scholarly journals Hydrogen Trapping in bcc Iron

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2288 ◽  
Author(s):  
Anastasiia S. Kholtobina ◽  
Reinhard Pippan ◽  
Lorenz Romaner ◽  
Daniel Scheiber ◽  
Werner Ecker ◽  
...  
Keyword(s):  
Density Functional ◽  
Atomic Level ◽  
Body Centered Cubic ◽  
Hydrogen Trapping ◽  
Functional Theory ◽  
Bcc Iron ◽  
Ferromagnetic Body ◽  
Fundamental Understanding ◽  
Crystal Lattice Defects ◽  
Trapping Sites

Fundamental understanding of H localization in steel is an important step towards theoretical descriptions of hydrogen embrittlement mechanisms at the atomic level. In this paper, we investigate the interaction between atomic H and defects in ferromagnetic body-centered cubic (bcc) iron using density functional theory (DFT) calculations. Hydrogen trapping profiles in the bulk lattice, at vacancies, dislocations and grain boundaries (GBs) are calculated and used to evaluate the concentrations of H at these defects as a function of temperature. The results on H-trapping at GBs enable further investigating H-enhanced decohesion at GBs in Fe. A hierarchy map of trapping energies associated with the most common crystal lattice defects is presented and the most attractive H-trapping sites are identified.

scholarly journals Ab initio моделирование энергии растворения и энергии связи водорода с 3sp-, 3d- и 4d-примесями в ОЦК-железе

2021 ◽  
Vol 63 (7) ◽  
pp. 830
Author(s):  
М.С. Ракитин ◽  
А.А. Мирзоев
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Theoretical Description ◽  
Atomic Level ◽  
Functional Theory ◽  
Bcc Iron ◽  
Fundamental Understanding ◽  
Substitutional Impurities ◽  
Hydrogen Dissolution

A fundamental understanding of the localization of H atoms in steel is an important step towards a theoretical description of the mechanisms of hydrogen embrittlement at the atomic level. Ab initio calculations within the framework of density functional theory (DFT) is used to investigate the effect of various substitutional impurities Mg, Al, Si, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo , Pd and Cd on the energy of hydrogen dissolution in the lattice of bcc iron. The electronic and elastic contributions of various impurities to the dissolution energy are distinguished, and their influence on the binding energy of hydrogen and impurities is analyzed. The existence of a linear dependence of the energy of hydrogen dissolution on the magnitude of the change in the electron density of the intra-tetrahedral pore after the introduction of a hydrogen atom into it is shown. The results obtained made it possible to formulate the key mechanisms for controlling the localization of hydrogen in bcc iron by substitution impurities.

Migration Barriers and Evolution of Mechanical Properties of Oxide Nanoclusters Containing Helium

2015 ◽  
Vol 1743 ◽  
Author(s):  
Thomas Danielson ◽  
Celine Hin
Keyword(s):  
Mechanical Properties ◽  
Density Functional ◽  
Complex Oxide ◽  
Functional Theory ◽  
Ferritic Alloys ◽  
Helium Concentration ◽  
Migration Barriers ◽  
Bcc Iron ◽  
And Migration ◽  
Trapping Sites

ABSTRACTHigh number densities of complex oxide nanoclusters in nanostructured ferritic alloys have been shown to act as effective trapping sites for the transmutation product helium. Density functional theory has been used to investigate the evolution of the mechanical properties of oxide nanoclusters as helium concentration increases. The migration barrier and migration path of helium in the oxide has also been tested in order to make a comparison with the barriers in BCC iron and offer insight to the helium trapping mechanisms of the oxides.

scholarly journals Evidence of hydrogen trapping at second phase particles in zirconium alloys

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Christopher Jones ◽  
Vidur Tuli ◽  
Zaheen Shah ◽  
Mhairi Gass ◽  
Patrick A. Burr ◽  
...  
Keyword(s):  
Density Functional ◽  
Secondary Ion Mass Spectrometry ◽  
Zirconium Alloys ◽  
Nuclear Industry ◽  
Second Phase ◽  
Hydrogen Trapping ◽  
Functional Theory ◽  
Second Phase Particles ◽  
Hydrogen Isotope Ratios ◽  
Dft Modelling

