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.

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.

scholarly journals Hydrogen diffusion and the percolation of austenite in nanostructured bainitic steel

2014 ◽  
Vol 470 (2168) ◽  
pp. 20140108 ◽  
Author(s):  
L. C. D. Fielding ◽  
E. J. Song ◽  
D. K. Han ◽  
H. K. D. H. Bhadeshia ◽  
D.-W. Suh
Keyword(s):  
Hydrogen Diffusion ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Bainitic Ferrite ◽  
Effective Diffusivity ◽  
Steel Sample ◽  
Thin Plates ◽  
Heat Treated ◽  
Diffusion Of Hydrogen

The diffusion of hydrogen in austenite is slower than in ferrite. Experiments have been conducted to study the behaviour of hydrogen in a nanostructured steel sample consisting of a mixture of thin plates of bainitic ferrite and intervening films of retained austenite, with the latter phase present in a quantity larger than the percolation threshold, i.e. it has three-dimensional connectivity. The structure was then heat treated to control the fraction of austenite, and hence to study the role of hydrogen when the austenite decomposes below the value required to sustain percolation. The experiments have involved both thermal desorption analysis and permeation, and when combined with theoretical analysis, indicate a significant influence of percolating austenite in hindering the passage of hydrogen into the steel during hydrogen charging, and its permeation through the composite nanostructure. The effect is not as large as might be expected from a simple comparison of independent data on the diffusivities of hydrogen in the two lattices, because the effective diffusivity in ferrite is found to be much smaller than in the defect-free ferrite, owing to trapping effects. The morphology of the austenite is demonstrated to play a role by comparing with a sample containing a larger volume fraction of austenite but present as isolated grains which are ineffective to the permeation of hydrogen.

Pausing-time distribution of hydrogen diffusion in Gaussian distribution energy

2015 ◽  
Vol 29 (09) ◽  
pp. 1550059 ◽  
Author(s):  
Harumi Hikita ◽  
Kazuo Morigaki
Keyword(s):  
Diffusion Coefficient ◽  
Time Distribution ◽  
Hydrogen Diffusion ◽  
Diffusion Time ◽  
Density Of State ◽  
Gaussian Density ◽  
Log Normal ◽  
Distribution Energy ◽  
Log Normal Distribution ◽  
Diffusion Of Hydrogen

The pausing-time distribution of thermal diffusion of hydrogen is analytically shown in the Gaussian density of state. The pausing-time distribution exhibits a log-normal distribution. It has been shown that the pausing-time distribution follows approximately power law, i.e., t-1-α(t: pausing time). The diffusion coefficient of hydrogen is also obtained to be approximately τα-1 (τ: diffusion time). The value of α is the ratio of hydrogen temperature Tr to T2σ, in which T2σ, is a temperature corresponding to 2σ (σ: standard deviation). Finally, Brownian motion is shown to correspond to the case of σ = 0. The width of the energy distribution play an important role in hydrogen diffusion.

scholarly journals Hydrogen Diffusion and Its Effect on Hydrogen Embrittlement in DP Steels With Different Martensite Content

2020 ◽  
Vol 7 ◽  
Author(s):  
Zhen Wang ◽  
Jing Liu ◽  
Feng Huang ◽  
Yun-jie Bi ◽  
Shi-qi Zhang
Keyword(s):  
Hydrogen Embrittlement ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
Hydrogen Atoms ◽  
Martensite Content ◽  
Measurement Results ◽  
Dp Steels ◽  
Logarithmic Relationship ◽  
Diffusion Of Hydrogen ◽  
Effective Hydrogen

The hydrogen diffusion behavior and hydrogen embrittlement susceptibility of dual phase (DP) steels with different martensite content were investigated using the slow strain-rate tensile test and hydrogen permeation measurement. Results showed that a logarithmic relationship was established between the hydrogen embrittlement index (IHE) and the effective hydrogen diffusion coefficient (Deff). When the martensite content is low, ferrite/martensite interface behaves as the main trap that captures the hydrogen atoms. Also, when the Deff decreases, IHE increases with increasing martensite content. However, when the martensite content reaches approximately 68.3%, the martensite grains start to form a continuous network, Deff reaches a plateau and IHE continues to increase. This is mainly related to the reduction of carbon content in martensite and the length of ferrite/martensite interface, which promotes the diffusion of hydrogen atoms in martensite and the aggregation of hydrogen atoms at the ferrite/martensite interface. Finally, a model describing the mechanism of microstructure-driven hydrogen diffusion with different martensite distribution was established.

