Absorption spectrum of single-crystal UO2: Identification of and effect of temperature on the peak positions of essentially all optical transitions in the visible to near infrared regions using derivative spectroscopy

Griffiths, Trevor R.; Hubbard, Hugh V.St.A.

doi:10.1016/0022-3115(91)90510-e

Cited by 22 publications

(24 citation statements)

References 14 publications

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“…5. In agreement with the study by Schoenes [22] and Griffiths et al [23,24], we observe at room temperature a strong light absorption occurring for incident light energies higher than 1.9/2 eV: this corresponds to the so-called gap (E g ).…”

Section: Thermal Variation Of the Absorption Edgesupporting

confidence: 88%

“…Recently, in an electrical conductivity study, we have found a gap of E g $ 2 eV which confirms the previous results [13]. This gap energy determined from electrical conductivity is in agreement with the band gap deduced from UV-VIS-NIR optical absorption measurements performed in the range 10-300 K [22][23][24].…”

Section: Introductionsupporting

confidence: 89%

“…In our measurement the black body radiation of our furnace seems to be larger than that of Griffiths et al [24] because, we can clearly distinguish the absorption peaks around 0.5 eV only after making allowance of the black body. Consequently, it appears that the resolution of the fine structure in the range 0.5-1 eV is more difficult in our study.…”

Section: Measurementscontrasting

confidence: 48%

“…Comparison with recent new thermodynamical data of stoichiometric UO 2 [30,41,42]. small shift to the lower energy of the absorption edge was reported from 85-100 K to 300 K (DE g ðT Þ $ 0:05 eV) [22][23][24]. This situation contrasts with that in the range 300-1173 K, where the onset of the optical absorption shifts drastically to lower energies.…”

Section: Thermal Variation Of the Absorption Edgecontrasting

confidence: 45%

“…A red shift of the UO 2 gap was observed by Schoenes [22] from 5 to 300 K and has been attributed to phonon assisted optical transition. The study of Griffiths et al [23,24] has also revealed a large red shift of the absorption edge (gap) from 85 to 985 K. They report a gap decrease of $0.4 eV from 85 to 985 K. Such quite large variation, typical to oxides [32,33], halides [34], and polar semiconductor [35,36], indicates that the electron-lattice interaction is important in UO 2 as expected because we know polaron actually exist.…”

Section: Introductionmentioning

confidence: 91%

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Thermal variation of the optical absorption of UO2: determination of the small polaron self-energy

Ruello

Becker

Ullrich

et al. 2004

Journal of Nuclear Materials

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Section: Thermal Variation Of the Absorption Edgesupporting

confidence: 88%

Section: Introductionsupporting

confidence: 89%

Section: Measurementscontrasting

confidence: 48%

Section: Thermal Variation Of the Absorption Edgecontrasting

confidence: 45%

Section: Introductionmentioning

confidence: 91%

See 3 more Smart Citations

Thermal variation of the optical absorption of UO2: determination of the small polaron self-energy

Ruello

Becker

Ullrich

et al. 2004

Journal of Nuclear Materials

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Raman scattering from phonons and electronic excitations in UO₂with different oxygen isotopes

Gan

Guo

et al. 2015

J. Raman Spectrosc.

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Comparison of the phonons and electronic excitations of UO2 with different oxygen isotopes (16O, 18O), two purely electronic excitations at 4162 and 5778 cm−1 have been evidenced by their limited shift, when 16O is replaced by 18O. The bands observed at 570, 1144 and 2300 cm−1 in U16O2 shift to 545, 1091 and 2190 cm−1 for U18O2. The wavenumbers and the isotope shifts of these bands exhibit multiple relationships. It supports the assignments of the 1LO (~570 cm−1) and 2LO (~1144 cm−1) phonons for U16O2. Both bands exhibit marked decrease for increasing O/U ratio. The observed phenomenon is regarded as a good estimation of the stoichiometry of a uranium oxide. In addition, by analyzing the intensity ratios of the 2LO to 1LO phonons for various UO2 samples, the 2LO band is assigned to the Fröhlich interaction. Defect‐induced and/or deformation potential mechanisms play a dominant role for the 1LO band. Copyright © 2015 John Wiley & Sons, Ltd.

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Isotopic effect of oxygen on the Raman mapping of a polycrystalline uranium dioxide UO₂

Gaillard,

Sarrasin,

Panetier

et al. 2024

J Raman Spectroscopy

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Uranium dioxide (UO2) is a widely studied material due to its use as fuel in pressurised water reactors (PWR), and Raman spectroscopy is a technique of choice to characterise the evolution of its microstructure. UO2 crystallises in a fluorite CaF2 (space group Fm‐3m) structure that gives rise to a unique Raman signature, the T2g band. However, several other bands are often detected whose attribution remains unclear. The present study gives new insights on the Raman spectrum of UO2 thanks to the combination of isotopic labelling with 18O and Raman imaging. In addition to the expected T2g, U2 (LO), 2LO and U3 bands, we have detected a doublet at 885 and 925 cm−1, a U* band at 555 cm−1 in some specific areas and two bands located at 367 and 1196 cm−1. All Raman bands shift under the effect of the replacement of 16O by 18O, excepting for the U* band that could not be detected anymore. The isotopic shift ratio could be determined for 20% and 30% 18O labelling. No discrepancy in band position is observed between grains and grain boundaries, except for the U2(LO) band. We also evidence a difference between the U defect bands and the 885 and 925 cm−1 doublet bands evolution under labelling, although the latter also seems to be connected to the presence of defects in the material.

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Absorption spectrum of single-crystal UO2: Identification of and effect of temperature on the peak positions of essentially all optical transitions in the visible to near infrared regions using derivative spectroscopy

Cited by 22 publications

References 14 publications

Thermal variation of the optical absorption of UO2: determination of the small polaron self-energy

Thermal variation of the optical absorption of UO2: determination of the small polaron self-energy

Raman scattering from phonons and electronic excitations in UO₂with different oxygen isotopes

Isotopic effect of oxygen on the Raman mapping of a polycrystalline uranium dioxide UO₂

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Absorption spectrum of single-crystal UO2: Identification of and effect of temperature on the peak positions of essentially all optical transitions in the visible to near infrared regions using derivative spectroscopy

Cited by 22 publications

References 14 publications

Thermal variation of the optical absorption of UO2: determination of the small polaron self-energy

Thermal variation of the optical absorption of UO2: determination of the small polaron self-energy

Raman scattering from phonons and electronic excitations in UO2with different oxygen isotopes

Isotopic effect of oxygen on the Raman mapping of a polycrystalline uranium dioxide UO2

Contact Info

Product

Resources

About

Raman scattering from phonons and electronic excitations in UO₂with different oxygen isotopes

Isotopic effect of oxygen on the Raman mapping of a polycrystalline uranium dioxide UO₂