AbstractZirconium alloys are used in safety–critical roles in the nuclear industry and their degradation due to ingress of hydrogen in service is a concern. In this work experimental evidence, supported by density functional theory modelling, shows that the α-Zr matrix surrounding second phase particles acts as a trapping site for hydrogen, which has not been previously reported in zirconium. This is unaccounted for in current models of hydrogen behaviour in Zr alloys and as such could impact development of these models. Zircaloy-2 and Zircaloy-4 samples were corroded at 350 °C in simulated pressurised water reactor coolant before being isotopically spiked with 2H2O in a second autoclave step. The distribution of 2H, Fe and Cr was characterised using nanoscale secondary ion mass spectrometry (NanoSIMS) and high-resolution energy dispersive X-ray spectroscopy. 2H− was found to be concentrated around second phase particles in the α-Zr lattice with peak hydrogen isotope ratios of 2H/1H = 0.018–0.082. DFT modelling confirms that the hydrogen thermodynamically favours sitting in the surrounding zirconium matrix rather than within the second phase particles. Knowledge of this trapping mechanism will inform the development of current understanding of zirconium alloy degradation through-life.

scholarly journals Interaction of sulfur with impurities in bcc iron

2021 ◽  
Vol 2103 (1) ◽  
pp. 012071
Author(s):  
A V Verkhovykh ◽  
A A Mirzoev ◽  
Yu K Okishev ◽  
N S Dyuryagina
Keyword(s):  
Density Functional Theory ◽  
Software Package ◽  
Density Functional ◽  
Functional Theory ◽  
The Third ◽  
Bcc Iron ◽  
The Density Functional Theory ◽  
Coordination Spheres ◽  
Strong Repulsion ◽  
Substitutional Impurities

Abstract In this work, the modeling of the sulfur interaction with substitutional impurities (Mn, P) and interstitial (C) has been carried out. All calculations were performed using the density functional theory in the WIEN2k software package. For the first two coordination spheres, there is a strong repulsion between carbon and sulfur, but in the third relative position, a slight attraction arises between the atoms. When sulfur interacts with manganese, attraction occurs only for the first coordination sphere, while the dissolution energy of both manganese and sulfur decreases. In the case of the S-P interaction, the binding energy is negative, and the dissolution energy of both sulfur and phosphorus decreases for all configurations, although the distance between phosphorus and sulfur increases. It can be assumed that the presence of phosphorus leads to the accumulation of sulfur in the material.

Hydrogen trapping in MAX phase Ti 3 SiC 2 : Insight from chemical bonding by density functional theory

2017 ◽  
Vol 118 (4) ◽  
pp. 47002 ◽  
Author(s):  
H. F. Zhang ◽  
X. L. Ren ◽  
J. Y. Zhang ◽  
J. Huang ◽  
C. H. Xu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Chemical Bonding ◽  
Density Functional ◽  
Max Phase ◽  
Hydrogen Trapping ◽  
Functional Theory

scholarly journals Quantum plasmonics: from jellium models to ab initio calculations

Nanophotonics ◽  
2016 ◽  
Vol 5 (3) ◽  
pp. 409-426 ◽  
Author(s):  
Alejandro Varas ◽  
Pablo García-González ◽  
Johannes Feist ◽  
F.J. García-Vidal ◽  
Angel Rubio
Keyword(s):  
Ab Initio ◽  
Density Functional ◽  
Plasmonic Nanostructures ◽  
Functional Theory ◽  
Fundamental Understanding ◽  
Invaluable Tool ◽  
Classical Models ◽  
Light Matter Interaction ◽  
Experimental Findings ◽  
The Impact

AbstractLight-matter interaction in plasmonic nanostructures is often treated within the realm of classical optics. However, recent experimental findings show the need to go beyond the classical models to explain and predict the plasmonic response at the nanoscale. A prototypical system is a nanoparticle dimer, extensively studied using both classical and quantum prescriptions. However, only very recently, fully ab initio time-dependent density functional theory (TDDFT) calculations of the optical response of these dimers have been carried out. Here, we review the recent work on the impact of the atomic structure on the optical properties of such systems. We show that TDDFT can be an invaluable tool to simulate the time evolution of plasmonic modes, providing fundamental understanding into the underlying microscopical mechanisms.

scholarly journals Interfacial Acidity on Oxide Surfaces: A Scaling Paradigm and the Role of the Hydrogen Bond

2020 ◽  
Author(s):  
Robert Chapleski ◽  
Azhad U. Chowdhury ◽  
Kyle Mason ◽  
Robert Sacci ◽  
Benjamin Doughty ◽  
...  
Keyword(s):  
Density Functional ◽  
Critical Role ◽  
Surface Interactions ◽  
Van Der Waals Interactions ◽  
Chemical Transformations ◽  
Acid Base ◽  
Functional Theory ◽  
Fundamental Understanding ◽  
Molecule Surface

