Assessing UO2 sample quality with μ-Raman spectroscopy

Rickert, Karl; Prusnick, Timothy; Kimani, Martin M.; Moore, Elizabeth A.; Merriman, C.A.; Mann, J. Matthew

doi:10.1016/j.jnucmat.2018.11.009

Cited by 20 publications

(30 citation statements)

References 39 publications

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“…Although the 2LO band did not provide useful maps in the annealed UO 2 sample, the sensitivity of the 2LO band to oxidation could prove beneficial for measuring small differences between grains in in situ oxidation experiments. [ 27 ]…”

Section: Mapping Uo2mentioning

confidence: 99%

Benefits of using multiple Raman laser wavelengths for characterizing defects in a UO₂ matrix

Karcher

Mohun

Olds

et al. 2022

J Raman Spectroscopy

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Raman spectroscopy is one of the most useful techniques for studying the structure of UO 2 and changes due to specific defects caused by doping, changes in stoichiometry, irradiation, or heating under oxidizing conditions. In this paper, we illustrate several aspects of the application of Raman techniques to the study of UO 2 , including the use of wavelength-dependent excitation (455, 532, and 785 nm) to assess the effects of doping (Nd, Th, and Zr), ion irradiation, and in situ heating and oxidation (UO 2 to U 3 O 8 ). Additionally, we show examples of how correlative microscopy is possible using electron backscatter diffraction combined with Raman maps of specific vibration bands or of laser-induced luminescence generated by rare-earth dopants in the matrix.For each of these applications, we suggest optimal excitation wavelengths that vary depending on the desired data. Blue (455 nm) excitation tends to promote oxidation even at low powers, but because Raman spectra change little with doping, irradiation-induced changes are easier to observe. Green (532 nm) excitation is optimal for observing electron-phonon resonance effects in UO 2 and offers a good compromise for high-temperature oxidation experiments, delivering high-quality spectra for both UO 2 and U 3 O 8 . Infrared (785 nm) excitation is best for observing "defect" bands associated with doping in UO 2 , as changes with irradiation are small. Raman spectroscopy is particularly suited for studying the stability of UO 2 towards oxidation in the presence of dopants simulating fission products, where electron-phonon resonant effects, dopant ion luminescence, and mapping can be used together to investigate structural rearrangement as a function of temperature. These techniques can offer insight into microstructural changes in UO 2 fuels at higher burnups envisioned in future reactors.

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Section: Mapping Uo2mentioning

confidence: 99%

Benefits of using multiple Raman laser wavelengths for characterizing defects in a UO₂ matrix

Karcher

Mohun

Olds

et al. 2022

J Raman Spectroscopy

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“…If the melt growth is eschewed because of these assorted shortcomings, the next most common growth techniques dissolve the feedstock under conditions well below the melting point and then crystallize out the feedstock from the solution. Chemical vapor deposition (CVD) or chemical transport (UO2 [228,229,230,231], UxTh1-xO2 [232], and U1-xPuxO2 [233]), flux (CeO2 [234,235,236,237,238,239,240,241], ThO2 [220,223,234,235,236,237,238,242,243,244,245,246,247], UO2 [217,248,249], UxTh1-xO2 [249], and PuO2 [242,250,251,252,253]), and hydrothermal or solvothermal synthesis (CeO2 [254], ThO2 [29,67,179,255,256,257,258,259,260,…”

Section: Bulk Crystal Growth Techniquesmentioning

confidence: 99%

“…Raman spectroscopy allows probing of vibrational properties of fluorite crystals [365,366,367] and can be used to characterize point defects and small defect clusters. Raman spectra of UO2 has been presented in a number of studies [258,368], while reports on ThO2 are more limited [29,321]. An extensive body of literature exists for CeO2 and ZrO2 [369,370].…”

Section: Raman Spectroscopymentioning

confidence: 99%

Thermal Energy Transport in Oxide Nuclear Fuel

et al. 2021

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To efficiently capture the energy of the nuclear bond, advanced nuclear reactor concepts seek solid fuels that must withstand unprecedented temperature and radiation extremes. In these advanced fuels, thermal energy transport under irradiation is directly related to reactor performance as well as reactor safety. The science of thermal transport in nuclear fuel is a grand challenge due to both computational and experimental complexities. Here, we provide a comprehensive review of thermal transport research on two actinide oxides: one currently in use in commercial nuclear reactors, uranium dioxide (UO2), and one advanced fuel candidate material, thorium dioxide (ThO2). In both materials, 5Concluding Remarks .

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“…Urania and thoria have gained substantial attention for their use in nuclear fuels, weapons, and their semiconductor properties. [ 16–19 ] However, the existing literature on polarized Raman characterization of urania crystallographic orientation does not take grain orientation into full account and is primarily based on polycrystalline or undefined single crystals. [ 5,20,21 ] Urania and other actinide dioxides belong to the space group Fm

\overset{3}{true}

m (O 5 h ), which has only one Raman active phonon.…”

Section: Introductionmentioning

confidence: 99%

Identifying crystallographic faces of the fluorites urania and thoria with rotational polarized Raman spectroscopy

Morgan

Prusnick

Velez

et al. 2021

J Raman Spectroscopy

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Crystallite orientation identification is invaluable, but is often limited to small area identification or requires a large area sample. Nondestructive optical methods such as polarized Raman spectroscopy, in contrast, can be used to completely map a variety of sample sizes, but their potential is not yet fully realized. Here, we report a systematic study of polarized Raman scattering of high-quality, hydrothermally grown, single crystals of urania and thoria. The peak intensity variations for as-grown major crystal planes, post-growth polished crystal planes, and a post-growth polished non-crystallographic plane are directly linked to crystallographic orientation and crystal rotation, and agree with computed models. In particular, the parallel polarized peak intensity results are directly correlated with metal-oxygen-metal chains in the fluorite structure and can be used to determine both orientation and rotational alignment of a given crystal face if sufficiently small rotational steps are applied. These results are structure based, being applicable to the larger fluorite phase space, which is useful for optical, semiconductor, nuclear, and solid oxide fuel cell industries. Further, these results suggest that Raman spectroscopy can identify non-crystallographic orientations that are not discernable by traditional means.

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Assessing UO2 sample quality with μ-Raman spectroscopy

Cited by 20 publications

References 39 publications

Benefits of using multiple Raman laser wavelengths for characterizing defects in a UO₂ matrix

Benefits of using multiple Raman laser wavelengths for characterizing defects in a UO₂ matrix

Thermal Energy Transport in Oxide Nuclear Fuel

Identifying crystallographic faces of the fluorites urania and thoria with rotational polarized Raman spectroscopy

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Assessing UO2 sample quality with μ-Raman spectroscopy

Cited by 20 publications

References 39 publications

Benefits of using multiple Raman laser wavelengths for characterizing defects in a UO2 matrix

Benefits of using multiple Raman laser wavelengths for characterizing defects in a UO2 matrix

Thermal Energy Transport in Oxide Nuclear Fuel

Identifying crystallographic faces of the fluorites urania and thoria with rotational polarized Raman spectroscopy

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Benefits of using multiple Raman laser wavelengths for characterizing defects in a UO₂ matrix

Benefits of using multiple Raman laser wavelengths for characterizing defects in a UO₂ matrix