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.

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 Amorphous Diamond-Like Carbon Film Growth by KrF-and Arf-Excimer Laser Pld: Correlation with Plume Properties

1995 ◽  
Vol 388 ◽  
Author(s):  
A. A. Puretzky ◽  
D. B. Geohegan ◽  
G. E. Jellison ◽  
M. M. Mcgibbon
Keyword(s):  
Film Growth ◽  
Carbon Film ◽  
Laser Deposition ◽  
Ion Current ◽  
Diamond Like Carbon ◽  
Krf Laser ◽  
Arf Excimer Laser ◽  
Arf Laser ◽  
Carbon Plasma ◽  
Deposited Films

AbstractA comparative study of arF- and KrF-laser deposition of amorphous diamond-like carbon (DLC) films and relevant carbon plasmas has been performed. Spectroscopic ellipsometry and EELS analysis of the DLC films deposited on Si <100> and NaCl substrates were utilized to characterize the high quality arF- and KrF-laser deposited films (up to 84% of sp3 bonded carbon in 7 J/cm2 -ArF-laser DLC film). Gated ICCD imaging, luminescence and ion current probe diagnostics of the carbon plume have revealed quite different properties of carbon plasmas generated by arF- and KrF- lasers. KrF-laser (6.7 J/cm2) irradiation produces a less energetic carbon plasma containing larger amounts of C2 and probably larger clusters compared with arF-laser irradiation at the same energy fluence. We conclude that the more energetic and highly-atomized arF-laser carbon plasma results in the better diamond-like properties.

Study Of Cobalt Doped Gdalo3 For Electrochemical Application

2020 ◽  
Vol 16 ◽  
Author(s):  
Jisha P. Kunhan ◽  
Prashantha S. Chandrappa ◽  
C.R Ravikumar ◽  
Nagabhushana Hanumantharayappa ◽  
Ramachandra Naik ◽  
...  
Keyword(s):  
Steady State ◽  
Electrochemical Impedance ◽  
Combustion Method ◽  
Cobalt Nitrate ◽  
Future Perspective ◽  
Frequency Range ◽  
Solution Combustion ◽  
Impedance Measurements ◽  
Gadolinium Nitrate ◽  
Ftir Spectral Analysis

BACKGROUND: Nano perovskite-type structure as denoted by ABO3 (A= RE) have been popular targets of fundamental investigations since they exhibit a wide variety of physical properties depending upon the chemical composition, defects and small changes in atomic arrangements. METHODS: GdAlO3:Co2+ (1, 3 &9 mol %) synthesized using the solution combustion method by using stoichiometric quantities of gadolinium nitrate [Gd (NO3)3], aluminium nitrate (Al (NO3)2, cobalt nitrate Co(NO3)2. RESULTS: The morphology, structure and particle size of the prepared GdAlO3:Co2+ sample characterized by transmission electron microscope (TEM) image. The Fourier transform infrared (FTIR) spectral analysis confirms that the as-prepared powder itself is in pure phase. Electrochemical impedance measurements (EIS) of different GdAlO3: Co2+ samples were measured vs Ag/AgCl in the frequency range of 1 Hz to 1 MHz with AC amplitude of 5 mV at steady-state which clearly indicates that Co2+ dopant was successful doping material for the fabrication of supercapacitors. CONCLUSION: Electrochemical impedance measurements (EIS) of different GdAlO3: Co2+ samples were measured vs Ag/AgCl in the frequency range of 1 Hz to 1 MHz with AC amplitude of 5 mV at steady-state which clearly indicates that Co2+ dopant was successful doping material for the fabrication of supercapacitors. As a future perspective, we believe that GdAlO3:Co2+ composite material could be a promising electrode material for the fabrication of various sensors, supercapacitors and solar cells.

scholarly journals Effect of Operating Temperature on Individual Half-Cell Reactions in All-Vanadium Redox Flow Batteries

Batteries ◽  
2018 ◽  
Vol 4 (4) ◽  
pp. 55 ◽  
Author(s):  
Ruediger Schweiss ◽  
Christian Meiser ◽  
Dana Dan
Keyword(s):  
Steady State ◽  
Operating Temperature ◽  
Cell Reaction ◽  
Half Cell ◽  
Impedance Measurements ◽  
Flow Cells ◽  
Current Densities ◽  
Redox Flow Cells ◽  
The Individual ◽  
Vanadium Redox

