Hydrogen Diffusion Mechanism in Amorphous Silicon From D Tracer Diffusion: Theory and Experiment

1993 ◽  
Vol 297 ◽  
Author(s):  
Howard M. Branz ◽  
Sally Asher ◽  
Brent P. Nelson ◽  
Mathieu Kemp
Keyword(s):  
Hydrogen Diffusion ◽  
Diffusion Mechanism ◽  
Effective Diffusion ◽  
Early Time ◽  
Deep Trap ◽  
Tracer Diffusion ◽  
Release Time ◽  
Decay Length ◽  
Trap Level ◽  
The Mean

We compare experimental diffusion studies to the results of a theoretical study of diffusion controlled by a single deep trap level. Analytic solutions for the D profiles after annealing depend on the characteristic H release time, τ, from the deep trap. At times much shorter than τ, the D profile develops exponential wings whose decay length is the mean D displacement between trapping events. The long-time D profile is a solution to the ideal diffusion equation, but with an effective diffusion coefficient that can be calculated from features of the early-time profiles. New experimental data establish the validity of the model at a range of anneal times and temperatures. We also find that the mean displacement of free H before retrapping decreases with both increased illumination and increasing anneal temperature.

An embedded-atom method interatomic potential for Pd–H alloys

2008 ◽  
Vol 23 (3) ◽  
pp. 704-718 ◽  
Author(s):  
X.W. Zhou ◽  
J.A. Zimmerman ◽  
B.M. Wong ◽  
J.J. Hoyt
Keyword(s):  
Computational Models ◽  
Mechanical Response ◽  
Hydrogen Diffusion ◽  
Interatomic Potential ◽  
Diffusion Mechanism ◽  
Miscibility Gap ◽  
Embedded Atom Method ◽  
Embedded Atom ◽  
Formidable Challenge ◽  
Embedded Atom Method Potential

Palladium hydrides have important applications. However, the complex Pd–H alloy system presents a formidable challenge to developing accurate computational models. In particular, the separation of a Pd–H system to dilute (α) and concentrated (β) phases is a central phenomenon, but the capability of interatomic potentials to display this phase miscibility gap has been lacking. We have extended an existing palladium embedded-atom method potential to construct a new Pd–H embedded-atom method potential by normalizing the elemental embedding energy and electron density functions. The developed Pd–H potential reasonably well predicts the lattice constants, cohesive energies, and elastic constants for palladium, hydrogen, and PdHx phases with a variety of compositions. It ensures the correct hydrogen interstitial sites within the hydrides and predicts the phase miscibility gap. Preliminary molecular dynamics simulations using this potential show the correct phase stability, hydrogen diffusion mechanism, and mechanical response of the Pd–H system.

Diffusion of Zinc in Two-Phase Mg-Al Alloy

2007 ◽  
Vol 263 ◽  
pp. 189-194
Author(s):  
Ivo Stloukal ◽  
Jiří Čermák
Keyword(s):  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Effective Diffusion ◽  
Residual Activity ◽  
Diffusion Path ◽  
Al Alloy ◽  
Serial Sectioning ◽  
Two Phase ◽  
Interphase Boundaries ◽  
The Mean

Coefficient of 65Zn heterodiffusion in Mg17Al12 intermetallic and in eutectic alloy Mg - 33.4 wt. % Al was measured in the temperature region 598 – 698 K using serial sectioning and residual activity methods. Diffusion coefficient of 65Zn in the intermetallic can be written as DI = 1.7 × 10-2 m2 s-1 exp (-155.0 kJ mol-1 / RT). At temperatures T ≥ 648 K, where the mean diffusion path was greater than the mean interlamellar distance in the eutectic, the effective diffusion coefficient Def = 2.7 × 10-2 m2 s-1 exp (-155.1 kJ mol-1 / RT) was evaluated. At two lower temperatures, the diffusion coefficients 65Zn in interphase boundaries were estimated: Db (623 K) = 1.6 × 10-12 m2 s-1 and Db (598 K) = 4.4 × 10-13 m2 s-1.

scholarly journals Diffusion Mechanism of Leading Technology in the New Energy Industry Based on the Bass Model

2021 ◽  
Vol 9 ◽  
Author(s):  
Hongying Wang ◽  
Bing Sun
Keyword(s):  
Expected Utility ◽  
Simulation Analysis ◽  
Diffusion Mechanism ◽  
Effective Diffusion ◽  
Energy Industry ◽  
Bass Model ◽  
Property Development ◽  
Industrial Transformation ◽  
New Energy ◽  
The Government

With the increasing difficulties associated with heating, the new energy industry has become the mainstay for property development. The effective diffusion of leading technologies supplies a social edge for enterprise core technologies, and this is also a necessary topic for industrial transformation and optimization. Within the international context of energy conservation and emission reduction, the scientific and in-depth study of the diffusion mechanisms underlying leading technologies in the new energy industry have vital theoretical significance for the promotion of the diffusion of leading technologies. Based on the introduction of the Bass model and one extension model, this paper constructs the diffusion model of the new energy industry’s leading technology and analyzes its diffusion mechanism. The identified mechanism indicates that in the case of imperfect market and policy environments, the diffusion of the leading technology of the new energy industry is mainly influenced by the “expected utility” of innovators and the “actual utility” of imitators. The diffusion of the leading technology in innovator enterprises of the new energy industry is mainly affected by the “expected utility,” while the diffusion in imitator enterprises is affected by the “actual utility.” These influences are verified by simulation analysis. Based on the diffusion mechanism, several suggestions are presented for the promotion of the diffusion mechanism of leading technology, with the aim to provide references for the government, industry associations, and enterprises for relevant decision-making.

