Transient Response of the System Al/Al2O3/Electrolyte. Part I. Galvanostatic Transients

1972 ◽  
Vol 50 (20) ◽  
pp. 3259-3266 ◽  
Author(s):  
D. G. W. Goad ◽  
M. J. Dignam
Keyword(s):  
Dielectric Relaxation ◽  
Transient Response ◽  
Ion Current ◽  
Relaxation Processes ◽  
Relaxation Model ◽  
Exact Agreement ◽  
Voltage Transients ◽  
Galvanostatic Conditions ◽  
Transient Measurements

Voltage transients under galvanostatic conditions are investigated for the system Al/Al2O3/electrolyte (glycol–borate) and the results, along with similar results obtained by Dewald for the system Ta/Ta2O5/electrolyte (0.1 N H2SO4), are analyzed according to the dielectric relaxation model due to Dignam. This model accounts for the general form of the transients, but systematic discrepancies are apparent. Modification of the model to include two independent ion-current-driven dielectric relaxation processes gives essentially exact agreement with the data and values for the constants in accord with those obtained earlier from potentiostatic transient measurements.

scholarly journals Transient Response of the System Al/Al2O3/Electrolyte. Part II. A.c. Impedance Measurements During Steady-State Film Growth

1972 ◽  
Vol 50 (20) ◽  
pp. 3267-3271 ◽  
Author(s):  
D. G. W. Goad ◽  
M. J. Dignam
Keyword(s):  
Steady State ◽  
Film Growth ◽  
Angular Frequency ◽  
Ion Current ◽  
Effective Dielectric Constant ◽  
Relaxation Processes ◽  
Relaxation Model ◽  
Impedance Measurements ◽  
Capacitive Element ◽  
Experimental Scatter

Experiments are described in which the a.c. impedance of the system Al/Al2O3/electrolyte (glycol–borate) is measured under conditions of steady-state film growth. Using an equivalent circuit of a resistive and capacitive element in parallel, the results are presented in the form of the a.c. conductance, σac, and effective dielectric constant, Keff, of the oxide film as a function of the d.c. current density, I0, and angular frequency ω. The results show that σac/I0 and Keff vary with (ω/I0), but within experimental error are independent of ω and I0 separately. The dielectric relaxation model, assuming two ion-current-driven relaxation processes and using the constants determined in Part I, reproduces the data almost within experimental scatter. A poorer fit is achieved if only one relaxation process is assumed.

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.

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.

On the temperature and pressure dependence of dielectric relaxation processes in ionic liquids

2021 ◽  
Author(s):  
Florian Pabst ◽  
Zaneta Wojnarowska ◽  
Marian Paluch ◽  
Thomas Blochowicz
Keyword(s):  
Ionic Liquids ◽  
Dielectric Relaxation ◽  
Pressure Dependence ◽  
Dynamic Processes ◽  
Relaxation Processes ◽  
Dielectric Spectra ◽  
Temperature And Pressure ◽  
Microscopic Origin

The temperature and pressure dependence of two dynamic processes in the dielectric spectra of five supercooled ionic liquids equipped with octyl-chains are reported. The microscopic origin of these processes is discussed.

AC Loss Modeling in Ba0.5Sr0.5TiO3 Using Dielectric Relaxation

2004 ◽  
Vol 833 ◽  
Author(s):  
Nadia K. Pervez ◽  
Jiwei Lu ◽  
Susanne Stemmer ◽  
Robert A. York
Keyword(s):  
Dielectric Loss ◽  
Dielectric Relaxation ◽  
Power Law ◽  
Fractional Power ◽  
Ac Loss ◽  
Dielectric Susceptibility ◽  
Network Analyzer ◽  
Q Factor ◽  
Relaxation Model ◽  
Q Factors

ABSTRACTIn universal relaxation, a material's complex dielectric susceptibility follows a fractional power law f1-n where 0 < n < 1 over multiple decades of frequency. In a variety of materials, including Ba0.5Sr0.5Ti03, dielectric relaxation has been observed to follow this universal relaxation model with values of n close to 1. In this work we have shown that the universal relaxation model can be used to calculate dielectric loss even when n is very close to 1. Our calculated Q-factors agree with measured values at 1 MHz; this agreement suggests that this technique may be used for higher frequencies where network analyzer measurements and electrode parasitics complicate Q-factor determination.

Modeling of Dielectric Relaxation Processes in Moist Sand Rocks

2017 ◽  
Vol 60 (4) ◽  
pp. 711-716 ◽  
Author(s):  
P. P. Bobrov ◽  
V. N. Krasnoukhova ◽  
E. S. Kroshka ◽  
A. S. Lapina
Keyword(s):  
Dielectric Relaxation ◽  
Relaxation Processes ◽  
Moist Sand
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