Hydrogen Diffusion and Solubility in A-Si:H

1994 ◽  
Vol 336 ◽  
Author(s):  
Wolfhard Beyer ◽  
Heribert Wagner
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Concentration ◽  
Hydrogen Diffusion ◽  
Diffusion Length ◽  
Activation Energies ◽  
Free Energies ◽  
Constant Diffusion ◽  
Substrate Temperatures ◽  
Concentration Diffusion ◽  
Diffusion Of Hydrogen

ABSTRACTFor plasma-grown a-Si:H films deposited at substrate temperatures between 100 and 580°C the diffusion of hydrogen was studied by SIMS profiling of H/D interdiffusion and by hydrogen evolution. The solubility for deuterium penetration into a-Si:H is found to be limited by the hydrogen concentration. Diffusion prefactors and activation energies evaluated for a constant diffusion length follow a Meyer-Neldel rule. The diffusion free energies obtained by interdiffusion and evolution experiments agree closely up to about 400°C but disagree at higher substrate temperatures.

Diffusion of Hydrogen in Titanium-Vanadium Alloys

2005 ◽  
Vol 237-240 ◽  
pp. 340-345 ◽  
Author(s):  
Hans Jürgen Christ ◽  
S. Schroers ◽  
F.H.S. dos Santos
Keyword(s):  
Diffusion Coefficient ◽  
Titanium Alloys ◽  
Hydrogen Concentration ◽  
Hydrogen Diffusion ◽  
High Strength ◽  
Vanadium Concentration ◽  
Vanadium Alloys ◽  
High Hydrogen ◽  
Hydrogen Diffusion Coefficient ◽  
Diffusion Of Hydrogen

β–titanium alloys are very attractive materials for many applications because they combine low density, high strength and excellent corrosion resistance. The available data indicate a much higher hydrogen diffusion coefficient in β–titanium alloys as compared to α and α + β alloys. In order to predict the range of applicability of β–titanium alloys in environments, which release hydrogen, the hydrogen diffusion coefficient (DH) needs to be known quantitatively. In the framework of this study the value of DH was determinated on samples, which were electrochemically hydrogen charged. Long thin rods were used as samples and charged in such a way that high hydrogen concentrations were obtained in one half of the length of the specimens, while the other half was kept virtually unaffected. After charging, the rods were annealed enabling hydrogen to diffuse. Hydrogen concentration profiles were experimentally determined and evaluated on the basis of the Matano technique, in order to reveal any effect of concentration on DH. The experiments were carried out on β–titanium alloys of the binary Ti–V system. The concentration range of vanadium in the alloys studied was selected in such a way that it represents the compositions commonly found in commercial alloys. The results show that the effect of hydrogen concentration on DH is negligible and that DH increases with the vanadium concentration.

Long Range Hydrogen Motion, Evolution, and Bonding in a-Si:H and a-Ge:H

1990 ◽  
Vol 192 ◽  
Author(s):  
R. Shinar ◽  
X.-L. Wu ◽  
S. Mitra ◽  
J. Shinar
Keyword(s):  
Structural Relaxation ◽  
Hydrogen Diffusion ◽  
Secondary Ion Mass Spectrometry ◽  
Diffusion Length ◽  
Diffusion Constant ◽  
Arrhenius Behavior ◽  
Ir Studies ◽  
Prolonged Annealing ◽  
Constant Diffusion ◽  
Secondary Ion

ABSTRACTThe results of secondary ion mass spectrometry and IR studies of hydrogen diffusion in a-Si:H and a-Ge:H are reviewed and discussed. In a-Si:H, the diffusion is significantly slower at low total H content. The exponent α of the power-law time dependent diffusion constant D(t) = Doo(ωt)−α does not decrease with temperature as 1-T/To. D(tL), for constant diffusion length L, thus deviates from an Arrhenius behavior. The “apparent” activation energy Ea and prefactor Do derived from lnD(tL) vs 1/T yield a Meyer-Neldel relation Do = Aooexp(Ea/kToo) irrespective of L, H content, or microstructure. Aoo ≅ 3.3 × 10−14cm2/s and Too ≅ 730K for 2.5 × 10−5 ≤ Do ≤ 102cm2/s and 1.3 ≤ Ea ≤ 2.2eV. The preliminary results on a-Ge:H are similar, with Aoo ≅ 1.3 × 10−15cm2/s and Too = 530K. It is suspected that deviations from an exponential distribution of H site energies, structural relaxation, and deep H trapping sites related to microvoids may all contribute to the deviation of α from a 1-T/To behavior. Measurements following prolonged annealing suggest structural relaxation that affects H-site energies.

