scholarly journals First-Principles Investigation of Atomic Hydrogen Adsorption and Diffusion on/into Mo-doped Nb (100) Surface

2018 ◽  
Vol 8 (12) ◽  
pp. 2466 ◽  
Author(s):  
Yang Wu ◽  
Zhongmin Wang ◽  
Dianhui Wang ◽  
Jiayao Qin ◽  
Zhenzhen Wan ◽  
...  
Keyword(s):  
First Principles ◽  
Atomic Hydrogen ◽  
Energy Barrier ◽  
Hydrogen Adsorption ◽  
Hydrogen Permeation ◽  
Diffusion Path ◽  
Interstitial Site ◽  
Octahedral Interstitial Site ◽  
Tetrahedral Interstitial Site ◽  
And Diffusion

To investigate Mo doping effects on the hydrogen permeation performance of Nb membranes, we study the most likely process of atomic hydrogen adsorption and diffusion on/into Mo-doped Nb (100) surface/subsurface (in the Nb12Mo4 case) via first-principles calculations. Our results reveal that the (100) surface is the most stable Mo-doped Nb surface with the smallest surface energy (2.75 J/m2). Hollow sites (HSs) in the Mo-doped Nb (100) surface are H-adsorption-favorable mainly due to their large adsorption energy (−4.27 eV), and the H-diffusion path should preferentially be HS→TIS (tetrahedral interstitial site) over HS→OIS (octahedral interstitial site) because of the correspondingly lower H-diffusion energy barrier. With respect to a pure Nb (100) surface, the Mo-doped Nb (100) surface has a smaller energy barrier along the HS→TIS pathway (0.31 eV).

scholarly journals Influence of Nickel Addition on the Stability, Trapping, and Diffusion Behaviour of Hydrogen in Vanadium: A First-Principles Investigation

2021 ◽  
Author(s):  
Jiayao Qin ◽  
Zhigao Liu ◽  
Wei Zhao ◽  
Dianhui Wang ◽  
Yanli Zhang ◽  
...  
Keyword(s):  
First Principles ◽  
Effective Means ◽  
Interstitial Site ◽  
First Principles Calculation ◽  
Hydrogen Energy ◽  
Ni Doping ◽  
Octahedral Interstitial Site ◽  
The Stability ◽  
And Diffusion ◽  
Diffusion Behaviour

Abstract Hydrogen embrittlement causes deterioration of materials used in hydrogen energy systems. Alloying is an effective means for overcoming this issue. In this study, the first-principles calculation method was used to investigate the effects of alloying Ni on the stability, dissolution, trapping, and diffusion behaviour of interstitial/vacancy H atoms in V. The calculated phonon spectra and solution energies of the vacancy/interstitial H atoms revealed that the V–Ni phase was dynamically and thermodynamically stable, and Ni addition could reduce the stability of V hydrides and improve their resistance to H embrittlement. H atoms in the interstitials and vacancies preferentially occupied the tetrahedral interstitial site (TIS) and octahedral interstitial site (OIS) with the lowest solution energies and diffused along the TIS → TIS and OIS → OIS paths with the minimum diffusion barrier energies. The trapping energy of the vacancy H atoms indicated that the addition of Ni could reduce the H trapping capability of the vacancies and suppress the retention of H in V. Detailed analysis of the calculated H diffusion barriers indicated that the presence of monovacancy defects blocked the diffusion of H atoms more than the presence of interstitials, and Ni doping did not enhance the H diffusion coefficient.

Atomic Hydrogen in GaN

1995 ◽  
Vol 378 ◽  
Author(s):  
Jürg Neugebauer ◽  
Chris G. Van de Walle
Keyword(s):  
Electronic Structure ◽  
Nitrogen Atom ◽  
Total Energy ◽  
Diffusion Barrier ◽  
First Principles ◽  
Atomic Hydrogen ◽  
Interstitial Site ◽  
Energy Calculations ◽  
Tetrahedral Interstitial Site ◽  
Cubic Gan

ABSTRACTBased on extensive first-principles total-energy calculations we study the electronic structure, atomic geometry and energetics of atomic hydrogen in cubic GaN. All charge states of hydrogen (H+, H0, H-) are examined. For H- the gallium tetrahedral interstitial site is energetically most stable. All other sites are much higher in energy, indicating a high diffusion barrier for H- in GaN. H+ favors positions on a sphere with a radius of ≈ 1 Å and a nitrogen atom in the center. Among these positions the nitrogen antibonding site is energetically most stable. An unexpectedly large negative-U effect (U = —2.5eV) indicates that H0 is unstable.

scholarly journals Hydrogen Transportation Behaviour of V–Ni Solid Solution: A First-Principles Investigation

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2603
Author(s):  
Jiayao Qin ◽  
Zhigao Liu ◽  
Wei Zhao ◽  
Dianhui Wang ◽  
Yanli Zhang ◽  
...  
Keyword(s):  
First Principles ◽  
Interstitial Site ◽  
Ni Doping ◽  
Octahedral Interstitial Site ◽  
Ni Addition ◽  
Solution Energy ◽  
Tetrahedral Interstitial Site ◽  
Materials Used ◽  
The Stability ◽  
Hydrogen Systems

