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Published April 24, 2013 | public
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Anomalous bulk compression behaviour in a hyperstoichiometric uranium-dioxide–thorium-dioxide solid solution

Tschauner, O. ORCID icon
Ma, C. ORCID icon
Grubor-Urosevic, O.
Chen, Y. J.
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Abstract

The compression behaviour of a solid solution of ThO_2 and hyperstoichiometric UO_2 was examined up to 11 GPa hydrostatic pressure using x-ray diffraction. We observed a distortive phase transition above 3 GPa from fluorite-type to a structure isotypic with t-zirconia. The transition is tentatively explained by merging of local tetragonal UO_(2+δ) clusters into an itinerant structural distortion. The bulk modulus increases from 162 ± 1 to 199 ± 4 GPa in the tetragonal phase by stiffening of the c-axis compression.

Additional Information

© 2013 Institute of Physics Publishing Ltd. Received 10 December 2012, in final form 19 February 2013. Published 18 March 2013. This research was supported by NNSA Cooperative Agreement DE-FC88-01NV14049. CHESS is supported by the NSF and NIH/NIGMS via NSF award DMR-0936384. We acknowledge support by P Sorensen and Z Wang at CHESS. The SEM and EPMA analyses were carried out at the Caltech GPS Division Analytical Facility, which is supported, in part, by NSF Grants EAR-0318518 and DMR-0080065.

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August 19, 2023
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October 23, 2023