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.

A complete ab initio thermodynamic and kinetic catalogue of the defect chemistry of hematite α-Fe2O3, its cation diffusion, and sample donor dopants

2021 ◽  
Author(s):  
Shehab Shousha ◽  
Sarah Khalil ◽  
Mostafa Youssef
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Defect Formation ◽  
Defect Chemistry ◽  
Cation Diffusion ◽  
Functional Theory ◽  
Migration Barriers ◽  
Hubbard U ◽  
And Migration ◽  
Formation Energies

This paper studies comprehensively the defect chemistry and cation diffusion in α-Fe2O3. Defect formation energies and migration barriers are calculated using density functional theory with a theoretically calibrated Hubbard U...

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.

Ab-Initio Study of Boron Diffusion Retardation in Si1-xGex

2006 ◽  
Vol 912 ◽  
Author(s):  
Yonghyun Kim ◽  
Taras A. Kirichenko ◽  
Sanjay K. Banerjee ◽  
Gyeong S. Hwang
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Density Functional Theory Calculation ◽  
Boron Diffusion ◽  
Ab Initio Study ◽  
Functional Theory ◽  
Migration Barriers ◽  
And Migration ◽  
Theory Calculation ◽  
And Diffusion

AbstractWe study B diffusion in the presence of Ge by using a first principles density functional theory calculation. We investigate the relative stability and migration barriers of Si and Ge interstitials as well as binding energy and diffusion pathway of Boron-Interstitial (BI) pair comprised of Boron and Si or Ge interstitials. We find that Ge interstitials are more stable but less mobile compared to Si interstitials, leading to higher population of interstitials in the implanted Si1-xGex. However, BI pair comprised of Ge interstitial and Boron is less stable compared to Si interstitial –Boron pair and migration barrier of BI pair in presence of Ge is increased, leading to less TED.

Helium Interaction with Y2Ti2O7: A First Principles Study

2014 ◽  
Vol 1645 ◽  
Author(s):  
Thomas Danielson ◽  
Celine Hin
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Great Promise ◽  
Functional Theory ◽  
Ferritic Alloys ◽  
Helium Bubbles ◽  
Helium Clusters ◽  
Helium Embrittlement ◽  
Materials Used ◽  
Trapping Sites

ABSTRACTHelium embrittlement poses a great threat to materials used in both fusion and fissionreactor systems due to (n,α) transmutation reactions. Because of this, materials capable of moderating the helium content reaching grain boundaries and voids must be developed and improved to prevent catastrophic failure of reactor materials. Nanostructured ferritic alloys (NFAs) have shown great promise in preventing helium embrittlement due to the large number density of nanoscale precipitates acting as trapping sites for helium clusters and helium bubbles. In this study, we present density functional theory calculations on the interaction of helium with nanoscale precipitates found in NFAs as a preliminary study to furthering our understanding of the energetic mechanisms causing the precipitates to act as trapping sites for helium.

Ab Initio Calculation of Mechanical Properties of Stacking Fault in 3C-SiC: Effect of Stress and Doping

2012 ◽  
Vol 717-720 ◽  
pp. 415-418
Author(s):  
Yoshitaka Umeno ◽  
Kuniaki Yagi ◽  
Hiroyuki Nagasawa
Keyword(s):  
Mechanical Properties ◽  
Ab Initio ◽  
Density Functional ◽  
Stacking Faults ◽  
Single Layer ◽  
Local Strain ◽  
Density Functional Theory Calculations ◽  
Stacking Fault ◽  
Functional Theory ◽  
N Doping

We carry out ab initio density functional theory calculations to investigate the fundamental mechanical properties of stacking faults in 3C-SiC, including the effect of stress and doping atoms (substitution of C by N or Si). Stress induced by stacking fault (SF) formation is quantitatively evaluated. Extrinsic SFs containing double and triple SiC layers are found to be slightly more stable than the single-layer extrinsic SF, supporting experimental observation. Effect of tensile or compressive stress on SF energies is found to be marginal. Neglecting the effect of local strain induced by doping, N doping around an SF obviously increase the SF formation energy, while SFs seem to be easily formed in Si-rich SiC.

First principles analysis of oxygen vacancy formation and migration in Sr2BMoO6 (B = Mg, Co, Ni)

RSC Advances ◽  
2016 ◽  
Vol 6 (38) ◽  
pp. 31968-31975 ◽  
Author(s):  
Shuai Zhao ◽  
Liguo Gao ◽  
Chunfeng Lan ◽  
Shyam S. Pandey ◽  
Shuzi Hayase ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Oxygen Vacancy ◽  
First Principles ◽  
Density Functional ◽  
Dft Method ◽  
Double Perovskites ◽  
Functional Theory ◽  
Oxygen Vacancy Formation ◽  
The Density Functional Theory ◽  
And Migration

In this work, we present a detailed first-principles investigation on the stoichiometric and oxygen-deficient structures of double perovskites, Sr2BMoO6 (B = Mg, Co and Ni), using the density functional theory (DFT) method.

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.

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