Ab initio Raman-spectroscopic study on Ce-Zr-oxides

Mixed Zr-Ce-oxides may serve as oxygen-storing co-catalysts in automotive applications or as catalytically active species in oxidation reactions. Amongst these, κ-Ce₂Zr₂O₈ is particularly known for its excellent oxygen storage capacity (OSC). This phase may be obtained from the so-called pyrochlore phase pyr-Ce₂Zr₂O₇ by incorporating oxygen, thereby oxidizing Ce³⁺ to Ce⁴⁺. The underlying structural transition form the pyrochlore to the κ-phase is the key to understanding the superb OSC. Being very sensitive to structural differences, Raman spectroscopy is a well-suited method for investigating differences between crystal phases on a structural, electronic and vibrational level. Hence, in order to understand structural as well as electronic differences of both phases we calculate Raman susceptibilities and derived spectra based on DFT calculations. With our theoretical results we aim to interpret experimental Raman spectra.