How are phase-pure actinide oxides synthesized?

Appie Peterson, Stefan Minasian, and their colleagues at the University of California – Berkeley and Berkeley Lab published work using the Hummingbird Scientific tomography TEM sample holder to perform STEM and EDS characterization of fully-stoichiometric and phase-pure neptunium and plutonium dioxides. The oxidation-state pure actinide oxides were synthesized using precursor molecules with amidate-based ligands subjected to mild thermolysis.

a) Schematic of the formation of actinide dioxides from precursor molecules. High-angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) images of b) NpO₂and f) PuO₂ were prepared at 270 °C. Energy dispersive X-ray spectroscopy (EDS) elemental maps of oxygen (c and g) or actinide (Np, d and Pu, h) with the corresponding spectra (Np, e and Pu, i). Au, Ti, Fe, Cu and C are all present in the tomography tip, specimen holder, and TEM grids. Copyright © 2024 The Authors. Published by American Chemical Society. This publication is licensed under CC-BY-NC-ND 4.0.

The precursors were characterized by NMR spectroscopy and single crystal X-ray diffraction, while synthesized oxides were characterized by STEM-EDS and powder X-ray diffraction confirming the formation of stoichiometric NpO₂ and PuO₂. The Hummingbird Scientific tomography sample holder optimizes spectroscopic signal collection with its ultra-high stability over long collection times and low-profile tip which reduces unwanted signal from the holder. The results support previous work indicating that the stoichiometric control is due to the preformed metal–oxygen bond in the precursor, while the oxidation state is predetermined by the precursor coordination complex. The high-purity synthetic samples can be synthesized under mild, inert conditions and are suitable for a range of characterization techniques aiding nuclear forensics, nonproliferation, and spent fuel degradation.

Reference: Appie Peterson, Sheridon N. Kelly, Trevor Arino, S. Olivia Gunther, Erik T. Ouellette, Jennifer N. Wacker, Joshua J. Woods, Simon J. Teat, Wayne W. Lukens, John Arnold, Rebecca J. Abergel, Stefan G. Minasian, Inorganic Chemistry XXXX (XXX) XXX–XXX (2024) DOI: 10.1021/acs.inorgchem.4c02099

Full paper Copyright © 2024 The Authors. Published by American Chemical Society. This publication is licensed under  CC-BY-NC-ND 4.0.

 

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