Phase evolution and reduction behavior of Ce0.6Zr0.4O2 powders prepared using the chemical co-precipitation method

The relationship between the crystalline structure and reduction behavior of Ce0.6Zr0.4O2 (C60Z) synthesized using the chemical co-precipitation method is investigated. C60Z decomposes into Ce-rich and Zr-rich phases after calcination at above 1100 °C for 2 h. The phase separation deteriorates the reducibility and oxygen storage capacity, indicating that reduction behavior is degraded by chemical inhomogeneity due to phase separation. The two separated phases transform into pyrochlore after heat treatment at 1490 °C under a 5% CO/N2 atmosphere and then transform back into the separated phases after subsequent heat treatment in air. These results suggest that the structural change under reduction/re-oxidation treatment may result from cation diffusion.