Electric and dielectric properties of CdSO4-doped borate glasses

2019 ◽  
Vol 33 (04) ◽  
pp. 1950011 ◽  
Author(s):  
E. M. Ahmed
Keyword(s):  
Ac Conductivity ◽  
Thermal Activation ◽  
Relaxation Times ◽  
Wide Distribution ◽  
Ion Density ◽  
Cbh Model ◽  
Oxygen Ion ◽  
Dielectric Data ◽  
Quenching Method ◽  
Loss Formula

A system of (100-x)B2O3⋅xCdSO4glasses (0 [Formula: see text]x [Formula: see text] 40) is set by the ordinary quenching method. Density ([Formula: see text]), molar volume (V[Formula: see text]) and oxygen ion density (N[Formula: see text]) are found to increase with the increase of CdSO4in the samples. The dc conductivity ([Formula: see text]) and the ac conductivity ([Formula: see text]) are measured in the temperature range from 308 to 735 K. [Formula: see text] is found to follow the thermal activation Arrhenius relation with activation energies between 0.36 and 0.76 eV. Ac conductivity and the exponent factor (s) confirm that the CBH model is the origin of the conduction. The dielectric constant ([Formula: see text]) and loss ([Formula: see text]) are studied as a function of the temperature and frequency. The dielectric data are fitted according to the Cole–Cole equations. The values of [Formula: see text] parameter are found to vary between 0.2 and 0.58 which means that these glasses exhibit a wide distribution of relaxation times.

Relaxation processes of some simple aliphatic molecules in dilute solutions

1977 ◽  
Vol 55 (4) ◽  
pp. 297-301 ◽  
Author(s):  
M. P. Madan
Keyword(s):  
Carbon Tetrachloride ◽  
Dielectric Relaxation ◽  
Thermodynamic Parameters ◽  
Relaxation Times ◽  
Relaxation Processes ◽  
Dilute Solutions ◽  
Microwave Region ◽  
Nonpolar Solvents ◽  
Dielectric Data ◽  
Intramolecular Rotation

The dielectric relaxation processes of acetone, cyclohexanone, 4-methyl-2-pentanone, and 4-heptanone in dilute nonpolar solvents, n-heptane, cyclohexane, benzene, and carbon tetrachloride have been studied in the microwave region over a temperature range 10 to 60 °C. The relaxation times and the thermodynamic parameters for the activated states have been determined using the measured dielectric data. The results have been discussed in terms of dipole reorientation by molecular and intramolecular rotation and compared, wherever possible, with other similar studies on aliphatic molecules.

Thermodynamic properties and application of CBH model in the ac conductivity of LiNi1.5P2O7 ceramic

Ionics ◽  
2014 ◽  
Vol 20 (8) ◽  
pp. 1071-1078 ◽  
Author(s):  
R. Ben Said ◽  
B. Louati ◽  
K. Guidara ◽  
S. Kamoun
Keyword(s):  
Thermodynamic Properties ◽  
Ac Conductivity ◽  
Cbh Model

Relaxation processes of quinoline, isoquinoline, and their mixtures

1980 ◽  
Vol 58 (1) ◽  
pp. 20-24 ◽  
Author(s):  
M. P. Madan
Keyword(s):  
Thermodynamic Parameters ◽  
Molecular Motion ◽  
Polar Solvent ◽  
Relaxation Times ◽  
Relaxation Processes ◽  
Polar Components ◽  
Dielectric Absorption ◽  
System A ◽  
Dielectric Data ◽  
Activated State

The dielectric absorption of quinoline, isoquinoline, and their binary mixtures has been studied in the microwave region over a range of temperatures in dilute benzene and n-heptane solutions. The relaxation times and the thermodynamic parameters for the activated state have been determined using the measured dielectric data. The results obtained have been discussed in terms of the molecular motion of the system. A relation has been proposed to represent the relaxation behavior of a system of two Debye-type polar components in a non-polar solvent. The relation has been tested by comparing the calculated values with those determined experimentally for a few systems consisting of similar, simple rigid polar molecules.

AC CONDUCTION PHENOMENON OF Li2O–WO3–B2O3 GLASSES DOPED WITH V2O5

2013 ◽  
Vol 06 (03) ◽  
pp. 1350032 ◽  
Author(s):  
LINGANABOINA SRINIVASA RAO ◽  
NALLURI VEERAIAH ◽  
TUMU VENKATAPPA RAO
Keyword(s):  
High Temperatures ◽  
Ac Conductivity ◽  
Conduction Mechanism ◽  
Glass Composition ◽  
Melt Quenching ◽  
Frequency Exponent ◽  
Spreading Factor ◽  
Cbh Model ◽  
Tan Δ ◽  
Ac Conduction

