Structural disorder in the cubic Ce0.5Zr0.5O2 catalyst: A possible factor of the high catalytic activity

Nuclear-density distribution of cubic Ce0.5Zr0.5O2 compound has been studied at 1832K by the maximum-entropy method (MEM) and MEM-based pattern fitting combined with the Rietveld method using in situ neutron powder diffraction data. The oxygen ions show a large positional disorder and shift to the ⟨111⟩ directions. Possible bulk diffusion paths of the oxygen ions can be seen along the ⟨100⟩ and ⟨110⟩ directions. The spatial distribution of oxygen ions in Ce0.5Zr0.5O2 is greater than that of CeO2, which is consistent with the higher bulk diffusivity of oxygen ions in Ce0.5Zr0.5O2. It is suggested that the greater disorder of Ce0.5Zr0.5O2 is a factor of its higher catalytic activity.