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Title: Structure and bulk modulus of Ln-doped UO 2 (Ln = La, Nd) at high pressure

The structure of lanthanide-doped uranium dioxide, Ln xU 1-xO 2-0.5x+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. As a result, this trend was found to be consistent with the behavior of other elastic properties measured for Ln-doped UO 2, such as Young's modulus.
Authors:
ORCiD logo [1] ;  [1] ; ORCiD logo [1] ;  [2] ; ORCiD logo [3] ;  [3] ;  [2] ;  [4] ;  [1]
  1. Stanford Univ., Stanford, CA (United States)
  2. Univ. of California, Davis, CA (United States)
  3. Univ. of Tennessee, Knoxville, TN (United States)
  4. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Grant/Contract Number:
AC02-76SF00515; SC0001089; NA0001974; FG02-99ER45775; AC02-05CH11231; EAR 1606856; NA0002006
Type:
Accepted Manuscript
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 490; Journal Issue: C; Journal ID: ISSN 0022-3115
Publisher:
Elsevier
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1369255
Alternate Identifier(s):
OSTI ID: 1419350