Positional disorder of oxygen ions in ceria at high temperatures

Accurate nuclear density distribution of ceria, CeO2 has been studied between 1005 and 1497 °C by the maximum-entropy method-based pattern fitting combined with the Rietveld method using neutron powder diffraction data. The results reveal that the oxygen ions have a complicated disorder spreading over a wide area and shift to the 〈111〉 directions from the ideal fluorite position. This feature is more significant at higher temperatures, which is consistent with the higher ionic conductivity.