The high-pressure study of nanocrystalline CeO2

The structure and properties of the nanosized CeO2 under high pressure have been investigated by synchrotron X-ray diffraction in the diamond anvil cell combined with the first-principle methods based on density functional theory. The experimental data demonstrate that nanosized CeO2 is highly stable upto 31.3 GPa and bulk modulus is 213 +/- 3 GPa. The calculated results by LDA + U indicate that CeO2 undergoes structural transition from cubic fluorite-type structure to orthorhombic alpha-PbCl2-type structure at 20 GPa. The indirect band gap (R -> G) is 1.89 eV and increases with the increasing pressure while it suddenly reduces to 1.62 eV at transition pressure. The transition pressure calculated by GGA is 40.3 GPa.