The application of HEXS and HERFD XANES for accurate structural characterization of actinide nanomaterials: application to ThO₂.
The application of HEXS and HERFD XANES for accurate structural characterization of actinide nanomaterials: application to ThO₂.
Amidani, L.; Vaughan, G. B. M.; Plakhova, T. V.; Romanchuk, A. Y.; Gerber, E.; Svetogorov, R.; Weiß, S.; Joly, Y.; Kalmykov, S. N.; Kvashnina, K.
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.
Keywords: actinides; HERFD; HEXS; nanoparticles; ThO₂
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Chemistry - A European Journal 27(2021)1, 252-263
Online First (2020) DOI: 10.1002/chem.202003360
Permalink: https://www.hzdr.de/publications/Publ-30838