The lattice contraction of UO2 from Cr doping as determined via high resolution synchrotron X-ray powder diffraction

Murphy, Gabriel L.; Svitlyk, Volodymyr; Henkes, Maximilian; Shirokiy, Daniil; Hennig, Christoph; Kegler, Philip; Bosbach, Dirk; Bukaemskiy, Andrey

doi:10.1016/j.jnucmat.2024.155046

Cited by 2 publications

References 26 publications

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The role of redox and structure on grain growth in Mn-doped UO2

Murphy,

Bazarkina,

Rossberg

et al. 2024

Commun Mater

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Mn-doped UO2 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 UO2 single crystal grains and ceramic specimens. Measurements reveal Mn enters the UO2 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+2O in the bulk material. Extended X-ray absorption near edge structure measurements unveil that during sintering, the isostructural relationship between fluorite UO2 and Mn+2O results in inadvertent interaction and subsequent incorporation of diffusing U species within MnO, rather than neighbouring UO2 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.

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The role of redox and structure on grain growth in Mn-doped UO2

Murphy,

Bazarkina,

Rossberg

et al. 2024

Commun Mater

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Elucidating the Roles of Redox and Structure in the Grain Growth of Mn-doped UO2

Murphy,

Bazarkina,

Rossberg

et al. 2024

Preprint

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Mn-doped UO2 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 growth mechanisms, apparently arising from misunderstandings of its redox-structural chemistry. To resolve this disparity, this investigation has used a combination of synchrotron X-ray diffraction and spectroscopy measurements supported by ab initio calculations to cross-examine the redox and structure chemistry of Mn-doped UO2 single crystal grains and ceramic specimens. Mn was found to enter the UO2 matrix divalently with additional formation of fluorite Mn+ 2O in the bulk material. Extended X-ray absorption near edge structure measurements indicated that due to the isostructural fluorite relationship between UO2 and Mn+ 2O, grain enhancing diffusing U species, that should migrate to neighbour UO2 grains during sintering, are inadvertently incorporating within MnO, inhibiting grain growth. The investigation consequently highlights the significance of considering total redox and structural chemistry of main and minor phases in the design of advanced materials.

show abstract

The lattice contraction of UO2 from Cr doping as determined via high resolution synchrotron X-ray powder diffraction

Cited by 2 publications

References 26 publications

The role of redox and structure on grain growth in Mn-doped UO2

The role of redox and structure on grain growth in Mn-doped UO2

Elucidating the Roles of Redox and Structure in the Grain Growth of Mn-doped UO2

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