Year: 2024
Type: article
Abstract: Mn-doped UO 2 is considered a potential advanced nuclear fuel due to ameliorated microstructural grain growth compared to non-doped variants. However, recent experimental investigations have highlighted limitations in grain growth apparently arising from misunderstandings of its redox-structural chemistry. To resolve this, we use synchrotron X-ray diffraction and spectroscopy measurements supported by ab initio calculations to cross-examine the redox and structural chemistry of Mn-doped UO 2 single crystal grains and ceramic specimens. Measurements reveal Mn enters the UO 2 matrix divalently as $$({{{Mn}}}_{x}^{+2}{{U}}_{1-x}^{+4}){{O}_{2-x}}$$ ( M n x + 2 U 1 − x + 4 ) O 2 − x with the additional formation of fluorite Mn +2 O in the bulk material. Extended X-ray absorption near edge structure measurements unveil that during sintering, the isostructural relationship between fluorite UO 2 and Mn +2 O results in inadvertent interaction and subsequent incorporation of diffusing U species within MnO, rather than neighbouring UO 2 grains, inhibiting grain growth. The investigation consequently highlights the significance of considering total redox-structural chemistry of main and minor phases in advanced ceramic material design.
Source: Communications Materials
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,490
Award: G1373156744
OpenAlex ID: W4405613613