Structural Properties and Charge Distribution of the Sodium Uranium, Neptunium, and Plutonium Ternary Oxides

Structural Properties and Charge Distribution of the Sodium Uranium, Neptunium, and Plutonium Ternary Oxides: A Combined X-ray Diffraction and XANES Study

Smith, A.L. (TU Delft RST/Reactor Physics and Nuclear Materials; European Commission; University of Cambridge)
Martin, Philippe M. (CEA Cadarache)
Prieur, Damien (European Commission)
Scheinost, Andreas C. (Helmholtz Zentrum Dresden Rossendorf)
Raison, Philippe E. (European Commission)
Cheetham, Anthony K. (University of Cambridge)
Konings, R. (TU Delft RST/Reactor Physics and Nuclear Materials; European Commission)

2016

The charge distributions in α-Na₂UO₄, Na₃NpO₄, α-Na₂NpO₄, Na₄NpO₅, Na₅NpO₆, Na₂PuO₃, Na₄PuO₅, and Na₅PuO₆ are investigated in this work using X-ray absorption near-edge structure (XANES) spectroscopy at the U-L₃, Np-L₃, and Pu-L₃ edges. In addition, a Rietveld refinement of monoclinic Na₂PuO₃, in space group C2/c, is reported for the first time, and the existence of the isostructural Na₂NpO₃ phase is revealed. In contrast to measurements in solution, the number of published XANES data for neptunium and plutonium solid phases with a valence state higher than IV is very limited. The present results cover a wide range of oxidation states, namely, IV to VII, and can serve as reference for future investigations. The sodium actinide series show a variety of local coordination geometries, and correlations between the shape of the XANES spectra and the local structural environments are discussed herein.

http://resolver.tudelft.nl/uuid:910006d8-c39d-42cb-ac60-1bb784b29ac9

https://doi.org/10.1021/acs.inorgchem.5b02476

0020-1669

Inorganic Chemistry, 55 (4), 1569-1579

Institutional Repository

journal article

© 2016 A.L. Smith, Philippe M. Martin, Damien Prieur, Andreas C. Scheinost, Philippe E. Raison, Anthony K. Cheetham, R. Konings