Beyond the Cahn-Hilliard Equation: a Vacancy-Based Kinetic Theory

2011 ◽  
Vol 172-174 ◽  
pp. 321-330 ◽  
Author(s):  
Maylise Nastar
Keyword(s):  
Kinetic Theory ◽  
Structure Function ◽  
Diffusion Mechanism ◽  
Kinetic Equations ◽  
Mean Field ◽  
Early Time ◽  
Present Theory ◽  
Kinetic Coupling ◽  
Amplification Rate ◽  
Cahn Hilliard Equation

A Self-Consistent Mean Field (SCMF) kinetic theory including an explicit description ofthe vacancy diffusion mechanism is developed. The present theory goes beyond the usual local equi-librium hypothesis. It is applied to the study of the early time spinodal decomposition in alloys. Theresulting analytical expression of the structure function highlights the contribution of the vacancydiffusion mechanism. Instead of the single amplification rate of the Cahn-Hillard linear theory, thelinearized SCMF kinetic equations involve three constant rates, first one describing the vacancy re-laxation kinetics, second one related to the kinetic coupling between local concentrations and paircorrelations and the third one representing the spinodal amplification rate. Starting from the same va-cancy diffusion model, we perform kineticMonte Carlo simulations of a Body Centered Cubic (BCC)demixting alloy. The resulting spherically averaged structure function is compared to the SCMF pre-dictions. Both qualitative and quantitative agreements are satisfying.

Capture and emission of electrons at 2.4-eV-deep trap level in SiO2films

1975 ◽  
Vol 11 (12) ◽  
pp. 5023-5030 ◽  
Author(s):  
D. J. DiMaria ◽  
F. J. Feigl ◽  
S. R. Butler
Keyword(s):  
Deep Trap ◽  
Trap Level

Abstract 3173: Imaging Findings at the Earliest Stages of Intracerebral Hemorrhage

Stroke ◽  
2012 ◽  
Vol 43 (suppl_1) ◽  
Author(s):  
Adrian M Burgos ◽  
Nerses Sanossian ◽  
David Liebeskind ◽  
Leonid Groysman ◽  
Pablo Villablanca ◽  
...  
Keyword(s):  
Intracerebral Hemorrhage ◽  
Brain Imaging ◽  
Early Time ◽  
Field Evaluation ◽  
Imaging Findings ◽  
Imaging Studies ◽  
Lentiform Nucleus ◽  
History Of ◽  
The Mean ◽  
Fazekas Scale

Background: Imaging findings in intracerebral hemorrhage (ICH) patients at ultra-early time points have not been well characterized. Objective: To describe imaging findings in consecutive ICH patients being transported by ambulance within 2 hours from symptom onset. Methods: We analyzed consecutive ICH patients enrolled in the multicenter, NIH Field Administration of Stroke Therapy (FAST-MAG) clinical trial. First brain imaging studies obtained in the ED were independently reviewed by 2 neurologists for ICH location, volume, presence of intraventricular hemorrhage (IVH), heterogeneity (defined as >20 point difference in Hounsfield units), irregular borders, multilobulation, and substantial edema (defined as >0.5cm). Leukoaraiosis was graded using the Fazekas scale for periventricular and deep white matter changes (0-3 for each). Results: Among 127 patients (enrolled en route to 23 hospitals), mean age was 66 (SD 14), 34% were women, 35% had Hispanic ethnicity, 83% were white, and 84% had a history of HTN. At time of first field evaluation by paramedics [mean 31 (SD 23) minutes after last known well time (LKWT)], the initial BP was 177/95 (SD 34/22) and median (IQR) Glasgow Coma Scale of 15 (15-15). First brain imaging studies were obtained a mean of 100 (SD 35, range 54-255) minutes after LKWT, and were CT in 90% and MRI in 10%. Location of ICH was most often in the lentiform nucleus (42%) followed by thalamus (40%), and cortex (4%), with one case each of caudate, pons, and cerebellar deep nuclei. The mean volume of initial hematoma was 19.6 (SD 23) ml. IVH was present in 45 (35%), significant edema in 13 (10%), and midline shift in 24 (19%). Hemorrhage density was heterogeneous in 34 (27%), multilobulated in 55 (43%) and with irregular borders in 77 (60%). Leukoaraiosis (LA) was common, with moderate to severe LA (Fazekas grades 2, 3) present in the periventricular region in 58% and deep regions centrum semiovale in 35%. Conclusions: Among ICH patients presenting within the first 2h, deep hemorrhages predominate over superficial and intraventricular extension is already present in one-third, but ICH volume is moderate and substantial edema present in only one-tenth. These findings suggest substantial opportunities for intervention to avert hemorrhage and edema growth ultra-early after ICH onset.

Effect of cold rolling on hydrogen diffusion and trapping in X70 pipeline steel

2020 ◽  
pp. 1-28
Author(s):  
Alen Thomas ◽  
Jerzy Szpunar
Keyword(s):  
Cold Rolling ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
Pipeline Steel ◽  
Effective Diffusion ◽  
Diffusion Path ◽  
X70 Pipeline Steel ◽  
Diffusion Parameters ◽  
Intensity Changes ◽  
Diffusion Intensity

Abstract In this investigation, we prepared samples with five different grain misorientations by cold rolling an X70 pipeline steel plate. The hydrogen permeation and hydrogen visualization experiments were used to compute the diffusion parameters and to reveal the diffusion path in steel samples. The dual-polarized permeation experiment allowed us to show that permeability and effective diffusion coefficient were decreased with an increase in misorientation. Hence, the total and irreversible trapping sites were also raised with the extent of deformation in the steel. On the other hand, the visualization study permitted us to show that hydrogen diffusion intensity changes within the microstructure. The diffusion intensity increases in the order of non-deformed grains, grain boundaries and deformed grains with deformed grains as the easiest path for hydrogen diffusion.

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