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

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• 作者：Anna L. Smith ; Philippe Martin ; Damien Prieur ; Andreas C. Scheinost ; Philippe E. Raison ; Anthony K. Cheetham ; Rudy J. M. Konings
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：February 15, 2016
• 年：2016
• 卷：55
• 期：4
• 页码：1569-1579
• 全文大小：550K
• ISSN：1520-510X

文摘

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.