High-pressure x-ray diffraction study of CeO<SUB>2</SUB> to 70 GPa and pressure-induced phase transformation from the fluorite structure
- Duclos, Steven J.
- Vohra, Yogesh K.
- Ruoff, Arthur L.
- Jayaraman, A.
- Espinosa, G. P.
DOIAbstract
The crystal structure of CeO2 has been investigated to 70 GPa using energy dispersive x-ray diffraction in a diamond-anvil cell. At 31.5±1.0 GPa the fluorite phase transforms, on loading, to an orthorhombic α-PbCl2-like structure of space group Pnam, with a 7.5%±0.7% increase in density. The cubic fluorite phase has a bulk modulus B0=230±10 GPa with an assumed pressure derivative of B0'=4.00. The α-PbCl2-type structure seems to be the stable high-pressure phase in the case of the group-IVB, lanthanide, and actinide fluorite-type dioxides, independent of metal-ion size, at reduced volumes less than 0.89±0.01
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