Covalent insulatorCeO2: Optical reflectivity measurements

Abstract
The optical reflectivity of CeO2 single crystals has been measured from 1 meV to 12 eV at 300 K and then analyzed in terms of a Kramers-Kronig transformation. Static and optic dielectric constants, TO- and LO-phonon frequencies, the effective charge, and the degree of covalency have been obtained. It can be asserted that CeO2 is not of intermediate valence but it is a covalent insulator.