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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Dacheux, Nicolas
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (17/17 displayed)
- 2024Speciation and chemical behavior of molybdenum in uranium dioxide samples prepared by hydroxide precipitationcitations
- 2024Speciation and chemical behavior of molybdenum in uranium dioxide samples prepared by hydroxide precipitationcitations
- 2023Synthesis and sintering of homogenous Hf1-xMIIIxO2-x/2 ceramics as solid electrolytes for oxygen sensors in liquid sodium
- 2023Understanding the solid/liquid interface evolution during the dissolution of Nd-doped UO2 by macro-/microscopic dual approachcitations
- 2022Synchrotron study of the relations between sintering conditions, structure and cation speciation in (U,Ce)O2+δ ceramics
- 2022Synthesis and sintering of homogenous Hf1-xMIIIxO2-x/2 ceramics as solid electrolytes for oxygen sensors operating in liquid sodium
- 2022Experimental approach to study the alteration of MOX MIMAS fuels in an underwater storage situation
- 2022Characterization and dissolution of (Ru, Rh, Pd, Mo)-bearing (U,Th)O2 heterogeneous mixed oxides for spent fuel modeling
- 2022Impact of impurities on the fabrication and performances of yttrium-doped thoria electrolyte ceramicscitations
- 2021The Role of Water and Hydroxyl Groups in the Structures of Stetindite and Coffinite, MSiO4 (M = Ce, U).citations
- 2020An in-situ electron microscopy study of dual ion-beam irradiated xenotime-type ErPO$_4$citations
- 2019Deciphering the Crystal Structure of a Scarce 1D Polymeric Thorium Peroxo Sulfate
- 2019Impact of the cationic homogeneity on Th0.5U0.5O2 densification and chemical durabilitycitations
- 2019Impact of the cationic homogeneity on Th$_{0.5}$U$_{0.5}$O$_2$ densification and chemical durabilitycitations
- 2017Synthesis and Direct Sintering of Nanosized (M IV ,M III )O 2‐ x Hydrated Oxides as Electrolyte Ceramicscitations
- 2017Study of the hydrothermal synthesis of ThSiO4, USiO4 and CeSiO4 aiming at determining the conditions of PuSiO4 formation
- 2017Novel approaches for the in situ study of the sintering of nuclear oxide fuel materials and their surrogatescitations
Places of action
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article
The Role of Water and Hydroxyl Groups in the Structures of Stetindite and Coffinite, MSiO4 (M = Ce, U).
Abstract
Orthosilicates adopt the zircon structure types (I41/amd), consisting of isolated SiO4 tetrahedra joined by A-site metal cations, such as Ce and U. They are of significant interest in the fields of geochemistry, mineralogy, nuclear waste form development, and material science. Stetindite (CeSiO4) and coffinite (USiO4) can be formed under hydrothermal conditions despite both being thermodynamically metastable. Water has been hypothesized to play a significant role in stabilizing and forming these orthosilicate phases, though little experimental evidence exists. To understand the effects of hydration or hydroxylation on these orthosilicates, in situ high-temperature synchrotron and laboratory-based X-ray diffraction was conducted from 25 to ∼850 °C. Stetindite maintains its I41/amd symmetry with increasing temperature but exhibits a discontinuous expansion along the a-axis during heating, presumably due to the removal of water confined in the [001] channels, which shrink against thermal expansion along the a-axis. Additional in situ high-temperature Raman and Fourier transform infrared spectroscopy also confirmed the presence of the confined water. Coffinite was also found to expand nonlinearly up to 600 °C and then thermally decompose into a mixture of UO2 and SiO2. A combination of dehydration and dehydroxylation is proposed for explaining the thermal behavior of coffinite synthesized hydrothermally. Additionally, we investigated high-temperature structures of two coffinite-thorite solid solutions, uranothorite (UxTh1-xSiO4), which displayed complex variations in composition during heating that was attributed to the negative enthalpy of mixing. Lastly, for the first time, the coefficients of thermal expansion of CeSiO4, USiO4, U0.46Th0.54SiO4, and U0.9Th0.1SiO4 were determined to be αV = 14.49 × 10-6, 14.29 × 10-6, 17.21 × 10-6, and 17.23 × 10-6 °C-1, respectively.