Structure and bulk modulus of Ln-doped UO2 (Ln = La, Nd) at high pressure

Dylan R. Rittman, Sulgiye Park, Cameron L. Tracy, Lei Zhang, Raul I. Palomares, Maik Lang, Alexandra Navrotsky, Wendy L. Mao, Rodney C. Ewing

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

The structure of lanthanide-doped uranium dioxide, LnxU1-xO2-0.5x+y (Ln = La, Nd), was investigated at pressures up to ∼50–55 GPa. Samples were synthesized with different lanthanides at different concentrations (x ∼ 0.2 and 0.5), and all were slightly hyperstoichiometric (y ∼ 0.25–0.4). In situ high-pressure synchrotron X-ray diffraction was used to investigate their high-pressure phase behavior and determine their bulk moduli. All samples underwent a fluorite-to-cotunnite phase transformation with increasing pressure. The pressure of the phase transformation increased with increasing hyperstoichiometry, which is consistent with results from previous computational simulations. Bulk moduli are inversely proportional to both the ionic radius of the lanthanide and its concentration, as quantified using a weighted cationic radius ratio. This trend was found to be consistent with the behavior of other elastic properties measured for Ln-doped UO2, such as Young's modulus.

Original languageEnglish (US)
Pages (from-to)28-33
Number of pages6
JournalJournal of Nuclear Materials
Volume490
DOIs
StatePublished - Jul 1 2017
Externally publishedYes

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Materials Science(all)
  • Nuclear Energy and Engineering

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