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Title: Thermodynamics and Stability of Rhabdophanes, Hydrated Rare Earth Phosphates REPO4 · n H2O

Abstract

Rare earth phosphates comprise a large family of compounds proposed as possible nuclear waste disposal forms. We report structural and thermodynamic properties of a series of rare earth rhabdophanes and monazites. The water content of the rhabdophanes, including both adsorbed and structural water, decreases linearly with increase in ionic radius of the rare earth. The energetics of the transformation of rhabdophane to monazite plus water and the enthalpy of formation of rhabdophane from the constituent oxides was determined by high temperature drop solution calorimetry. The former varies linearly with the ionic radius of the lanthanide, except for cerium. By combining the enthalpy of formation determined by high temperature drop solution calorimetry and the free energy of formation determined previously by solubility experiments, a complete set of thermodynamic data was derived for the rhabdophanes. They are thermodynamically metastable with respect to the corresponding monazites plus water at all temperatures under ambient pressure conditions. This conclusion strengthens the case for monazites being an excellent nuclear waste form.

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Materials Science of Actinides (MSA); Univ. of Notre Dame, IN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1487166
Alternate Identifier(s):
OSTI ID: 1566733
Grant/Contract Number:  
SC0001089
Resource Type:
Published Article
Journal Name:
Frontiers in Chemistry
Additional Journal Information:
Journal Name: Frontiers in Chemistry Journal Volume: 6; Journal ID: ISSN 2296-2646
Publisher:
Frontiers Media SA
Country of Publication:
Switzerland
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; lanthanides; rhabdophanes; monazites; enthalpy; entropy; free energy of formation; stability

Citation Formats

Shelyug, Anna, Mesbah, Adel, Szenknect, Stéphanie, Clavier, Nicolas, Dacheux, Nicolas, and Navrotsky, Alexandra. Thermodynamics and Stability of Rhabdophanes, Hydrated Rare Earth Phosphates REPO4 · n H2O. Switzerland: N. p., 2018. Web. doi:10.3389/fchem.2018.00604.
Shelyug, Anna, Mesbah, Adel, Szenknect, Stéphanie, Clavier, Nicolas, Dacheux, Nicolas, & Navrotsky, Alexandra. Thermodynamics and Stability of Rhabdophanes, Hydrated Rare Earth Phosphates REPO4 · n H2O. Switzerland. doi:10.3389/fchem.2018.00604.
Shelyug, Anna, Mesbah, Adel, Szenknect, Stéphanie, Clavier, Nicolas, Dacheux, Nicolas, and Navrotsky, Alexandra. Mon . "Thermodynamics and Stability of Rhabdophanes, Hydrated Rare Earth Phosphates REPO4 · n H2O". Switzerland. doi:10.3389/fchem.2018.00604.
@article{osti_1487166,
title = {Thermodynamics and Stability of Rhabdophanes, Hydrated Rare Earth Phosphates REPO4 · n H2O},
author = {Shelyug, Anna and Mesbah, Adel and Szenknect, Stéphanie and Clavier, Nicolas and Dacheux, Nicolas and Navrotsky, Alexandra},
abstractNote = {Rare earth phosphates comprise a large family of compounds proposed as possible nuclear waste disposal forms. We report structural and thermodynamic properties of a series of rare earth rhabdophanes and monazites. The water content of the rhabdophanes, including both adsorbed and structural water, decreases linearly with increase in ionic radius of the rare earth. The energetics of the transformation of rhabdophane to monazite plus water and the enthalpy of formation of rhabdophane from the constituent oxides was determined by high temperature drop solution calorimetry. The former varies linearly with the ionic radius of the lanthanide, except for cerium. By combining the enthalpy of formation determined by high temperature drop solution calorimetry and the free energy of formation determined previously by solubility experiments, a complete set of thermodynamic data was derived for the rhabdophanes. They are thermodynamically metastable with respect to the corresponding monazites plus water at all temperatures under ambient pressure conditions. This conclusion strengthens the case for monazites being an excellent nuclear waste form.},
doi = {10.3389/fchem.2018.00604},
journal = {Frontiers in Chemistry},
number = ,
volume = 6,
place = {Switzerland},
year = {2018},
month = {12}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.3389/fchem.2018.00604

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Cited by: 1 work
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