Abstract: Ce_0.8Sm_0.2O_1.9-La_9.33Si₆O₂₆ nanocomposite materials were prepared by a two-step coprecipitation synthesis process. Phases and microstructure were investigated by X-ray diffraction and transmission electron microscope. Conductivities were measured by an A.C. impedance measurement system. The results show that the calcined nanocomposites have average grain size of 20nm and the sintered bulks have average grain size of 44nm. The oxideion conductivity of the nanocomposite material is 0.25Ω/cm at 700℃.The conductivities of the nanocomposites are 3 orders higher than that of pure La_9.33Si₆O₂₆ ceramics, which are also higher than that of Ce_0.8Sm_0.2O_1.9 conductor in the test temperatures range. The conducting mechanisms for the nanocomposite ionic conductors are discussed.

Key words: nanocomposite material, coprecipitation synthesis, oxide-ion conductivity