Positional disorder and diffusion path of oxide ions in the yttria-doped ceria Ce0.93Y0.07O1.96

Abstract

The scattering amplitude distribution of an yttria-doped ceria material (Ce_0.93Y_0.07O_1.96, space group: Fmm) has been investigated between 23 and 1434 °C by the maximum-entropy method (MEM) combined with a Rietveld analysis using neutron powder diffraction data. The refined unit cell and atomic displacement parameters increased with an increase in temperature. The results of the MEM analysis reveal that the oxide ions have a positional disorder spreading over a wide area. One possible diffusion path of the oxide ions lies on the tie line along the 〈100〉 directions. The other pathway of the oxide ions can be seen along the 〈110〉 directions. The curved feature in the diffusion path would be common in various ionic conductors.