Selected applications of perturbed angular correlation of γ-rays (PAC) spectroscopy in biochemistry

2010 ◽  
pp. 255-267
Author(s):  
Lars Hemmingsen ◽  
Monika Stachura ◽  
Peter Waaben Thulstrup ◽  
Niels Johan Christensen ◽  
Karl Johnston
Keyword(s):  
Angular Correlation ◽  
Perturbed Angular Correlation ◽  
Pac Spectroscopy ◽  
Γ Rays

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.

scholarly journals Electrochemical Properties of La2Mg17/Ni Electrodes Prepared via TiF3-Catalysed Mechanical Milling

2015 ◽  
Vol 2015 ◽  
pp. 1-5
Author(s):  
T. Li ◽  
Z. Liu ◽  
G. Zhang ◽  
F. Ruan ◽  
R. Guo ◽  
...  
Keyword(s):  
Storage Capacity ◽  
Hydrogen Diffusion ◽  
High Energy ◽  
Electrochemical Reactions ◽  
Hydrogen Storage Capacity ◽  
Step Method ◽  
Maximum Value ◽  
Electrochemical Capacity ◽  
Energy Ball ◽  
Diffusion Of Hydrogen

In order to improve the hydrogen storage capacity of conventional La2Mg17electrode alloys, a nanocrystalline/amorphous-structured La2Mg17-Ni composite material was produced by high energy ball milling in the presence of TiF3. Subsequent analysis of the discharge/charge cycle performances of this electrode material revealed that its cycle stability and electrochemical capacity were greatly improved, with the latter reaching a maximum value of 787.07 mAh/g with optimisation of the TiF3addition. Moreover, a remarkable enhancement in the reversibility of electrochemical reactions on the material’s surface was also observed. Hydrogen diffusion coefficients for the material were calculated by means of a potential step method, confirming that TiF3markedly improves the long-range diffusion of hydrogen within the material.

Anwendung elektrochemischer Verfahren zur Untersuchung der Diffusion von Wasserstoff-Isotopen in V, Nb und Ta / Application of Electrochemical Techniques for Studying Diffusion of Hydrogen Isotopes in V, Nb and Ta

1976 ◽  
Vol 31 (7) ◽  
pp. 760-768
Author(s):  
N. Boes ◽  
H. Züchner
Keyword(s):  
Diffusion Process ◽  
Diffusion Coefficients ◽  
Hydrogen Diffusion ◽  
Tetrahedral Site ◽  
Electrochemical Techniques ◽  
Time Lag ◽  
Tetrahedral Sites ◽  
Dissolved Hydrogen ◽  
Strain Model ◽  
Diffusion Of Hydrogen

Abstract After suitable preparation (improvement) of samples H (D) -diffusion coefficients of V-, Nb-, and Ta-foils can be measured reliably at low H (D) -concentrations in the temperature range 0 to 100 °C by means of an electrochemical time-lag method. A modified strain model indicates that the tetrahedral sites in bcc lattices have to be taken as the stable positions for the dissolved hydrogen. The elementary jump in the diffusion process from one tetrahedral site to the next passes directly through a tetrahedral plane. This model describes qualitatively the experimental results concerning the sequence of the activation energies for hydrogen diffusion in the three Vb-metals [E(Ta)>E(Nb)>E(V)].

Diffusion of Hydrogen and Hydrogen-Dopant Interactions in Si Doped GaAs and GaAlAS Alloys

1992 ◽  
Vol 262 ◽  
Author(s):  
J. Chevallier ◽  
B. Machayekhi ◽  
C. Grattepain ◽  
R. Rahbi ◽  
B. Theys
Keyword(s):  
Doping Level ◽  
Hydrogen Diffusion ◽  
Alloy Composition ◽  
Diffusion Profile ◽  
Deep Acceptor ◽  
Vibrational Characteristics ◽  
Si Doped ◽  
Diffusion Of Hydrogen ◽  
Diffusion Profiles ◽  
Diffusion Properties

ABSTRACTDeactivation of silicon dopants by hydrogen in GaAs and GaAlAs proceeds through the formation of hydrogen-dopant complexes with thermodynamical and vibrational characteristics weakly sensitive to the alloy composition. However the hydrogen diffusion profile is strongly sensitive to the alloy composition. In GaAs:Si, the profile is an erfc function while in Ga1-xAlxAs:Si with x > xo, it is rather a step like function. From the doping level dependence of xo, we explain the hydrogen diffusion properties within a model where H° and H- govern the diffusion profiles respectively for x < xo and x > xo. We deduce that hydrogen behaves as a deep acceptor in these materials with a level slightly resonant in the conduction band of GaAs and localized in the band gap of Ga1-xAlxAs alloys for x > 0.07.

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