Atomic displacement parameters and structural disorder of oxygen ions in the CexZr1−xO2 solid solutions (0.12≤x≤1.0): Possible factors of high catalytic activity of ceria-zirconia catalysts

Crystal structures and electron-density distributions of ceria-zirconia CexZr1−xO2 compounds have been studied by the maximum-entropy method (MEM) and MEM-based pattern fitting combined with the Rietveld method using high-angular-resolution synchrotron x-ray powder diffraction data. The isotropic atomic displacement parameter of the oxygen atoms U(O) in Ce0.5Zr0.5O2 has a maximum value in CexZr1−xO2 (0.12≤x≤1.0). Electron-density distribution of Ce0.5Zr0.5O2 shows a large spatial distribution of the oxygen ions. The greater U(O) and large spatial distribution of oxygen ions in Ce0.5Zr0.5O2 are possible factors of its higher catalytic activity.