The glass composition 40 Li 2 O –5 WO 3–(55−x) B 2 O 3: x V 2 O 5 for x = 0.2, 0.4, 0.6 and 0.8 is chosen for the present study. The glass samples were synthesized by conventional melt-quenching technique. The dielectric properties such as constant (ε′), loss (tan δ) and ac conductivity (σac) are carried out as a function of temperature (30–270°C) and frequency (102–105 Hz). The glass sample (at x = 0.6) exhibited highest ac conductivity (σac) and spreading factor (β) among all the samples. All glasses exhibited mixed conduction (both electronic and ionic) at high temperatures. The frequency exponent s denotes the ac conduction mechanism is associated with both QMT model (at low temperatures) and CBH model (at high temperatures).

scholarly journals Master curve generation and modeling of ac conductivity for Mn0.7+xZn0.3SixFe2–2xO4 spinel ferrite system

2017 ◽  
Vol 07 (03) ◽  
pp. 1750022 ◽  
Author(s):  
N. H. Vasoya ◽  
Prafulla K. Jha ◽  
K. G. Saija ◽  
J. A. Bhalodia ◽  
K. B. Modi
Keyword(s):  
Grain Boundaries ◽  
Ac Conductivity ◽  
Spinel Ferrite ◽  
Low Frequency ◽  
Compositional Dependence ◽  
Dielectric Data ◽  
Frequency Regime ◽  
Scaling Process ◽  
And Diffusion ◽  
Ferrite System

The compositional dependence of ac conductivity ([Formula: see text]), real ([Formula: see text]′) and imaginary ([Formula: see text]′′) parts of complex electric conductivity ([Formula: see text]*) was investigated as a function of temperature ([Formula: see text]) and frequency ([Formula: see text] for Mn[Formula: see text]Zn[Formula: see text]SixFe[Formula: see text]O4, [Formula: see text], 0.1, 0.2 and 0.3 spinel ferrite system. The compositional dependence of lattice constant values suggested that the most of the substituted Si[Formula: see text]-ions reside at grain boundaries and only a few Si-ions are inside grains. The variation of [Formula: see text], [Formula: see text], [Formula: see text] is explained on the basis of segregation and diffusion of Si[Formula: see text] ions at grain boundaries and grains, respectively, and the electrode effect. Thermal variation of ac conductivity at fixed frequency suggested two different mechanisms which could be responsible for conduction in the system. It is found that [Formula: see text]* is not the preferred presentation for dielectric data and the scaling process of real part of conductivity by normalized frequency and the scaled frequency were found unsuccessful. The fitting results of ac conductivity data with path percolation approximation were found suitable in low-frequency regime while in high-frequency regime, effective medium approximation (EMA) was found successful.

Dielectric relaxation of dihalobenzenes. I. Ortho and meta Cl2, Br2, and I2 in benzene solution

1968 ◽  
Vol 46 (24) ◽  
pp. 2745-2748 ◽  
Author(s):  
Abhai Mansingh ◽  
David B. McLay
Keyword(s):  
Benzene Solution ◽  
Relaxation Times ◽  
Dielectric Constants ◽  
Cole Plot ◽  
Molecular Reorientation ◽  
Dielectric Data ◽  
Distribution Parameters ◽  
Order Of Magnitude ◽  
The Right ◽  
Right Order

Dielectric data have been measured for the dilute solutions in benzene at 20.0 °C of the ortho- and meta-isomers of dichlorobenzene, dibromobenzene, and diiodobenzene. The "static" dielectric constants have been measured at 100 kHz, the dielectric constants and losses have been measured at both 9.06 and 21.00 GHz, and the refractive indices have been measured at optical wavelengths. Cole–Cole plots can be fitted to the data to yield mean relaxation times τ0 and distribution parameters α. The values of the relaxation times in the ortho-isomers are 11.8, 14.9, and 20.6 ps for dichlorobenzene, dibromobenzene, and diiodobenzene respectively. The corresponding values for the meta-isomers are 8.6, 10.7, and 13.5 ps respectively, values which increase in the same direction with halogen substituent but which are significantly smaller than the relaxation times for the other isomers. All of these times are of the right order of magnitude for molecular reorientation and there is no evidence for dipole–dipole interactions. Although the nonzero values of the distribution parameters will allow mathematical descriptions in terms of two relaxation times τ1 and τ2, the values derived from two such descriptions yield two unrealistic relaxation times for each molecule. It is concluded that the analysis based on the Cole–Cole plot gives the most meaningful results.

Microwave Absorption and Relaxation Behavior of Some Simple Ketones in Dilute Solutions

1975 ◽  
Vol 53 (1) ◽  
pp. 23-28 ◽  
Author(s):  
M. P. Madan
Keyword(s):  
Relaxation Time ◽  
Thermodynamic Parameters ◽  
Microwave Absorption ◽  
Reasonable Agreement ◽  
Relaxation Times ◽  
Relaxation Behavior ◽  
The Other ◽  
Dielectric Absorption ◽  
Dielectric Data ◽  
Thermodynamic Processes

The dielectric absorption of solutions of 2-hexanone, 4- and 5-nonanone, and 2-decanone has been examined in the microwave region over a range of temperatures in n-heptane, cyclohexane, and benzene. The relaxation times and the thermodynamic parameters for the activated states have been determined using the measured dielectric data. The values of relaxation time are in reasonable agreement at the temperature at which there are available known data. Both the relaxation behavior and the thermodynamic processes are discussed and, where possible, compared with corresponding results of the other workers.

scholarly journals Estimation of The Electrical and Dielectric Properties For Se98Te2 and Se96Te2X2 (X = Zn and Cd) Amorphous Films.

