title: Anomalous bulk compression behaviour in a hyperstoichiometric uranium-dioxide-thorium-dioxide solid solution.
abstract: The compression behaviour of a solid solution of ThO2 and hyperstoichiometric UO2 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.
authors.affiliation: High Pressure Science and Engineering Center, UNLV, NV, USA.
authors.forename: O
authors.initials: O
authors.lastname: Tschauner
authors.forename: C
authors.initials: C
authors.lastname: Ma
authors.forename: O
authors.initials: O
authors.lastname: Grubor-Urosevic
authors.forename: Y J
authors.initials: YJ
authors.lastname: Chen