Hydrogen embrittlement causes deterioration of materials used in metal–hydrogen systems. Alloying is a good option for overcoming this issue. In the present work, first-principles calculations were performed to systematically study the effects of adding Ni on the stability, dissolution, trapping, and diffusion behaviour of interstitial/vacancy H atoms of pure V. The results of lattice dynamics and solution energy analyses showed that the V–Ni solid solutions are dynamically and thermodynamically stable, and adding Ni to pure V can reduce the structural stability of various VHx phases and enhance their resistance to H embrittlement. H atoms preferentially occupy the characteristic tetrahedral interstitial site (TIS) and the octahedral interstitial site (OIS), which are composed by different metal atoms, and rapidly diffuse along both the energetically favourable TIS → TIS and OIS → OIS paths. The trapping energy of monovacancy H atoms revealed that Ni addition could help minimise the H trapping ability of the vacancies and suppress the retention of H in V. Monovacancy defects block the diffusion of H atoms more than the interstitials, as determined from the calculated H-diffusion barrier energy data, whereas Ni doping contributes negligibly toward improving the H-diffusion coefficient.

Effect of Boron and Hydrogen on the Electronic Structure of Ni3Al

1993 ◽  
Vol 319 ◽  
Author(s):  
N. Kioussis ◽  
H. Watanabe ◽  
R.G. Hemker ◽  
W. Gourdin ◽  
A. Gonis ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Charge Density ◽  
First Principles ◽  
Electronic Structure Calculations ◽  
Interstitial Site ◽  
Octahedral Interstitial Site ◽  
Interstitial Region ◽  
Ordered Intermetallic ◽  
Lmto Method ◽  
Structure Calculations

AbstractUsing first-principles electronic structure calculations based on the Linear-Muffin-Tin Orbital (LMTO) method, we have investigated the effects of interstitial boron and hydrogen on the electronic structure of the L12 ordered intermetallic Ni3A1. When it occupies an octahedral interstitial site entirely coordinated by six Ni atoms, we find that boron enhances the charge distribution found in the strongly-bound “pure” Ni3AI crystal: Charge is depleted at Ni and Al sites and enhanced in interstitial region. Substitution of Al atoms for two of the Ni atoms coordinating the boron, however, reduces the interstitial charge density between certain atomic planes. In contrast to boron, hydrogen appears to deplete the interstitial charge, even when fully coordinated by Ni atoms. We suggest that these results are broadly consistent with the notion of boron as a cohesion enhancer and hydrogen as an embrittler.

First-principles investigation of copper diffusion barrier performance in defective 2D layered materials

2022 ◽  
Author(s):  
Manareldeen Ahmed ◽  
Yan Li ◽  
Wenchao Chen ◽  
Erping Li
Keyword(s):  
Barrier Layer ◽  
Diffusion Barrier ◽  
First Principles ◽  
Energy Barrier ◽  
2D Materials ◽  
Diffusion Path ◽  
Layered Materials ◽  
Vacancy Defects ◽  
2D Layered Materials ◽  
Barrier Performance

Abstract This paper investigates the diffusion barrier performance of 2D layered materials with pre-existing vacancy defects using first-principles density functional theory. Vacancy defects in 2D materials may give rise to a large amount of Cu accumulation, and consequently, the defect becomes a diffusion path for Cu. Five 2D layered structures are investigated as diffusion barriers for Cu, i.e., graphene with C vacancy, hBN with B/N vacancy, and MoS2 with Mo/2S vacancy. The calculated energy barriers using climbing image - nudged elastic band show that MoS2-V2S has the highest diffusion energy barrier among other 2D layers, followed by hBN-VN and graphene. The obtained energy barrier of Cu on defected layer is found to be proportional to the length of the diffusion path. Moreover, the diffusion of Cu through vacancy defects is found to modulate the electronic structures and magnetic properties of the 2D layer. The charge density difference shows that there exists a considerable charge transfer between Cu and barrier layer as quantified by Bader charge. Given the current need for an ultra-thin diffusion barrier layer, the obtained results contribute to the field of application of 2D materials as Cu diffusion barrier in the presence of mono-vacancy defects.