High-Resolution Neutron Spectroscopy for the Investigation of Hydrogen Diffusion and Molecular Rotations in Solids

1993 ◽  
Vol 48 (1-2) ◽  
pp. 406-414
Author(s):  
T. Springer
Keyword(s):  
High Resolution ◽  
Hydrogen Diffusion ◽  
Quantum Effects ◽  
Quantum States ◽  
The Other ◽  
Neutron Spectroscopy ◽  
Impurity Atoms ◽  
Molecular Rotations ◽  
Rotational Motions ◽  
Diffusion Of Hydrogen

Abstract An introductory survey on applications of high-resolution neutron spectroscopy is presented, dealing with the motion of hydrogen in solids, namely concerning (i) random rotational motions or stationary tunneling states of NH+4-ions or CH3-groups, and (ii) diffusion of hydrogen in alloys. For the rotation of hydrogenous groups in solids, at higher temperatures rotational jumps can be found, whereas quantum states are observed by μeV-spectroscopy at temperatures below 50 K. On the other hand, hydrogen diffusion does not reveal pronounced evidence of quantum effects, except for hydrogen in a metal containing impurity atoms.

Diffusion and Effusion of Hydrogen in Microcrystalline Silicon

1997 ◽  
Vol 467 ◽  
Author(s):  
W. Beyer ◽  
P. Hapke ◽  
U. Zastrow
Keyword(s):  
Diffusion Coefficient ◽  
Infrared Absorption ◽  
Cyclotron Resonance ◽  
Hydrogen Diffusion ◽  
Electron Cyclotron Resonance ◽  
Microcrystalline Silicon ◽  
Hydrogen Diffusion Coefficient ◽  
Internal Surfaces ◽  
Substrate Temperatures ◽  
Hydrogen Effusion

ABSTRACTThe diffusion and effusion of hydrogen in hydrogenated microcrystalline silicon films deposited in an electron cyclotron resonance reactor were studied for various deposition temperatures Ts. For deposition temperatures below 250°C, hydrogen effusion is found to be dominated by desorption of hydrogen from internal surfaces followed by rapid out-diffusion of H2. Higher substrate temperatures result in an increased hydrogen stability suggesting the growth of a more compact material. For this latter type of samples, a hydrogen diffusion coefficient similar as in compact plasma-grown a-Si:H films is found despite a different predominant bonding of hydrogen according to infrared absorption.

Role of Hydrogen Microstructure in Amorphous Silicon

1992 ◽  
Vol 258 ◽  
Author(s):  
Sufi Zafar ◽  
E. A. Schiff
Keyword(s):  
Amorphous Silicon ◽  
Hydrogen Evolution ◽  
Hydrogen Diffusion ◽  
Hydrogenated Amorphous Silicon ◽  
Hydrogenated Amorphous ◽  
Unified Description

ABSTRACTA model for correlating the observed properties of hydrogenated amorphous silicon (a-Si:H) with the underlying hydrogen microstructure is reviewed. The model provides a unified description of defect equilibration, hydrogen evolution, rehydrogenation and hydrogen diffusion measurements.

