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Title: Characterizing the degradation of [(UO2F2)(H2O)]7 4H2O under humid conditions

Abstract

Under humid conditions, uranyl fluoride ([(UO2F2)(H2O)]7·4H2O) undergoes a loss of fluorine to form a uranyl hydroxide species, which can be further hydrated to form a uranyl peroxide species. X-ray diffraction data of the uranyl peroxide product is presented for the first time. In addition, the temperature and humidity conditions under which these reactions occur have been clarified by a 220-day experiment using microRaman spectroscopy to track chemical changes in individual particles of uranyl fluoride. At 25 and 35°C, uranyl fluoride is found to be stable at 32% relative humidity but not stable at and above 59% relative humidity. We show that water vapor pressure is the driving factor in formation of both the hydroxide and peroxide products. The kinetics of the transformation from uranyl fluoride into uranyl hydroxide is consistent with a denucleation reaction following the absorption of water molecules.

Authors:
 [1]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1607037
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 529; Journal Issue: C; Journal ID: ISSN 0022-3115
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; uranyl flouride; uranyl hydroxide; uranyl peroxide; uranium; raman spectroscopy; x-ray diffraction; relative humidity; degradation

Citation Formats

Kirkegaard, Marie C., Ambrogio, Michael W., Miskowiec, Andrew J., Shields, Ashley E., Niedziela, Jennifer L., Spano, Tyler L., and Anderson, Brian B.. Characterizing the degradation of [(UO2F2)(H2O)]7 4H2O under humid conditions. United States: N. p., 2019. Web. https://doi.org/10.1016/j.jnucmat.2019.151889.
Kirkegaard, Marie C., Ambrogio, Michael W., Miskowiec, Andrew J., Shields, Ashley E., Niedziela, Jennifer L., Spano, Tyler L., & Anderson, Brian B.. Characterizing the degradation of [(UO2F2)(H2O)]7 4H2O under humid conditions. United States. https://doi.org/10.1016/j.jnucmat.2019.151889
Kirkegaard, Marie C., Ambrogio, Michael W., Miskowiec, Andrew J., Shields, Ashley E., Niedziela, Jennifer L., Spano, Tyler L., and Anderson, Brian B.. Mon . "Characterizing the degradation of [(UO2F2)(H2O)]7 4H2O under humid conditions". United States. https://doi.org/10.1016/j.jnucmat.2019.151889. https://www.osti.gov/servlets/purl/1607037.
@article{osti_1607037,
title = {Characterizing the degradation of [(UO2F2)(H2O)]7 4H2O under humid conditions},
author = {Kirkegaard, Marie C. and Ambrogio, Michael W. and Miskowiec, Andrew J. and Shields, Ashley E. and Niedziela, Jennifer L. and Spano, Tyler L. and Anderson, Brian B.},
abstractNote = {Under humid conditions, uranyl fluoride ([(UO2F2)(H2O)]7·4H2O) undergoes a loss of fluorine to form a uranyl hydroxide species, which can be further hydrated to form a uranyl peroxide species. X-ray diffraction data of the uranyl peroxide product is presented for the first time. In addition, the temperature and humidity conditions under which these reactions occur have been clarified by a 220-day experiment using microRaman spectroscopy to track chemical changes in individual particles of uranyl fluoride. At 25 and 35°C, uranyl fluoride is found to be stable at 32% relative humidity but not stable at and above 59% relative humidity. We show that water vapor pressure is the driving factor in formation of both the hydroxide and peroxide products. The kinetics of the transformation from uranyl fluoride into uranyl hydroxide is consistent with a denucleation reaction following the absorption of water molecules.},
doi = {10.1016/j.jnucmat.2019.151889},
journal = {Journal of Nuclear Materials},
number = C,
volume = 529,
place = {United States},
year = {2019},
month = {11}
}

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