Systematic steady-state measurements were performed in order to investigate the effect of operating temperature on the individual half-cell reactions in all vanadium redox flow cells. Results confirm that the kinetic losses are dominated by the negative half-cell reaction. Steady-state polarization and AC impedance measurements allowed for extraction of kinetic parameters (exchange current densities, activation energy) of the corresponding half-cell reaction.

scholarly journals Dynamics of Excitation and Inhibition in the Light-Adapted Limulus Eye in situ

1971 ◽  
Vol 58 (1) ◽  
pp. 1-19 ◽  
Author(s):  
Marguerite Biederman-Thorson ◽  
John Thorson
Keyword(s):  
Steady State ◽  
Lateral Inhibition ◽  
Low Frequency ◽  
Dynamic Responses ◽  
Relaxation Processes ◽  
Pass Filter ◽  
Generator Potential ◽  
Low Pass Filter ◽  
Low Pass

The dynamics of spike discharge in eccentric cell axons from the in situ lateral eye of Limulus, under small sinusoidal modulation of light to which the eye is adapted, are described over two decades of light intensity and nearly three decades of frequency. Steady-state lateral inhibition coefficients, derived from the very low-frequency response, average 0.04 at three interommatidial spacings. The gain vs. frequency of a singly illuminated ommatidium is described closely from 0.004 to 0.4 cps by the linear transfer function s0.25; this function also accounts approximately for the measured phase leads, the small signal adaptation following small step inputs, and for Pinter's (1966) earlier low-frequency generator potential data. We suggest that such dynamics could arise from a summation in the generator potential of distributed intensity-dependent relaxation processes along the dendrite and rhabdome. Analysis of the dynamic responses of an eccentric cell with and without simultaneously modulated illumination of particular neighbors indicates an effect equivalent to self-inhibition acting via a first-order low-pass filter with time constant 0.42 sec, and steady-state gain near 4.0. The corresponding filters for lateral inhibition required time constants from 0.35 to 1 sec and effective finite delay of 50–90 msec.

A model for surface charge-assisted barrier film growth on metals in acidic solutions based on ac impedance measurements

1996 ◽  
Vol 41 (17) ◽  
pp. 2695-2705 ◽  
Author(s):  
M. Bojinov ◽  
I. Kanazirski ◽  
A. Girginov
Keyword(s):  
Surface Charge ◽  
Film Growth ◽  
Ac Impedance ◽  
Impedance Measurements ◽  
Acidic Solutions ◽  
Barrier Film

Harmonic Vibrations in Thermoelasticity of Microstretch Materials

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Marin Marin
Keyword(s):  
Steady State ◽  
Lateral Surface ◽  
Boundary Data ◽  
Heat Supply ◽  
Critical Frequency ◽  
Body Force ◽  
Decay Estimate ◽  
Angular Frequency ◽  
Plane Boundary ◽  
Harmonic Vibrations

Consider a cylinder made of a microstretch thermoelastic material for which one plane end is subjected to plane boundary data varying harmonically in time. On the lateral surface and other base, we have zero body force and heat supply. By using a Toupin type measure associated with the corresponding steady-state vibration, and by assuming that the angular frequency of oscillations is lower than a certain critical frequency, we show that the amplitude of the vibrations decays exponentially with the distance to the base. This decay estimate is similar to that of the Saint-Venant type.

scholarly journals Relaxation model of dynamic deformation of elastic-plastic media

2020 ◽  
pp. 36-43
Author(s):  
P.V. Makarov ◽  
Keyword(s):  
Strain Rate ◽  
External Action ◽  
Model Parameters ◽  
Relaxation Processes ◽  
Relaxation Model ◽  
Plastic Medium ◽  
Elastic Plastic ◽  
Relaxation Of Stresses ◽  
Local Relaxation ◽  
Induced Defects

A variant is considered for the relaxation model of a loaded elastic-plastic medium with dislocation kinetics of plastic shearing. The model is formulated in rates and includes two independent strain rates: total strain rate, which corresponds to the rate of external action, and local rate of plastic response of the material, which represents the ability of the medium to generate strain-induced defects. This makes it possible to describe both local relaxation processes in the elastic-plastic medium and average relaxation of stresses in a loaded specimen. The model being developed amounts to microscopic ones. All model parameters are determined from independent experiments for the evolution of the dislocation continuum during loading of macroscopic specimens. The model provides an adequate description of the dynamic effects of the macroscopic response of materials depending on the strain rate: the upper and lower yield points (yield drop, yield plateau), subsequent strain hardening as well as features of cyclic and alternating loading, ideal and nonideal Bauschinger effect.

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