X-ray Diffraction, Mössbauer Spectroscopy, Magnetic Susceptibility, and Specific Heat Investigations of Na4NpO5 and Na5NpO6
| Autor: | Anthony K. Cheetham, Nicola Magnani, Roberto Caciuffo, Rudy J. M. Konings, Philippe E. Raison, Jean-Christophe Griveau, Amir Hen, Anna Smith, J. P. Sanchez, Eric Colineau |
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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), Magnétisme et Diffusion Neutronique (MDN), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]) |
| Rok vydání: | 2015 |
| Předmět: |
Lithium Und Natrium
[PHYS]Physics [physics] Crystal-Structure Na4UO5 Valence (chemistry) Np-237 Chemistry 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Magnetic susceptibility 0104 chemical sciences Inorganic Chemistry Tetragonal crystal system Crystallography Quadrupole Mössbauer spectroscopy X-ray crystallography Physical and Theoretical Chemistry 0210 nano-technology Powder Diffraction Powder diffraction Capacity Measurements Monoclinic crystal system |
| Zdroj: | Inorganic Chemistry Inorganic Chemistry, 2015, 54, pp.4556-4564. ⟨10.1021/acs.inorgchem.5b00462⟩ Inorganic Chemistry, American Chemical Society, 2015, 54, pp.4556-4564. ⟨10.1021/acs.inorgchem.5b00462⟩ |
| ISSN: | 1520-510X 0020-1669 |
| DOI: | 10.1021/acs.inorgchem.5b00462 |
| Popis: | International audience; The hexavalent and heptavalent sodium neptunate compounds Na$_4$NpO$_5$ and Na$_5$NpO$_6$ have been investigated using X-ray powder diffraction, Mossbauer spectroscopy, magnetic susceptibility, and specific heat measurements. Na$_4$NpO$_5$ has tetragonal symmetry in the space group 14/m, while Na$_5$NpO$_6$ adopts a monoclinic unit cell in the space group C2/m. Both structures have been refined for the first time using the Rietveld method. The valence states of neptunium in these two compounds, i.e., Np(VI) and Np(VII), respectively, have been confirmed by the isomer shift values of their Mossbauer spectra. The local structural properties obtained from the X-ray refinements have also been related to the quadrupole coupling constants and asymmetry parameters determined from the Mossbauer studies. The absence of magnetic ordering has been confirmed for Na$_4$NpO$_5$. However, specific heat measurements at low temperatures have suggested the existence of a Schottky-type anomaly at around 7 K in this Np(VI) phase. |
| Databáze: | OpenAIRE |
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