Microstructure of Rare-Earth-Doped Ceria Prepared by Oxalate Coprecipitation Method

Abstract

Rare-earth-doped ceria powders (Ce_0.8R_0.2O_1.9, R=Yb, Y, Gd, Sm, Nd and La), prepared by oxalate coprecipitation, were sintered at 1600°C in air. All X-ray diffraction patterns of the samples could be indexed as those of a cubic fluorite structure. The measured lattice parameter and density were well explained by the oxygen vacancy model associated with the substitution of a rare-earth-dopant for cerium. The observation of rare-earth-doped ceria ceramics by high-resolution transmission electron microscopy indicated that no crystalline or amorphous secondary phase formed in the grain interior or at grain boundaries. The rare-earth-dopant elements dissolved uniformly in the bulk and at grain boundaries.