Moreau LM, Herve A, Straub MD, Russo DR, Abergel RJ, Alayoglu S, Arnold J, Braun A, Deblonde GJP, Liu Y, Lohrey TD, Olive DT, Qiao Y, Rees JA, Shuh DK, Teat SJ, Booth CH, Minasian SG. Structural properties of ultra-small thorium and uranium dioxide nanoparticles embedded in a covalent organic framework.
Chem Sci 2020;
11:4648-4668. [PMID:
34122920 PMCID:
PMC8159168 DOI:
10.1039/c9sc06117g]
[Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 04/13/2020] [Indexed: 01/23/2023] Open
Abstract
We report the structural properties of ultra-small ThO2 and UO2 nanoparticles (NPs), which were synthesized without strong binding surface ligands by employing a covalent organic framework (COF-5) as an inert template. The resultant NPs were used to observe how structural properties are affected by decreasing grain size within bulk actinide oxides, which has implications for understanding the behavior of nuclear fuel materials. Through a comprehensive characterization strategy, we gain insight regarding how structure at the NP surface differs from the interior. Characterization using electron microscopy and small-angle X-ray scattering indicates that growth of the ThO2 and UO2 NPs was confined by the pores of the COF template, resulting in sub-3 nm particles. X-ray absorption fine structure spectroscopy results indicate that the NPs are best described as ThO2 and UO2 materials with unpassivated surfaces. The surface layers of these particles compensate for high surface energy by exhibiting a broader distribution of Th-O and U-O bond distances despite retaining average bond lengths that are characteristic of bulk ThO2 and UO2. The combined synthesis and physical characterization efforts provide a detailed picture of actinide oxide structure at the nanoscale, which remains highly underexplored compared to transition metal counterparts.
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