A High Pressure X-Ray Diffraction Study of CeO sub 2 to 70 GPa and Pressure Induced Phase Transformation from the Fluorite Structure.
01 January 1988
The crystal structure of CeO sub 2 has been investigated to 70 GPa using energy dispersive x-ray diffraction in a diamond anvil cell. At 3 11.5+-1.0 GPa the fluorite phase transforms, on loading, to an orthorhombic alpha-PbCl sub 2 -like structure of space group P sub (nam) , with a 7.5+-0.7% increase in density. The cubic-flourite phase has a bulk modulus B sub o =230+-10 GPa with an assumed pressure derivative of B' sub o =4.00. The alpha-PbCl sub 4 -type structure seems to be the stable high-pressure 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.