A5071189619- Fusion materials and technologies
- Nuclear Materials and Properties
- Magnetic properties of thin films
- Microstructure and Mechanical Properties of Steels
- High Temperature Alloys and Creep
- Advanced Chemical Physics Studies
- Microstructure and mechanical properties
- Magnetic Properties and Applications
- Hydrogen embrittlement and corrosion behaviors in metals
- nanoparticles nucleation surface interactions
- Theoretical and Computational Physics
- Advanced Materials Characterization Techniques
- Semiconductor materials and devices
- Perfectionism, Procrastination, Anxiety Studies
- Semiconductor materials and interfaces
- Rare-earth and actinide compounds
- Intermetallics and Advanced Alloy Properties
- Nuclear reactor physics and engineering
- Surface and Thin Film Phenomena
- High-pressure geophysics and materials
- Ion-surface interactions and analysis
- Graphene research and applications
- Hydrogen Storage and Materials
- Machine Learning in Materials Science
- Nuclear materials and radiation effects
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2015-2024
Université Paris-Saclay
2016-2024
CEA Paris-Saclay
2013-2024
Centre National de la Recherche Scientifique
2003-2021
Fayetteville State University
2020
Beijing Haidian Hospital
2019
Direction des énergies
2007-2016
University of Missouri
2008-2014
CEA Paris-Saclay - Etablissement de Saclay
2007-2011
Centre Interdisciplinaire de Nanoscience de Marseille
2004
Density functional theory calculations have been performed to study the dissolution and migration of helium in $\ensuremath{\alpha}$-iron, stability small helium-vacancy clusters ${\mathrm{He}}_{n}{V}_{m}$ ($n$,$m=0$ 4). Substitutional interstitial configurations are found similar stabilities. The tetrahedral configuration is more stable than octahedral by 0.2 eV. Interstitial atoms predicted attractive interactions a very low energy (0.06 eV), suggesting that He bubbles can form at...
We report a detailed ab initio study of the stability and migration self-interstitial atoms (SIAs) di-interstitials (di-SIAs) in $\ensuremath{\alpha}$-Fe. The $⟨110⟩$ dumbbell is confirmed to be most stable SIA configuration, 0.7 eV below $⟨111⟩$ dumbbell. lowest-energy path corresponds nearest-neighbor translation-rotation jump with barrier 0.34 eV. configuration for di-SIAs consists parallel dumbbells. Their mechanism similar that SIAs, an activation energy 0.42 These results are at...
We present Monte Carlo simulations of the first stages coherent precipitation copper in $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Fe}$. Our method is based on a vacancy mediated diffusion model, which takes into account dependence concentrations and migration barriers local atomic environment. These parameters are fitted to ab initio data, calculated within density functional theory. The simulated kinetics compared with experimental one. Fe-Cu system characterized by low mutual...
We present an atomistic study of the behavior and interactions hydrogen vacancies in body centered cubic (bcc) iron, using both ab initio classical molecular dynamics methods. Hydrogen causes damage to materials through embrittlement, hardening, swelling; we investigate role these processes. Hydrogen, which normally diffuses with a very small barrier, is strongly trapped at monovacancies vacancy clusters, resulting changes its electronic structure. Following saturation surface cluster,...
This is the first study to empirically identify distinct acculturative adjustment patterns of new international students over their 3 semesters in United States. The sample consisted 507 Chinese studying Using psychological distress as an indicator adjustment, measured 4 time points (prearrival, semester, second and third semester), groups student trajectories emerged: (a) a group exhibiting high levels across each point (consistently distressed; 10%), (b) with decreasing scores from Time 1...
The diffusion of He in irradiated $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Fe}$ is studied using a rate theory model addressing the effect impurities. Ab initio values for migration and binding energies He, He-vacancy complexes, vacancy, self-interstitial clusters are used to desorption experiments He-implanted $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Fe}$. Using brute ab data yields significant discrepancy with experimental measurements. On other hand, good agreement...
The interplay between vacancies ($V$) and interstitial solutes $X$ ($X=\text{C}$, N, O) its impact on thermodynamic properties of $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Fe}$ solid solutions are studied, starting from first principles calculations. A systematic comparison the three is performed, investigating $X--\mathrm{Fe}$, $X$--$X$, $V$--$X$ interactions. In lattice, strength $X--\mathrm{Fe}$ interactions found to govern dissolution properties. Next vacancies, competition solute...
The decomposition of Fe-Cr solid solutions during thermal aging is modeled by atomistic kinetic Monte Carlo simulations, using a rigid lattice approximation with pair interactions that depend on the local composition and temperature. are fitted ab initio calculations mixing energies vacancy migration barriers at 0 K. entropic contributions to alloys formation free taken into account. model reproduces change in sign energy alloy gives realistic thermodynamic properties, including an...
In addition to the eight conventional high-symmetry configurations for self-interstitials in hexagonal close packed (hcp) structure, we show that four other configurations, obtained by breaking symmetry of some original ones, may be low-energy local minima or saddle points. The first two, BC${}^{\ensuremath{'}}$ and C${}^{\ensuremath{'}}$, consist basal crowdion buckled perpendicular their axes pyramidal plane, respectively. two others, PS P2S, are rotating $c$-axis split dumbbell prismatic...
Carbon atoms are always present in Fe-based materials, either as impurities even high purity samples or an intrinsic constituent steels. Density Functional Theory calculations have been performed to study the interaction between C and vacancies (V) α-Fe. We find that formation of VCn complexes is energetically favourable for n ≤ 3, with VC2 being most stable one. The energy gain corresponding clustering reaction VCn-1 + → depends mainly on strength C-C covalent bonds. vacancy diffusivity...
This study examined the moderating effects of 3 risk factors-perfectionistic personal discrepancy, perfectionistic family and discrimination-on associations between interpersonal factors (i.e., perceived burdensomeness thwarted belongingness) suicide ideation in a sample 466 Asian international students studying United States. We focused specifically on discrimination maladaptive perfectionism as to Joiner's (2005) theory suicidal behavior. incorporated both discrepancy indicators...
This work is motivated by the need for large-scale simulations to extract physical information on iron-chromium system that a binary model alloy ferritic steels used or proposed in many nuclear applications. From first-principles calculations and experimental critical temperature we build new energetic rigid lattice based pair interactions with concentration dependence. Density functional theory both norm-conserving projector augmented-wave approaches have been performed. A thorough...
Combined density functional theory and empirical-potential calculations are performed to investigate the lowest-energy sites migration mechanisms of He in various $\ensuremath{\alpha}$-Fe grain boundaries (GBs). Before defect calculations, we show that structural optimizations, including simulated annealing atom removal, crucial for locating stable GB structure a given temperature regime. Then, formation energies all substitutional interstitial two different GBs evaluated, showing strong...
The structural arrangements and magnetic properties of iron encapsulated in single wall carbon nanotubes (SWCNT) are investigated. Fe nanowires interest because their potential use spintronics. They have also been fabricated inside nanotubes, where occasionally exchange bias has detected. An additional motivation to study these systems is contribute the understanding how iron-carbon interaction determines ordering. Here we investigate, using ab initio methods, geometry structure freestanding...
The vacancy properties in group-IV hexagonal close-packed metals (Ti, Zr and Hf) have been investigated by Density Functional Theory (DFT) calculations performed with the SIESTA code. migration energies are found to be systematically lower »0.15 eV within basal plane than out of plane. electronic origin this significant contribution diffusion anisotropy is evidenced analysis local densities states a comparison empirical potential. average value migra- tion energy very good agreement...