A5013321557- Radioactive element chemistry and processing
- Nuclear materials and radiation effects
- Nuclear Materials and Properties
- Chemical Synthesis and Characterization
- Radioactive contamination and transfer
- Luminescence Properties of Advanced Materials
- Crystal Structures and Properties
- Advanced Condensed Matter Physics
- Inorganic Chemistry and Materials
- Crystallization and Solubility Studies
- Radioactivity and Radon Measurements
- X-ray Diffraction in Crystallography
- Microwave Dielectric Ceramics Synthesis
- Thermal Expansion and Ionic Conductivity
- Nuclear reactor physics and engineering
- Zeolite Catalysis and Synthesis
- Catalytic Processes in Materials Science
- Geochemistry and Elemental Analysis
- Rare-earth and actinide compounds
- Ferroelectric and Piezoelectric Materials
- Nuclear and radioactivity studies
- Glass properties and applications
- Cassava research and cyanide
- Thermodynamic and Structural Properties of Metals and Alloys
- Magnetic and transport properties of perovskites and related materials
Joint Research Centre
2016-2025
Karlsruhe University of Education
2019-2021
European Commission
2017-2019
Alexandru Ioan Cuza University
2007-2016
Université Paris-Est Créteil
2009-2011
Chimie de la Matière Condensée de Paris
2009-2011
Centre National de la Recherche Scientifique
2009-2011
National Research Council Canada
2011
Stony Brook University
2011
Universidade Federal de Uberlândia
2011
Intrinsic properties of a compound (e.g., electronic structure, crystallographic optical and magnetic properties) define notably its chemical physical behavior. In the case nanomaterials, these fundamental depend on occurrence quantum mechanical size effects considerable increase surface to bulk ratio. Here, we explore dependence both crystal CeO2 nanoparticles (NPs) with different sizes by state-of-the art spectroscopic techniques. X-ray diffraction, photoelectron spectroscopy, high-energy...
Abstract Here we provide evidence that the formation of PuO 2 nanoparticles from oxidized Pu VI under alkaline conditions proceeds through an intermediate V solid phase, similar to NH 4 CO 3 , which is stable over a period several months. For first time, state‐of‐the‐art experiments at M and L absorption edges combined with theoretical calculations unambiguously allow determine oxidation state local structure this phase.
Actinide oxalate decomposition under hot compressed water is proposed as a milder production route for nanometric sized (mixed) actinide oxides.
Abstract The hydrothermal decomposition of actinide(IV) oxalates ( An = Th, U, Pu) at temperatures between 95 and 250 °C is shown to lead the production highly crystalline, reactive actinide oxide nanocrystals (NCs). This aqueous process proved be quantitative, reproducible fast (depending on temperature). NCs obtained were characterised by X-ray diffraction TEM showing their size smaller than 15 nm. Attempts extend this general approach towards transition metal or lanthanide failed in...
The actinides possess a complex electronic structure, making their chemical and physical properties among the least understood in periodic table. Advanced spectroscopic tools, able to obtain deep insights into structure binding of actinides, are highly desirable. Here, we introduce two sensitive tools: one determines number localized 5f electrons on an actinide atom, another assesses covalent character actinide-ligand bonding. Both tools based multiplet present M4 edge core-to-core resonant...
ETS-10 titanosilicate was tested as an adsorbent for the removal of Cs+ and Sr2+ cations from radioactive waters, considering both ion exchange behaviour loaded during thermal conditioning. The studies indicate that has a high similar affinity reaching capacity at concentration about 50 milliequivalents gram per liter. Thermal treatment Cs+- Sr2+-exchanged materials results in melting approximately 700 °C. temperature increases with initial is higher than exchanged ETS-10. Recrystallisation...
Nuclear fuels production, structural materials, separation techniques, and waste management, all may benefit from an extensive knowledge in the nano-nuclear technology. In this line, we present here production of U1-xThxO2 (x = 0 to 1) mixed oxides nanocrystals (NC's) through hydrothermal decomposition oxalates hot compressed water at 250 °C. Particles spherical shape size about 5.5–6 nm are obtained during process. The powdery nanocrystalline products were consolidated by spark plasma...
The electronic structure of U(V) - and U(VI) -containing uranates NaUO3 Pb3 UO6 was studied by using an advanced technique, namely X-ray absorption spectroscopy (XAS) in high-energy-resolution fluorescence-detection (HERFD) mode. Due to a significant reduction core-hole lifetime broadening, the crystal-field splittings 5f shell were probed directly HERFD-XAS spectra collected at U 3d edge, which is not possible conventional XAS. In addition, charge-transfer satellites that result from 5f-O...
The non-linear variation of the lattice parameter in U<sup>IV</sup>O<sub>2</sub>–Bi<sub>2</sub>O<sub>3</sub> system under inert atmosphere is due to uranium oxidation.
The AnP2O7 diphosphates (An = Th, U, Np, Pu) have been synthesized by various routes depending on the stability of AnIV cation and its suitability for unusual octahedral environment. Synchrotron X-ray diffraction, thermal analysis, Raman spectroscopy, 31P nuclear magnetic resonance reveal them as a new family which probably includes recently studied CeP2O7. Although they adopt at high temperature same cubic archetypal cell other known MP2O7 diphosphates, differ very faint triclinic...
In order to fulfil the requirements as an actinide waste form, cheralite (CaTh(PO4)2) needs be stabilised into a dense material. Thermal stability studies indicated that heat treatment causes gradual decomposition of CaTh(PO4)2 corresponding oxides above 1550 K. Thus, conventional sintering this material cannot applied. However, we demonstrate rapid densification without can achieved by using spark plasma sintering. High density pellets pure were produced and thermal diffusivity mechanical...
A solid state method was used to synthesize La1-xPuxPO4 (x = 0.01, 0.05, 0.10, 0.15, (0.5)) solutions with monazite structure. XRD measurements of the compounds x 0.50 revealed formation two phases: (La,Pu)PO4-monazite and a cubic phase (PuO2). Pure-phase La1-xPuxPO4-monazite were obtained for materials 0.00–0.15 confirmed by linear dependence lattice parameters on composition according Vegard's law. X-ray absorption spectroscopy (XAS) analysis at Pu-LIII La-LIII edges +III valence plutonium...
We report here a detailed experimental and theoretical investigation of hexavalent uranium in various local configurations with high-energy-resolution fluorescence-detected X-ray absorption near-edge structure at the U M4 edge. show pronounced sensitivity technique to arrangement atoms around absorber provide interpretation revealing nature spectral features. Calculations based on density functional theory crystal field multiplet indicate that for all analyzed, main peak corresponds...