(LSO) have been synthesized by a modified coprecipitation method. X-ray diffraction, electron microscope, and complex impedance were adopted to investigate the phase component, microstructures, and conductivities, respectively. The results show that the average grain sizes of the composite powders and as-sintered pellets are less than 20 nm and 200 nm, respectively. The conductivity of the composite materials composed of 94 wt% YSZ and 6 wt% LSO is 0.215 S/cm at 700 ℃. The conductivity of the composite is three times higher than that of the polycrystalline YSZ and has two orders in magnitude higher than that of the polycrystalline LSO at 700 ℃. By analyzing the impedance spectra and modulus spectra, the grain-boundary effect on the conductivity improvement is investigated and the conductive mechanisms of the composite materials are discussed.

To improve the conductivity of Y 2 O 3 -stabilized ZrO 2 (YSZ) based oxygen-ion conductor, Zr 0.85 Y 0.15 O 1.925 -La 9.33 Si 6 O 26 (YSZ-LSO) composite ceramics with the mass fraction of La 9.33 Si 6 O 26 (LSO) of 15% were prepared by using a modified coprecipitation method. The phases, microstructures and conductivities of the YSZ, LSO and YSZ-LSO were investigated by X-ray diffraction, electron microscopy and complex impedance, respectively. The results show that the as-calcined powder of YSZ-LSO composite has the grain size less than 10 nm, and the as-sintered composite ceramics are composed of YSZ and LSO phases. The conductivity can be enhanced obviously by composite method. At 700 °C, the conductivity of the composite ceramic is 0.125 S/cm, which is one order in magnitude higher than that of the YSZ ceramic and two orders in magnitude higher than that of LSO ceramic. By analyzing the impedance spectra and modulus spectra, the interfacial effect on the conductivity improvement was proposed.

No abstract