Naslov
Synthesis and full characterization of the phase-pure pyrochlore Ce2Zr2O7 and the κ-Ce2Zr2O8 phases

Autori
Urban, Sven ; Dolcet, Paolo ; Möller, Maren ; Chen, Limei ; J. Klar, Peter ; Đerđ, Igor ; Gross, Silvia ; M. Smarsly, Bernd ; Over, Herbert

Izvornik
Applied catalysis. B, Environmental (0926-3373) 197 (2016); 23-34

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
kappa phase Ce2Zr2O8 ; pyrochlore Ce2Zr2O7 ; rietveld analysis ; X-ray absorption ; raman spextroscopy

Sažetak
It is known that the -Ce2Zr2O8 phase is an active oxidation catalyst with an extraordinarily high oxygen storage capacity. The -Ce2Zr2O8 phase is synthesized starting from t-Ce0.5Zr0.5O2 solid solution which is reduced by hydrogen at high temperatures to form the pyrochlore Ce2Zr2O7 phase (pyr-Ce2Zr2O7) with high degree of ordering of the cationic sublattice. The final step in the synthesis of the -Ce2Zr2O8 phase includes a mild re-oxidation of pyr-Ce2Zr2O7 at around 600 °C under atmospheric conditions. Yet, the optimum synthesis of the -Ce2Zr2O8 phase is still not settled since most of the previous studies used reduction temperatures of 1300 °C and below. We show in contribution that 1300 °C is not sufficient to warrant the preparation of phase-pure pyr-Ce2Zr2O7 and -Ce2Zr2O8, but rather that temperatures as high as 1500 °C are required to assure phase purity. This conclusion is drawn from extended X-ray diffraction and X-ray absorption spectroscopy analysis together with Raman spectroscopy, providing in-depth details of the structure on the level of both, the evolution of the special periodic structure and the coordination of the metal atoms.

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Kemija

POVEZANOST RADA