Formation of C-type rare earth structures in the Ce1-xNdxO2-δ system: a factor in the decrease in oxide-ion conductivity

It was found that oxide-ion conductivity of Nd-doped CeO2 (Ce1-xNdxO2-delta/2) increased with in increase in Nd content x up to x = 0.2. showing a maximum value at x = 0.2, and then decreased with x. In order to clarify the origin of the decrease in the conductivity of the heavily Nd-doped CeO2. Rietveld analyses of the X-ray diffraction and neutron diffraction data were carried out, assuming two phases with oxygen deficient fluorite-type and rare-earth C-type structures (0.45 <= x <= 0.7). The oxide-ion conductivity it the heavily Nd-doped CeO2 is discussed in relation to the formation of the rare-earth C-type structure which derives from the oxygen ordering of the defect fluorite-type structure. (C) 2009 The Ceramic Society of Japan All rights reserved