Review of recent experimental results on the behavior of actinide-bearing oxides and related materials in extreme environments

Tracy, Cameron L.; Lang, Maik; Zhang, F.X.; Park, Sulgiye; Palomares, Raul I.; Ewing, Rodney C.

doi:10.1016/j.pnucene.2016.09.012

Cited by 13 publications

(4 citation statements)

References 138 publications

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“…The structural transitions that result from extreme environments have been of great interest for pyrochlore-type materials [38]. Pyrochlorestructured materials have been proposed for applications such as hosting immobilized actinides from nuclear fuel reprocessing or dismantled nuclear weapons [39,40].…”

Section: Introductionmentioning

confidence: 99%

Pressure-induced structural modifications of rare-earth hafnate pyrochlore

Turner

Rittman

Heymach

et al. 2017

J. Phys.: Condens. Matter

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Complex oxides with the pyrochlore (ABO) and defect-fluorite ((A,B)O) structure-types undergo structural transformations under high-pressure. Rare-earth hafnates (AHfO) form the pyrochlore structure for A = La-Tb and the defect-fluorite structure for A = Dy-Lu. High-pressure transformations in AHfO pyrochlore (A = Sm, Eu, Gd) and defect-fluorite (A = Dy, Y, Yb) were investigated up to ~50 GPa and characterized by in situ Raman spectroscopy and synchrotron x-ray diffraction (XRD). Raman spectra at ambient pressure revealed that all compositions, including the defect-fluorites, have some pyrochlore-type short-range order. In situ high-pressure synchrotron XRD showed that all of the rare earth hafnates investigated undergo a pressure-induced phase transition to a cotunnite-like (orthorhombic) structure that begins between 18 and 25 GPa. The phase transition to the cotunnite-like structure is not complete at 50 GPa, and upon release of pressure, the hafnates transform to defect-fluorite with an amorphous component. For all compositions, in situ Raman spectroscopy showed that disordering occurs gradually with increasing pressure. Pyrochlore-structured hafnates retain their short-range order to a higher pressure (30 GPa vs. <10 GPa) than defect-fluorite-structured hafnates. Rare earth hafnates quenched from 50 GPa show Raman spectra consistent with weberite-type structures, as also reported for irradiated rare-earth stannates. The second-order Birch-Murnaghan equation of state fit gives a bulk modulus of ~250 GPa for hafnates with the pyrochlore structure, and ~400 GPa for hafnates with the defect-fluorite structure. DyHfO is intermediate in its response, with some pyrochlore-type ordering, based on Raman spectroscopy and the equation of state, with a bulk modulus of ~300 GPa. As predicted based on the similar ionic radius of Zr and Hf, rare-earth hafnates show similar behavior to that reported for rare earth zirconates at high pressure.

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Section: Introductionmentioning

confidence: 99%

Pressure-induced structural modifications of rare-earth hafnate pyrochlore

Turner

Rittman

Heymach

et al. 2017

J. Phys.: Condens. Matter

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“…This competition creates large local distortions in the crystal structure. Macroscopically, the lattice swells proportionally to the magnitude of deviation from stoichiometry (Markin and Street, 1967;Vauchy et al, 2014b;Vauchy et al, 2017;Tracy et al, 2018).…”

Section: Interdiffusion In Hypostoichiometry (O/m < 2)mentioning

confidence: 99%

Cation interdiffusion in uranium–plutonium mixed oxide fuels: Where are we now?

Vauchy

Hirooka²,

Matsumoto³

et al. 2022

Front. Nucl. Eng.

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The diffusion phenomena in uranium–plutonium mixed oxides U1−yPuyO2 dictate the physicochemical properties of mixed oxides (MOX) nuclear fuel throughout manufacturing, irradiation, and storage. More precisely, it is paramount to estimate the cation interdiffusion insofar as it dovetails with the actinide redistribution during sintering and under irradiation. This paper draws a critical review of the existing experimental data of U and Pu interdiffusion coefficients in MOX fuel.

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“…However, to the best of our knowledge, there are no reported results on the high-pressure behavior of pre-irradiated CeO 2 with SHI. 48 In this study, the polycrystalline CeO 2 was first irradiated with 5.98 MeV/u 129 Xe ions over a large fluence range of 3×10 10 -2×10 13 ions/cm 2 . Then, the irradiated CeO 2 was compressed in diamond anvil cell (DAC) up to 45 GPa, using argon as the pressure-transmitting medium to avoid any possible reaction with the irradiated CeO 2 and to provide a quasi-hydrostatic condition.…”

Section: Introductionmentioning

confidence: 99%

Phase stability of pre‐irradiated CeO₂ with swift heavy ions under high pressure up to 45 GPa

et al. 2021

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The effect of defects on the high-pressure behavior of materials is fundamental to understanding and designing materials for extreme environments. Previous work has demonstrated that radiation damage can enhance phase stability or alter the transformation pathway. Here, we report the high-pressure phase stability of CeO 2 irradiated by swift heavy ions. CeO 2 is of particular interest because it can be used as a non-radioactive surrogate for UO 2 and PuO 2 . High-pressure Raman spectroscopy shows that low-fluence ion irradiated CeO 2 exhibits nearly the same high-pressure behavior as unirradiated CeO 2 ; whereas, after highfluence irradiation, the phase stability of CeO 2 is significantly enhanced, with the critical phase transition pressure increased from 31.7 to 37.3 GPa and only about 7% high-pressure phase transition fraction at 45.1 GPa. In comparison with the high-pressure Raman results of pre-irradiated CeO 2 before and after 573, 1073, and 1 273 K annealing in air, we propose that large interstitial-type defect clusters, such as dislocation loops formed in heavily-irradiated CeO 2 , are predominately responsible for the increased phase stability at high pressures.

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Review of recent experimental results on the behavior of actinide-bearing oxides and related materials in extreme environments

Cited by 13 publications

References 138 publications

Pressure-induced structural modifications of rare-earth hafnate pyrochlore

Pressure-induced structural modifications of rare-earth hafnate pyrochlore

Cation interdiffusion in uranium–plutonium mixed oxide fuels: Where are we now?

Phase stability of pre‐irradiated CeO₂ with swift heavy ions under high pressure up to 45 GPa

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Review of recent experimental results on the behavior of actinide-bearing oxides and related materials in extreme environments

Cited by 13 publications

References 138 publications

Pressure-induced structural modifications of rare-earth hafnate pyrochlore

Pressure-induced structural modifications of rare-earth hafnate pyrochlore

Cation interdiffusion in uranium–plutonium mixed oxide fuels: Where are we now?

Phase stability of pre‐irradiated CeO2 with swift heavy ions under high pressure up to 45 GPa

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Product

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Phase stability of pre‐irradiated CeO₂ with swift heavy ions under high pressure up to 45 GPa