<p><a></a>A fundamental understanding of acidity at an interface, as mediated by structure and molecule-surface interactions, is essential to elucidate the mechanisms of a range of chemical transformations. While the strength­­­­ of an acid in the gas and solution phases is conceptually well understood, how acid-base chemistry works at an interface is notoriously more complicated. Using density functional theory and nonlinear vibrational spectroscopy, we have developed a method to determine the interfacial Brønsted-Lowry acidity of aliphatic alcohols adsorbed on the {100} surface of the model perovskite, strontium titanate. Here we show that, while shorter and less branched alkanols are less acidic as a gas and more acidic in solution, shorter alcohols are less acidic whereas less substituted alkanols are more acidic at the gas-surface interface. Hydrogen bonding plays a critical role in defining acidity, whereas structure-acidity relationships are dominated by van der Waals interactions between the alcohol and the surface.</p><p><a></a></p><p> </p>

Interfacial Acidity on Oxide Surfaces: A Scaling Paradigm and the Role of the Hydrogen Bond

2020 ◽  
Author(s):  
Robert Chapleski ◽  
Azhad U. Chowdhury ◽  
Kyle Mason ◽  
Robert Sacci ◽  
Benjamin Doughty ◽  
...  
Keyword(s):  
Density Functional ◽  
Critical Role ◽  
Surface Interactions ◽  
Van Der Waals Interactions ◽  
Chemical Transformations ◽  
Acid Base ◽  
Functional Theory ◽  
Fundamental Understanding ◽  
Molecule Surface

<p><a></a>A fundamental understanding of acidity at an interface, as mediated by structure and molecule-surface interactions, is essential to elucidate the mechanisms of a range of chemical transformations. While the strength­­­­ of an acid in the gas and solution phases is conceptually well understood, how acid-base chemistry works at an interface is notoriously more complicated. Using density functional theory and nonlinear vibrational spectroscopy, we have developed a method to determine the interfacial Brønsted-Lowry acidity of aliphatic alcohols adsorbed on the {100} surface of the model perovskite, strontium titanate. Here we show that, while shorter and less branched alkanols are less acidic as a gas and more acidic in solution, shorter alcohols are less acidic whereas less substituted alkanols are more acidic at the gas-surface interface. Hydrogen bonding plays a critical role in defining acidity, whereas structure-acidity relationships are dominated by van der Waals interactions between the alcohol and the surface.</p><p><a></a></p><p> </p>

Surface modeling of photocatalytic materials for water splitting

2021 ◽  
Author(s):  
Chunyang Zhang ◽  
Guijun Chen ◽  
Yitao Si ◽  
Maochang Liu
Keyword(s):  
Density Functional Theory ◽  
Water Splitting ◽  
First Principles ◽  
Density Functional ◽  
Photocatalytic Property ◽  
Surface Modeling ◽  
Atomic Level ◽  
Functional Theory ◽  
Surface Configuration ◽  
Photocatalytic Reactions

Photocatalyst surface is central to photocatalytic reactions. The challenge is to explicitly understand both the surface configuration and the structure-dependent photocatalytic property at the atomic level. First-principles density functional theory...

Electronic structure and doping effect of Ni and Co in the kink on the edge dislocation of bcc iron

2007 ◽  
Vol 261-262 ◽  
pp. 37-46 ◽  
Author(s):  
Li Qun Chen ◽  
Zheng Chen Qiu
Keyword(s):  
Electronic Structure ◽  
Impurity Atom ◽  
Edge Dislocation ◽  
First Principles ◽  
Density Functional ◽  
Functional Theory ◽  
Discrete Variational Method ◽  
Solid Solution Softening ◽  
Bcc Iron ◽  
3D Impurities

Using the first-principles self-consistent discrete variational method based upon density functional theory, we investigated the energetics and the electronic structure of the 3d impurities Ni and Co in a kink on the [100](010) edge dislocation (ED) in bcc iron. The calculated results show that the interatomic energies between the impurity atom and the neighboring host atoms decrease. The bonding for the impurity atom (Ni, Co) and the neighboring host Fe atoms is weaker than that for an Fe atom at the X site and the corresponding atoms in the clean kink. These results indicate that sideways motion of the kink in the <100>{010} ED is accelerated by an impurity atom such as Ni or Co and that, consequently, the presence of impurities increases the dislocation mobility, thus leading to solid-solution softening.

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