccharide Solid Thin Layers by Dielectric Relaxation Spectroscopy

1997 ◽  
Vol 500 ◽  
Author(s):  
K. Liedermann ◽  
L. Lapčík ◽  
S. Desmedt
Keyword(s):  
Dielectric Relaxation ◽  
Low Frequency ◽  
Thin Layers ◽  
Side Chain ◽  
Relaxation Processes ◽  
Dielectric Relaxation Spectroscopy ◽  
Frequency Range ◽  
Polar Groups ◽  
Calculated Activation Energy ◽  
Β Relaxation

ABSTRACTTemperature dependence of measured dielectric relaxation spectra (DRS) in the frequency range 20 Hz - 1 MHz of hydroxyethylcellulose (HEC) are in the temperature range 100 – 350 K. of Arrhenius character with one relaxation process at 150 – 250 K. This process reflects most probably β-relaxation of the side chain groups. Calculated activation energy of this process was 5730 kJ/mole. Four types of polysaccharides were studied at 293 K temperature: hyaluronic acid (HA), chondroitin sulfate (CHS), HEC and carboxymethylcellulose (CMC), in the low-frequency range 10−5 - 100 Hz. Measured dielectric spectra were interpreted as sum of one A.C. conductivity process and of up to two relaxation processes. The relaxation processes were described by means of the Havriliak-Negami formula and their parameters were related to the molecular structure of the polymers. The low value of a in CHS is related to its strong coupling due to the presence of two polar groups in its monomeric unit, whereas low values of α × β are interpreted as being due to the strong steric hindrances caused by long pendants present in HEC.

Effect of ZnO Nano-Particles on The Dielectric Relaxation Behavior and Thermal Stability of Polycarbonate Host

2011 ◽  
Vol 24 (6) ◽  
pp. 837-852 ◽  
Author(s):  
A.A. Al Jaafari ◽  
A.S. Ayesh
Keyword(s):  
Thermal Stability ◽  
Relaxation Time ◽  
Dielectric Relaxation ◽  
Zno Nanoparticles ◽  
Relaxation Behavior ◽  
Nano Particles ◽  
Effect Of Temperature ◽  
Frequency Range ◽  
Dielectric Relaxation Behavior ◽  
Thermal Stability Of

The influence of ZnO nanoparticles on the dielectric properties, dielectric relaxation behavior, and thermal stability of PC host was investigated at different ZnO nanoparticles concentration. The dielectric study was carried out over a frequency range from 500 Hz up to 1 MHz as a function of ZnO concentration. Results obtained from the best fitting of relative permittivity data with Yan and Rhodes model reveal that the dielectric relaxation is not a single relaxation process and there are two values of relaxation time for each nanocomposite at room temperature and domain frequency range. Furthermore, addition of ZnO nanoparticles to PC host changes the dielectric properties of PC, mainly, increases relative permittivity, dielectric loss, and AC conductivity while decreases the impedance values of PC host. Moreover, effect of temperature on AC conductivity of ZnO-PC nanocomposites at 1 kHz was also considered. Besides, dielectric relaxation behavior of PC was investigated at 165°C (above the glass transition temperature of PC) in the domain frequency range. At this elevated temperature (165°C), dielectric loss data shows a single relaxation peak (α-relaxation) in the domain frequency range and was successfully fitted with Debye equation. Also, it was found that as the content of ZnO nanoparticles increases in the PC host the frequency of the peak maximum ( fmax) shifts toward higher frequency value and as a result decreases the value of relaxation time. Additionally, this study shows that the isothermal effect of ZnO nano particles on the α-relaxation of PC host is similar to the effect of temperature. Both of them have a linear dependence with ln( fmax). Furthermore, addition of ZnO nanoparticles to PC host will decrease the thermal stability and glass transition temperature of PC host. Finally, there is a strong evidence from the obtained dielectric and thermal results that addition of ZnO nanoparticles to PC host will highly enhance the chain mobility and also increase the polar character of PC host.

scholarly journals Two distinct dielectric relaxation mechanisms in the low-frequency range in Bi5TiNbWO15 ceramics

2006 ◽  
Vol 88 (16) ◽  
pp. 162908 ◽  
Author(s):  
Z. G. Yi ◽  
Y. X. Li ◽  
Y. Wang ◽  
Q. R. Yin
Keyword(s):  
Dielectric Relaxation ◽  
Low Frequency ◽  
Frequency Range