Investigation of Hydrogen Diffusion Characteristics of the Heat Affected Zone of 2.25Cr-1Mo-0.25V Steel by an Electrochemical Permeation Method

2019 ◽  
Author(s):  
Xin Song ◽  
Zelin Han ◽  
Bin Liu ◽  
Mu Qin ◽  
Yuancai Duo ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Hydrogen Concentration ◽  
Heat Affected Zone ◽  
Hydrogen Diffusion ◽  
Trap Density ◽  
Hydrogen Diffusivity ◽  
Hydrogen Flux ◽  
Hydrogen Trap ◽  
Diffusion Characteristics ◽  
Effective Hydrogen

Abstract The heat affected zone (HAZ) of 2.25Cr-1Mo-0.25V welded joint is a critical part for the safety of hydrogenation reactors. Hydrogen has a significant effect on the HAZ, studying hydrogen diffusion characteristics, such as: hydrogen flux and the effective hydrogen diffusivity has a remarkable value in investigating the hydrogen-induced material degradation mechanisms. In this work, an electrochemical permeation method was applied to study the hydrogen diffusion characteristics of HAZ. Then, the metallographic microscope and a software “Image J” were used to analyze the density of grain boundaries of HAZ. The effect of the post–weld heat treatment (PWHT, i.e. annealing) on the hydrogen diffusion characteristics of HAZ was also been investigated. The results show that after PWHT, the effective hydrogen diffusivity of HAZ increases from 1.63 × 10−7cm2·s−1 to 3.68 × 10−7cm2·s−1, the hydrogen concentration decreases from 1.92 × 10−4mol·cm−3 to 1.09 × 10−4mol·cm−3, and the hydrogen trap density decreases from 3.00 × 1026m−3 to 0.76 × 1026m−3. Thus, PWHT can significantly reduce density of grain boundaries, thereby reducing the hydrogen trap density, enhancing the hydrogen diffusivity and reducing the hydrogen concentration.

scholarly journals Calculating the activation energies of nickel, manufactured using 3D printing technology, with multichannel hydrogen diffusion model

2019 ◽  
Vol 121 ◽  
pp. 04017
Author(s):  
Petr Zumberov ◽  
Sergey Kolesov ◽  
Vladimir Polyansky ◽  
Evgeniy Varshavchik
Keyword(s):  
3D Printing ◽  
Hydrogen Diffusion ◽  
Mathematic Model ◽  
Activation Energies ◽  
Modern World ◽  
Printing Technology ◽  
High Entropy ◽  
3D Printing Technology ◽  
3D Printed ◽  
Vacuum Heating

In modern world more and more materials with extreme properties are being used: high alloys, high-entropy alloys, nanostructured materials, etc. The extreme properties of these materials make them especially sensitive to hydrogen diffusion. Hydrogen can severely impair their properties and cause failures in structures and machines the material is used in. Nowadays, when structures and components are becoming increasingly complex, the use of 3D printing technology is becoming more widespread. Components made using 3D printing technologies are usually layered, which increase the amount of hydrogen that can diffuse into the material. The amount of hydrogen concentration in 3D printed nickel samples has been determined using vacuum heating method in hydrogen analyzer AV-1. The samples were held at different constant temperatures and the total amount of hydrogen extracted at those temperatures was calculated. A mathematic model was developed to evaluate the amount of hydrogen extracted at a given temperature. The evaluation was then compared to the experiment results, and the validity of the mathematical model and the selected hydrogen activation energies was verified.

Microscopic Study Of The Hydrogen Diffusion In III-V Semiconductors

1998 ◽  
Vol 513 ◽  
Author(s):  
A. Burchard ◽  
M. Deicher ◽  
D. Forkel-Wirth ◽  
M. Knopf ◽  
R. Magerle ◽  
...  
Keyword(s):  
Microscopic Study ◽  
Angular Correlation ◽  
Hydrogen Diffusion ◽  
Pac Spectroscopy ◽  
Microscopic Scale ◽  
First Results ◽  
Diffusion Of Hydrogen

ABSTRACTWe report on experiments which observe on a microscopic scale the migration of isolated hydrogen in InP, GaAs, and InAs. Using the radioactive acceptor 117Cd, Cd-H pairs have been formed in these III-V semiconductors. After the decay of 117Cd to 117In, H is no longer bound to an acceptor and can diffuse freely. This diffusion has been observed by perturbed yy angular correlation (PAC) spectroscopy. At 10 K, the occupation of two different lattice sites by hydrogen has been observed. First results on the diffusion of hydrogen will be discussed.

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