EXAFS study of reduced ceria doped with lanthanide oxides

The local structures around Ce and Ln atoms in Ce1−xLnxO2.00−y (Ln=Y; x=0.05–0.30, Gd; x=0.10–0.30, Sm and Yb; x=0.20 and 0.30) were studied by extended X-ray absorption fine structure (EXAFS) spectroscopy. The Ce–O inter-atomic distances decreased with increasing oxygen deficiency caused by increasing the dopant content and reducing the valence of Ce in the samples. The Ce–O distances of reduced samples further decreased at high temperature. The Ln–O (Ln=Y, Gd and Yb) distances also decreased with increasing oxygen deficiency. The local structures of doped and reduced ceria were discussed in view of the phase stability of the samples.