2021 ◽  
Author(s):  
Amira Shakra ◽  
M. Fadel ◽  
A.E. Kalila
Keyword(s):  
Thin Films ◽  
Dielectric Properties ◽  
Conduction Mechanism ◽  
Charge Carriers ◽  
Amorphous Films ◽  
Thermal Evaporation Method ◽  
Cbh Model ◽  
X Ray ◽  
Electrical And Dielectric Properties ◽  
Quenching Method

Abstract Bulk glassy Se98Te2 and Se96Te2X2 (X = Zn and Cd) were prepared by melting quenching method. Thin films of various thicknesses (200 – 670 nm) were obtained by the thermal evaporation method. The structure of the prepared compositions was investigated by X-ray and EDX analysis. We studied the effect of Zn and Cd addition on the electric and dielectric properties of Se98Te2 thin films. Our measurements were studied in the temperature range (298-323K) below the glass transition temperature and frequency range (100 Hz-1 MHz). DC conductivity showed a single conduction mechanism by hopping of charge carriers at the band edges for the studied system. The dependence of Ac conductivity on frequency is linear with frequency exponent s lies very close to unit and is independent of temperature. This can be explained by the correlated barrier hopping (CBH) model. The dielectric constant ε1 and dielectric loss ε2 noticed to decrease with frequency and increase with temperature. The maximum barrier height Wm was calculated according to Guinitin.

scholarly journals The structure of high altitude O<sup>+</sup> energization and outflow: a case study

2004 ◽  
Vol 22 (7) ◽  
pp. 2497-2506 ◽  
Author(s):  
H. Nilsson ◽  
S. Joko ◽  
R. Lundin ◽  
H. Rème ◽  
J.-A. Sauvaud ◽  
...  
Keyword(s):  
High Altitude ◽  
Flow Direction ◽  
Correlation Coefficients ◽  
Dispersion Analysis ◽  
Observation Point ◽  
Ion Density ◽  
Oxygen Ion ◽  
Ion Energization ◽  
Upstream Flow

Abstract. Multi-spacecraft observations from the CIS ion spectrometers on board the Cluster spacecraft have been used to study the structure of high-altitude oxygen ion energization and outflow. A case study taken from 12 April 2004 is discussed in more detail. In this case the spacecraft crossed the polar cap, mantle and high-altitude cusp region at altitudes between 4RE and 8RE and 2 of the spacecraft provided data. The oxygen ions were seen as a beam with narrow energy distribution, and increasing field-aligned velocity and temperature at higher altitude further in the upstream flow direction. The peak O+ energy was typically just above the highest energy of observed protons. The observed energies reached the upper limit of the CIS ion spectrometer, i.e. 38keV. Moment data from the spacecraft have been cross-correlated to determine cross-correlation coefficients, as well as the phase delay between the spacecraft. Structures in ion density, temperature and field-aligned flow appear to drift with the observed field-perpendicular drift. This, together with a velocity dispersion analysis, indicates that much of the structure can be explained by transverse heating well below the spacecraft. However, temperature isotropy and the particle flux as a function of field-aligned velocity are inconsistent with a single altitude Maxwellian source. Heating over extended altitude intervals, possibly all the way up to the observation point, seem consistent with the observations.

AC conductivity and dielectric relaxation of Se80−xTe20Bix (x=6, 12) glasses

2019 ◽  
Vol 60 (6) ◽  
pp. 222-230
Author(s):  
Deepika Deepika ◽  
Hukum Singh
Keyword(s):  
Dielectric Relaxation ◽  
Ac Conductivity ◽  
Lower Energy ◽  
Dielectric Relaxation Time ◽  
Frequency Exponent ◽  
Dielectric Parameters ◽  
Cbh Model ◽  
Increase With Increase ◽  
Different Temperatures ◽  
Frequency Temperature

The present paper reports the ac conductivity and dielectric relaxation of Se80−xTe20Bix (x=6, 12) glasses at various temperatures and frequencies. It was found that ac conductivity increases on increase of frequency, temperature as well as Bi content. The increase in conductivity is due to the formation of lower energy Se–Bi and Te–Bi bonds which takes the system to a stable lower energy configuration. The values of frequency exponent (s) were calculated and it was found that samples obey CBH model of conduction. Density of states (N(Ef)) near the fermi level were calculated at different temperatures and it was found that addition of Bi increases the number of localised states in the tails which leads to increase in ac conductivity. Further, it was found that dielectric parameters increase with increase in temperature. However, a decrease in both dielectric constant (ε′) and dielectric loss ((ε″) was observed with increase in frequency. Beside this, dielectric relaxation time (τ) and activation energy of relaxation (∆Eτ) were also determined for both the samples under study and was found to be lower for Se68Te20Bi12 glass.

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