Solid solutions Ce_1－xNd_xO_2－δ (x＝0.05～0.55) were prepared by sintering the gel at 800 ℃ for 10 h by sol-gel method. XRD showed that solid solutions Ce_1－xNd_xO_2－δ were crystallized in a cubic fluorite structure. The electron paramagnetic resonance spectra suggested that the content of Ce^3＋ ions is decreased with the increasing dopant content x in the solid solutions Ce_1－xNd_xO_2－δ, which suggested that doping with lower valence Nd^3＋ ions may control the redox of Ce^4＋ ions in the solid solutions. The impedance spectra of the solid solutions showed ionic conduction. The conductivities of Ce_0.9Nd_0.1O_2－δ were 4.25×10^－3 and 1.12×10^－2 S•cm^－1 at 600 and 700 ℃ respectively, and activation energy was 0.82 eV.

Key words: sol-gel method, solid solution Ce_1－xNd_xO_2－δ, EPR spectrum, conductivity