Effects of boron on the mechanical properties of the TiAl–Ti3Al alloy: A first-principles investigation

2017 ◽  
Vol 31 (02) ◽  
pp. 1750002
Author(s):  
Zhong-Zhu Li ◽  
Ye Wei ◽  
Hong-Bo Zhou ◽  
Guang-Hong Lu
Keyword(s):  
Mechanical Properties ◽  
First Principles ◽  
Phase Interface ◽  
Interstitial Site ◽  
Site Preference ◽  
Al Alloy ◽  
Octahedral Interstitial Site ◽  
Binary Phase ◽  
Negative Effect ◽  
Energy Formula

Employing a first-principles method in combination with the empirical criterions, we have investigated the site preference of boron (B) and its effect on the mechanical properties of the binary-phase TiAl–Ti3Al alloy. It is found that B energetically prefers to occupy the Ti-rich octahedral interstitial site, because B is more favorable to bond with Ti in comparison with Al. The occupancy tendency of B in the TiAl–Ti3Al alloy is the TiAl/Ti3Al interface [Formula: see text] Ti3Al [Formula: see text] TiAl, thus B tends to segregate into the binary-phase interface in the TiAl–Ti3Al alloy. The charge density difference shows that B at the TiAl–Ti3Al interface will form strong B–Ti bonds and weak B–Al bonds, leading to the significant increasing of the cleavage energy [Formula: see text] and the unstable stacking fault energy [Formula: see text]. This indicates that the presence of B will strengthen the TiAl/Ti3Al interface, but block its mobility. Further, the ratio of [Formula: see text]/[Formula: see text] of the B-doped system is 4.63%, 8.19% lower than that of the clean system. Based on the empirical criterions, B will have a negative effect on the ductility of the TiAl–Ti3Al alloy.

Rate Theory Modeling of Irradiation-induced Phosphorus Segregation in FCC nickel Using First Principles Calculations

2008 ◽  
Vol 1125 ◽  
Author(s):  
Ken-ichi Ebihara ◽  
Masatake Yamaguchi ◽  
Hideo Kaburaki ◽  
Yutaka Nishiyama
Keyword(s):  
First Principles ◽  
Interstitial Site ◽  
Theory Model ◽  
First Principles Calculation ◽  
Rate Theory ◽  
Vacancy Mechanism ◽  
First Principles Calculations ◽  
Phosphorus Segregation ◽  
Octahedral Interstitial Site ◽  
P Distribution

ABSTRACTWe have evaluated phosphorus (P) segregation in ion-irradiated nickel (Ni) by the rate theory model incorporating the results of first principles calculations. We find from our first principles calculation that the transport of P via the rotation mode of a mixed-dumbbell is unlikely to occur, and the transport coefficient of phosphorus by the vacancy mechanism is much larger than that reported previously. On the basis of our first principles results, we have also proposed to include the effect of free migration of P via the octahedral interstitial site of FCC Ni crystal in the rate theory model. With all these renewed parameters, we have successfully obtained the P distribution in irradiated Ni, which is very close to experiment, by adjusting the effect of P transport by the vacancy mechanism.

Hydrogen Adsorption and Diffusion on the Anatase TiO2(101) Surface: A First-Principles Investigation

2011 ◽  
Vol 115 (14) ◽  
pp. 6809-6814 ◽  
Author(s):  
Mazharul M. Islam ◽  
Monica Calatayud ◽  
Gianfranco Pacchioni
Keyword(s):  
First Principles ◽  
Hydrogen Adsorption ◽  
Anatase Tio2 ◽  
And Diffusion

SITE PREFERENCE AND ELASTIC PROPERTIES OF A2-Ti3Al WITH OXYGEN IMPURITY: A FIRST-PRINCIPLES STUDY

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2749-2755 ◽  
Author(s):  
YE WEI ◽  
YING ZHANG ◽  
GUANG-HONG LU ◽  
HUIBIN XU
Keyword(s):  
Elastic Properties ◽  
First Principles ◽  
Density Functional ◽  
Interstitial Site ◽  
Site Preference ◽  
Oxygen Impurity ◽  
Functional Theory ◽  
Octahedral Interstitial Site ◽  
Tial Alloys ◽  
The Density Functional Theory

We employed a first-principles method based on the density functional theory to investigate the effect of impurity O on the site preference and elastic properties of α2- Ti 3 Al . We found that the O atom prefers to occupy the Ti -rich octahedral interstitial site in α2- Ti 3 Al . We calculated the elastic constants of α2- Ti 3 Al with single O atom, which demonstrate that the O presence has no large effect on α2- Ti 3 Al according to the empirical criterions. Other factors such as O cluster should be taken into account to understand the deleterious effect of O on α2- Ti 3 Al . Our results provide a useful reference to further study the mechanical properties of TiAl alloys.

scholarly journals Investigation of the dissolution and diffusion properties of interstitial oxygen at grain boundaries in body-centered-cubic iron by the first-principles study

RSC Advances ◽  
2021 ◽  
Vol 11 (15) ◽  
pp. 8643-8653
Author(s):  
Zhijie Liu ◽  
Yange Zhang ◽  
Xiangyan Li ◽  
Yichun Xu ◽  
Xuebang Wu ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
First Principles ◽  
Energy Barrier ◽  
High Energy ◽  
Low Energy ◽  
Interstitial Oxygen ◽  
Body Centered Cubic ◽  
High Energy Barrier ◽  
And Diffusion ◽  
Diffusion Properties

Oxygen atoms prefer to segregate to grain boundaries (2/2′). They segregate to Σ3〈110〉(111) with low energy barrier, but concentrate at the transition region of Σ5〈001〉(310) due to high energy barrier. They diffuse in grain boundaries (3/3′) more than in bulk (1/1′).

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