Ferroelectricity of Chiral Compounds in Highly Ordered Smectic Phases

1989 ◽  
Vol 173 ◽  
Author(s):  
Stanisław Wróbel ◽  
Matthias Pfeiffer ◽  
Ashók M. Biradar ◽  
Wolfgang Haase
Keyword(s):  
Relaxation Time ◽  
Molecular Motion ◽  
Bias Field ◽  
Goldstone Mode ◽  
Electric Permittivity ◽  
Frequency Range ◽  
Chiral Compounds ◽  
Chiral Phases ◽  
Smectic Phases

ABSTRACTMeasurements of the complex electric permitttivity for the Sm C* and for three highly ordered smectic phases: Sm I*, Sm J* and Sm K* of 4- (2 - methylbutyl)-phenyl-4′-(octyloxy)-(1,1′)-biphenyl-4-carboxylate (8 OSI) have been done in the frequency range from 5 Hz to 13 MHz. For the first three chiral phases the Goldstone mode was found with temperature independent critical frequencies, νc = 1.5kHz and the relaxation time τG = 106 μs - for the Sm C* phase, and νc = 1 kHz and τG - 160 μs - for the Sm I* one. In two highly ordered smectics, i.e. Sm J* and Sm K* with inter-layer correlations, the Goldstone mode seems to be suppressed. By applying a D.C. bias field of 1.4 kV/cm the Goldstone mode has been suppressed and shifted towards higher frequencies in both the Sm C* and Sm I* phase. For the Sm J* phase the Goldstone mode is very weak and practically insensitive to the bias field used. In the Sm K* phase there is no Goldstone mode like relaxation, and the only contribution to electric permittivity comes from the fast molecular motion connected with reorientation of molecules about their long axis.

Dynamics of Benzonitrile, Propylene Carbonate and Butylene Carbonate: the Influence of Molecular Shape and Flexibility on the Dielectric Relaxation Behaviour of Dipolar Aprotic Liquids

2000 ◽  
Vol 214 (9) ◽  
Author(s):  
J. Barthel ◽  
R. Buchner ◽  
Ch.G. Hölzl ◽  
M. Münsterer
Keyword(s):  
Relaxation Time ◽  
Dielectric Relaxation ◽  
Propylene Carbonate ◽  
Molecular Shape ◽  
Relaxation Processes ◽  
Relaxation Behaviour ◽  
Frequency Range ◽  
Relaxation Experiments

The results of dielectric relaxation experiments on benzonitrile, propylene carbonate and butylene carbonate, performed between 228.15 K and 338.15 K in the frequency range 0.1 ≤ ν /GHz ≤ 89 are presented. The spectra of the three liquids can be formally fitted with two relaxation processes. The long relaxation time, τ

Low Frequency Dielectric Relaxation and Charge Transport in Bi12TiO20 Photorefractive Sillenite Crystals

2017 ◽  
Vol 753 ◽  
pp. 163-167
Author(s):  
Rene Alejandro Castro ◽  
Nadezhda Ivanovna Anisimova ◽  
Liliya Ansafovna Nabiullina ◽  
Evgeny Borisovich Shadrin
Keyword(s):  
Charge Transport ◽  
Dielectric Relaxation ◽  
Transport Mechanism ◽  
Low Frequency ◽  
Frequency Range ◽  
Thermally Activated ◽  
Relaxation Polarization ◽  
Polarization Mechanism ◽  
Frequency Relaxation ◽  
Thermally Activated Process

Features of processes of a dielectric relaxation and charge transport in photorefractive sillenite crystals Bi12TiO20 at low frequency range are investigated. It was found that the dispersion of dielectric permittivity ε' in crystals Bi12TiO20 is characterized by its growth with lowering frequency and rising temperature. This behaviour may be related to existence of dipole-relaxation polarization mechanism. The frequency dependence of dielectric loss tgδ reveals the existence of low frequency relaxation peaks in the studied temperature range. From the conductivity dependence on the frequency and temperature it was found that conductivity σ increases as frequency increases in the low frequency range. The observed dependence σ(ω)≈Аωs indicates that transport mechanism is due to hopping of carriers via localized electron states. The charge transport is thermally activated process in which activation energy Ea = (0.82±0.03) eV.

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