Characterization of cubic ceria-zirconia powders by X-ray diffraction and vibrational and electronic spectroscopy

摘要

The X-ray diffraction (XRD) patterns and the Infrared, Raman and UV-visible spectra of CeO_2-ZrO_2 powders prepared by co-precipitation are presented. Raman spectra provide evidence for the largely predominant cubic structure of the powders with CeO_2 molar composition higher than 25 percent. Also skeletal IR spectra allow to distinguish cubic from tetragonal phases which are instead not easily distinguished on the basis of the XRD patterns. All mixed oxides including pure ceria are strong UV absorbers although also absorb in the violet visible region. By carefully selecting their composition and treatment temperature, the onset of the radiation that they cut off can be chosen in the 425-475 nm interval. Although they are likely metastable, the cubic phases are still pure even after heating at 1173 K for 4 h.