Microstructural and crystallographic effects of sol-gel synthesized Ti-doped UO2 sintered under reducing conditions

Chinthaka M. Silva; Rodney D. Hunt; Andrew T. Nelson

doi:10.1016/j.jnucmat.2021.153003

Microstructural and crystallographic effects of sol-gel synthesized Ti-doped UO₂ sintered under reducing conditions

Chinthaka M. Silva, Rodney D. Hunt, Andrew T. Nelson

Research output: Contribution to journal › Article › peer-review

4 Scopus citations

Abstract

Titanium (Ti)-doped UO₂ microspheres of three different Ti concentrations (1000, 2000, and 4000 wppm) were synthesized using an internal gelation process. The microspheres were pressed into pellets, and a two-step heat treatment was applied to form monolithic cylindrical pellets with high densities (≥95%TD). Microstructure of these samples consisted of equiaxed grains with >300% increase in average grain size compared to the undoped UO₂ pellets. Secondary Ti-rich chemical phases corresponding to a liquid eutectic formed during sintering were observed at grain boundaries of UO₂ for samples doped with 4000 wppm Ti. These Ti-rich chemical phases were not observed in 1000 or 2000 wppm Ti samples at microscale using electron microscopy investigations. The 0.02–0.04% lower lattice parameter values for the Ti-doped UO₂ samples compared to the undoped UO₂ confirms the incorporation of Ti into the UO₂ lattice.

Original language	English
Article number	153003
Journal	Journal of Nuclear Materials
Volume	552
DOIs	https://doi.org/10.1016/j.jnucmat.2021.153003
State	Published - Aug 15 2021

Funding

This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). This work was also performed under the auspices of the U.S. Department of Energy (DOE) by Lawrence Livermore National Laboratory (LLNL) under Contract No. DE-AC52-07NA27344. The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ). This work is supported by the US Department of Energy (DOE) Office of Nuclear Energy , Advanced Fuels Campaign. The paper is authored by UT-Battelle under Contract No. DE-AC05-00OR22725 with the US DOE. This work was also performed under the auspices of the U.S. Department of Energy (DOE) by Lawrence Livermore National Laboratory ( LLNL ) under Contract No. DE-AC52-07NA27344 . The authors would like to acknowledge Rachel Seibert, Alicia Raftery, and Kiel Holliday for their technical reviews and comments on this manuscript.

Funders	Funder number
U.S. Department of Energy
Office of Nuclear Energy
Lawrence Livermore National Laboratory	DE-AC52-07NA27344
UT-Battelle	DE-AC05-00OR22725

Keywords

Grain growth
Lattice parameter
Sol-gel synthesis
TiO-doped UO
Uranium dioxide

Access to Document

10.1016/j.jnucmat.2021.153003

Cite this

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title = "Microstructural and crystallographic effects of sol-gel synthesized Ti-doped UO2 sintered under reducing conditions",

abstract = "Titanium (Ti)-doped UO2 microspheres of three different Ti concentrations (1000, 2000, and 4000 wppm) were synthesized using an internal gelation process. The microspheres were pressed into pellets, and a two-step heat treatment was applied to form monolithic cylindrical pellets with high densities (≥95%TD). Microstructure of these samples consisted of equiaxed grains with >300% increase in average grain size compared to the undoped UO2 pellets. Secondary Ti-rich chemical phases corresponding to a liquid eutectic formed during sintering were observed at grain boundaries of UO2 for samples doped with 4000 wppm Ti. These Ti-rich chemical phases were not observed in 1000 or 2000 wppm Ti samples at microscale using electron microscopy investigations. The 0.02–0.04% lower lattice parameter values for the Ti-doped UO2 samples compared to the undoped UO2 confirms the incorporation of Ti into the UO2 lattice.",

keywords = "Grain growth, Lattice parameter, Sol-gel synthesis, TiO-doped UO, Uranium dioxide",

author = "Silva, {Chinthaka M.} and Hunt, {Rodney D.} and Nelson, {Andrew T.}",

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doi = "10.1016/j.jnucmat.2021.153003",

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AU - Silva, Chinthaka M.

AU - Hunt, Rodney D.

AU - Nelson, Andrew T.

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N2 - Titanium (Ti)-doped UO2 microspheres of three different Ti concentrations (1000, 2000, and 4000 wppm) were synthesized using an internal gelation process. The microspheres were pressed into pellets, and a two-step heat treatment was applied to form monolithic cylindrical pellets with high densities (≥95%TD). Microstructure of these samples consisted of equiaxed grains with >300% increase in average grain size compared to the undoped UO2 pellets. Secondary Ti-rich chemical phases corresponding to a liquid eutectic formed during sintering were observed at grain boundaries of UO2 for samples doped with 4000 wppm Ti. These Ti-rich chemical phases were not observed in 1000 or 2000 wppm Ti samples at microscale using electron microscopy investigations. The 0.02–0.04% lower lattice parameter values for the Ti-doped UO2 samples compared to the undoped UO2 confirms the incorporation of Ti into the UO2 lattice.

AB - Titanium (Ti)-doped UO2 microspheres of three different Ti concentrations (1000, 2000, and 4000 wppm) were synthesized using an internal gelation process. The microspheres were pressed into pellets, and a two-step heat treatment was applied to form monolithic cylindrical pellets with high densities (≥95%TD). Microstructure of these samples consisted of equiaxed grains with >300% increase in average grain size compared to the undoped UO2 pellets. Secondary Ti-rich chemical phases corresponding to a liquid eutectic formed during sintering were observed at grain boundaries of UO2 for samples doped with 4000 wppm Ti. These Ti-rich chemical phases were not observed in 1000 or 2000 wppm Ti samples at microscale using electron microscopy investigations. The 0.02–0.04% lower lattice parameter values for the Ti-doped UO2 samples compared to the undoped UO2 confirms the incorporation of Ti into the UO2 lattice.

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