skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: The role of surfaces, chemical interfaces, and disorder on plutonium incorporation in pyrochlores

Abstract

Pyrochlores, a class of complex oxides with formula A 2B 2O 7, are one of the candidates for nuclear waste encapsulation, due to the natural occurrence of actinide-bearing pyrochlore minerals and laboratory observations of high radiation tolerance. In this work, we use atomistic simulations to determine the role of surfaces, chemical interfaces, and cation disorder on the plutonium immobilization properties of pyrochlores as a function of pyrochlore chemistry. We find that both Pu 3+ and Pu 4+ segregate to the surface for the four low-index pyrochlore surfaces considered, and that the segregation energy varies with the chemistry of the compound. We also find that pyrochlore/pyrochlore bicrystals A 2B 2O 7/A 2'B 2'O 7 can be used to immobilize Pu 3+ and Pu 4+ either in the same or separate phases of the compound, depending on the chemistry of the material. Finally, we find that Pu 4+ segregates to the disordered phase of an order/disorder bicrystal, driven by the occurrence of local oxygen-rich environments. However, Pu 3+ is weakly sensitive to the oxygen environment, and therefore only slightly favors the disordered phase. This behavior suggests that, at some concentration, Pu incorporation can destabilize the pyrochlore structure. Together, these results provide newmore » insight into the ability of pyrochlore compounds to encapsulate Pu and suggest new considerations in the development of waste forms based on pyrochlores. Particularly, the phase structure of a multi-phase pyrochlore composite can be used to independently getter decay products based on their valence and size.« less

Authors:
ORCiD logo [1];  [1]; ORCiD logo [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1346846
Report Number(s):
LA-UR-16-26968
Journal ID: ISSN 1463-9076; PPCPFQ; TRN: US1701759
Grant/Contract Number:
AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Chemistry Chemical Physics. PCCP (Print)
Additional Journal Information:
Journal Name: Physical Chemistry Chemical Physics. PCCP (Print); Journal Volume: 18; Journal Issue: 33; Journal ID: ISSN 1463-9076
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Perriot, Romain, Dholabhai, Pratik P., and Uberuaga, Blas P.. The role of surfaces, chemical interfaces, and disorder on plutonium incorporation in pyrochlores. United States: N. p., 2016. Web. doi:10.1039/C6CP03543D.
Perriot, Romain, Dholabhai, Pratik P., & Uberuaga, Blas P.. The role of surfaces, chemical interfaces, and disorder on plutonium incorporation in pyrochlores. United States. doi:10.1039/C6CP03543D.
Perriot, Romain, Dholabhai, Pratik P., and Uberuaga, Blas P.. Wed . "The role of surfaces, chemical interfaces, and disorder on plutonium incorporation in pyrochlores". United States. doi:10.1039/C6CP03543D. https://www.osti.gov/servlets/purl/1346846.
@article{osti_1346846,
title = {The role of surfaces, chemical interfaces, and disorder on plutonium incorporation in pyrochlores},
author = {Perriot, Romain and Dholabhai, Pratik P. and Uberuaga, Blas P.},
abstractNote = {Pyrochlores, a class of complex oxides with formula A2B2O7, are one of the candidates for nuclear waste encapsulation, due to the natural occurrence of actinide-bearing pyrochlore minerals and laboratory observations of high radiation tolerance. In this work, we use atomistic simulations to determine the role of surfaces, chemical interfaces, and cation disorder on the plutonium immobilization properties of pyrochlores as a function of pyrochlore chemistry. We find that both Pu3+ and Pu4+ segregate to the surface for the four low-index pyrochlore surfaces considered, and that the segregation energy varies with the chemistry of the compound. We also find that pyrochlore/pyrochlore bicrystals A2B2O7/A2'B2'O7 can be used to immobilize Pu3+ and Pu4+ either in the same or separate phases of the compound, depending on the chemistry of the material. Finally, we find that Pu4+ segregates to the disordered phase of an order/disorder bicrystal, driven by the occurrence of local oxygen-rich environments. However, Pu3+ is weakly sensitive to the oxygen environment, and therefore only slightly favors the disordered phase. This behavior suggests that, at some concentration, Pu incorporation can destabilize the pyrochlore structure. Together, these results provide new insight into the ability of pyrochlore compounds to encapsulate Pu and suggest new considerations in the development of waste forms based on pyrochlores. Particularly, the phase structure of a multi-phase pyrochlore composite can be used to independently getter decay products based on their valence and size.},
doi = {10.1039/C6CP03543D},
journal = {Physical Chemistry Chemical Physics. PCCP (Print)},
number = 33,
volume = 18,
place = {United States},
year = {Wed Jul 27 00:00:00 EDT 2016},
month = {Wed Jul 27 00:00:00 EDT 2016}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 2works
Citation information provided by
Web of Science

Save / Share: