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.

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 Spectroscopic analysis and temperature-dependent dielectric properties of bulk Ni–Zn ceramics

2019 ◽  
Vol 09 (02) ◽  
pp. 1950014
Author(s):  
Anand Yadav ◽  
Pankaj Choudhary ◽  
P. Saxena ◽  
V. N. Rai ◽  
A. Mishra
Keyword(s):  
Dielectric Constant ◽  
Ac Conductivity ◽  
Room Temperature ◽  
Lattice Structure ◽  
Dielectric Behavior ◽  
Tangent Loss ◽  
Temperature Dependent ◽  
Dielectric Parameters ◽  
Increase With Increase ◽  
Ion Substitution

In the present work, series of Zn ion-doped Ni[Formula: see text]ZnxFe2O4 ([Formula: see text]) ceramics were prepared by the double sintered solid-state reaction route to find out the influence of Zn[Formula: see text] ions on the crystal structure, lattice structure and dielectric behavior of parent NiFe2O4. X-ray diffraction (XRD) study favors that all the prepared compounds belong to the cubic spinel structure. Lattice parameters found to have increasing value with increased Zn[Formula: see text] ion substitution. The Raman scattering measurement discerns optical-active modes with blue shift as the doping increases. The dielectric constant ([Formula: see text] and dielectric tangent loss (tan [Formula: see text] decrease with an increase in frequency and at higher frequency, both become constant. Dielectric parameters observe nonlinear behavior with increasing Zn[Formula: see text] ion substitution. Room temperature dielectric constant of 10% Zn ion-doped NiFe2O4 [Ni[Formula: see text]Zn[Formula: see text]Fe2O4] is much higher as compared to other prepared ceramics. The room temperature ac conductivity is found to increase with increase in frequency and temperature-dependent ac conductivity increases with increase in temperature.

scholarly journals Dielectric Relaxation of Benzonitrile in Benzene

2008 ◽  
Vol 63 (12) ◽  
pp. 813-818
Author(s):  
Rajesh Kumar ◽  
Nagesh Thakur ◽  
Rajendra S. Bisht
Keyword(s):  
Dielectric Relaxation ◽  
Viscous Flow ◽  
Single Frequency ◽  
Dielectric Relaxation Time ◽  
Relaxation Processes ◽  
Flow Process ◽  
Energy Parameters ◽  
Different Temperatures ◽  
Rate Processes ◽  
Microwave Techniques

The dielectric constant, ε′ , and dielectric loss, ε″ , of dilute solutions of benzonitrile (C6H5CN) in benzene have been measured at 9.885 GHz at 25, 30, 35, and 40 °C using standard standing microwave techniques. Following the single frequency concentration variational method of Gopala Krishna, the dielectric relaxation time, τ , and the dipole moment, μ, at various temperatures have been calculated. It was concluded that dielectric relaxation processes can be treated as rate processes just like the viscous flow process. Based on the above studies, the monomer structure of benzonitrile in benzene has been inferred. The solute-solvent molecular association of benzonitrile in benzene has been found. The energy parameters ΔHε , ΔFε , ΔSε for the dielectric relaxation process of benzonitrile in benzene at different temperatures have been calculated and compared with the corresponding energy parameters ΔHη , ΔFη , ΔSη for the viscous flow process.

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

EFFECT OF CELL THICKNESS ON THE DIELECTRIC RELAXATION PROCESSES IN FERROELECTRIC LIQUID CRYSTALS

2008 ◽  
Vol 22 (14) ◽  
pp. 2263-2273 ◽  
Author(s):  
RAJBIR SINGH ◽  
K. K. RAINA
Keyword(s):  
Liquid Crystal ◽  
Dielectric Relaxation ◽  
Dielectric Strength ◽  
Relaxation Processes ◽  
Goldstone Mode ◽  
Ferroelectric Liquid Crystal ◽  
Dielectric Relaxation Spectroscopy ◽  
Dielectric Parameters ◽  
Liquid Crystal Material ◽  
Cell Thickness

Dielectric relaxation spectroscopy in the frequency range 50 Hz to 1 MHz has been carried out in a room temperature ferroelectric liquid crystal mixture in the SmC*, SmA and N* phases in cells of different thickness. The relaxation frequency fr, distribution parameter α and dielectric strength δ∊ have been evaluated. Goldstone mode, domain mode and soft mode have been observed. It is found that the cell thickness has a significant effect on the dielectric parameters of the ferroelectric liquid crystal material. The results have been discussed.

The “Fractional” Kinetic Equations and General Theory of Dielectric Relaxation

2005 ◽  
Author(s):  
Raoul R. Nigmatullin
Keyword(s):  
General Theory ◽  
Dielectric Relaxation ◽  
Collective Motion ◽  
Kinetic Equations ◽  
Heterogeneous Materials ◽  
Complex Conjugate ◽  
Electric Circuits ◽  
Self Similar ◽  
Fractional Kinetic Equations ◽  
Frequency Temperature

Based on the Mori-Zwanzig formalism it becomes possible to suggest a general decoupling procedure, which reduces a wide set of various micromotions distributed over a self-similar structure to a few collective/reduced motions describing the relaxation/exchange behavior of a complex system in the mesoscale region. The frequency dependence of the reduced collective motion contains real and pair of complex-conjugate power-law exponents in the frequency domain and explains naturally the “universal response” (UR) phenomenon discovered by A. Jonscher in a wide class of heterogeneous materials. This strict mathematical result allows in developing a consistent and general theory of dielectric relaxation that can describe wide set of dielectric spectroscopy (DS) data measured in some frequency/temperature range in many heterogeneous materials. Based on this result it becomes possible also to suggest a new set of two-pole elements, which generalizes the conventional RLC-elements and can constitute the basis of new theory of the linear electric circuits.

Dielectric relaxation time and dipole moment of isometric butanols in benzene solutions.

1983 ◽  
Vol 26 (2) ◽  
pp. 77-84 ◽  
Author(s):  
S.M. Khameshara ◽  
M.S. Kavadia ◽  
M.S. Lodha ◽  
D.C. Mathur ◽  
V.K. Vaidya
Keyword(s):  
Dipole Moment ◽  
Relaxation Time ◽  
Dielectric Relaxation ◽  
Dielectric Relaxation Time
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