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arXiv · 2010.08231

The application of HEXS and HERFD XANES for accurate structural characterization of actinide nanomaterials: application to ThO2

Lucia Amidani·Gavin B. M. Vaughan·Tatiana V. Plakhova·Anna Yu. Romanchuk·Evgeny Gerber·Roman Svetogorov·Stephan Weiss·Yves Joly·Stephan N. Kalmykov·Kristina O. Kvashnina
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Abstract

Structural characterization of actinide nanoparticles (NPs) is of primary importance and hard to achieve, especially for non-homogeneous samples with NPs below 3 nm. By combining High Energy X-ray Scattering (HEXS) and High-Energy-Resolution Fluorescence Detected X-ray Near-Edge Structure (HERFD XANES), we characterized for the first time both short- and medium-range order of ThO2 NPs obtained by chemical precipitation. With this methodology, a novel insight into the structure of NPs at different steps of their formation process is achieved. The Pair Distribution Function (PDF) reveals a high concentration of ThO2 small units similar to Th hexamer clusters mixed with 1 nm ThO2 NPs in the initial steps of formation. Drying the precipitates at 150 C promotes recrystallization of the smallest units into more thermodynamically stable ThO2 NPs. HERFD XANES at Th M4 edge, a direct probe of the f states, shows variations that we correlate to the break of the local symmetry around Th atoms, which most likely concerns surface atoms. Together, HEXS and HERFD are a powerful methodology to investigate actinide NPs and their formation mechanism.

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Lucia Amidani, Gavin B. M. Vaughan, Tatiana V. Plakhova, Anna Yu. Romanchuk, Evgeny Gerber, Roman Svetogorov, Stephan Weiss, Yves Joly, Stephan N. Kalmykov, Kristina O. Kvashnina. 2020-10-16. The application of HEXS and HERFD XANES for accurate structural characterization of actinide nanomaterials: application to ThO2. https://doi.org/10.1002/chem.202003360

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