A Na-23 Magic Angle Spinning Nuclear Magnetic Resonance, XANES, and High-Temperature X-ray Diffraction Study of NaUO3, Na4UO5, and Na2U2O7
| Autor: | Philippe E. Raison, R.J.M. Konings, Laura Martel, Ian Farnan, Anthony K. Cheetham, Andreas C. Scheinost, Christoph Hennig, Thibault Charpentier, Damien Prieur, Anna Smith |
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| Přispěvatelé: | JRC Institute for Transuranium Elements [Karlsruhe] (ITU ), European Commission - Joint Research Centre [Karlsruhe] (JRC), Department of Materials Science and Metallurgy [Cambridge University] (DMSM), University of Cambridge [UK] (CAM), Laboratoire Structure et Dynamique par Résonance Magnétique (LCF) (LSDRM), Nanosciences et Innovation pour les Matériaux, la Biomédecine et l'Energie (ex SIS2M) (NIMBE UMR 3685), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Department of Earth Sciences [Cambridge, UK], Institute of Resource Ecology [Dresden] (IRE), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC) |
| Jazyk: | angličtina |
| Rok vydání: | 2014 |
| Předmět: |
Valence (chemistry)
Chemistry Chemical shift nmr chemical-shifts solid-state nmr local-structure silicate crystals mas nmr u-o spectra na glasses system 02 engineering and technology Electronic structure 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences XANES 0104 chemical sciences Inorganic Chemistry Paramagnetism Crystallography Nuclear magnetic resonance X-ray crystallography Magic angle spinning [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph] Physical and Theoretical Chemistry 0210 nano-technology Spectroscopy |
| Zdroj: | Inorganic Chemistry Inorganic Chemistry, 2014, 53 (1), pp.375-382. ⟨10.1021/ic402306c⟩ Inorganic Chemistry, American Chemical Society, 2014, 53 (1), pp.375-382. ⟨10.1021/ic402306c⟩ |
| ISSN: | 0020-1669 1520-510X |
| DOI: | 10.1021/ic402306c⟩ |
| Popis: | International audience; The valence state of uranium has been confirmed for the three sodium uranates (NaUO3)-O-V/[Rn](5f(1)), (Na4UO5)-O-VI/[Rn](5f(0)), and (Na2U2O7)-O-VI/[Rn] (5f(0)), using X-ray absorption near-edge structure (XANES) spectroscopy. Solid-state Na-23 magic angle spinning nuclear magnetic resonance (MAS NMR) measurements have been performed for the first time, yielding chemical shifts at -29.1 (NaUO3), 15.1 (Na4UO5), and -14.1 and -19 ppm (Na1 8-fold coordinated and Na2 7-fold coordinated in Na2U2O7), respectively. The [Rn]5f(1) electronic structure of uranium in NaUO3 causes a paramagnetic shift in comparison to Na4UO5 and Na2U2O7, where the electronic structure is [Rn] 5f(0). A Na-23 multi quantum magic angle spinning (MQMAS) study on Na2U2O7 has confirmed a monoclinic rather than rhombohedral structure with evidence for two distinct Na sites. DFT calculations of the NMR parameters on the nonmagnetic compounds Na4UO5 and Na2U2O7 have permitted the differentiation between the two Na sites of the Na2U2O7 structure. The linear thermal expansion coefficients of all three compounds have been determined using high-temperature X-ray diffraction: alpha(a) = 22.7 X 10(-6) K-1, alpha(b) = 12.9 X 10(-6) K-1, alpha(c) = 16.2 x 10(-6) K-1, and alpha(vol) = 52.8 X 10(-6) K-1 for NaUO3 in the range 298-1273 K; alpha(a) = 37.1 X 10(-6) K-1, alpha(c) = 6.2 X 10(-6) K-1, and alpha(vol) = 81.8 X 10(-6) K-1 for Na4UO5 in the range 298-1073 K; alpha(a) = 6.7 x 10(-6) K-1, alpha(b) = 14.4 X 10(-6) K-1, alpha(c) = 26.8 X 10(-6) K-1, alpha(beta) = -7.8 X 10(-6) K-1 and alpha(vol) = -217.6 x 10(-6) K-1 for Na2U2O7 in the range 298-573 K. The alpha to beta phase transition reported for the last compound above about 600 K was not observed in the present studies, either by high-temperature X-ray diffraction or by differential scanning calorimetry. |
| Databáze: | OpenAIRE |
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