Study on zirconia solid electrolytes doped by complex additives

Yttria stabilized zirconia (YSZ) possesses an adequate level of oxygen ion conductivity and exhibits desirable chemical stability in both oxidizing and reducing atmospheres, and is widely used as an electrolyte for solid oxide fuel cells. We reported here the effects of Sc2O3 or Dy2O3 addition on the electrical conductivity, sintering, bending strength and microstructure of Sc2O3 or Dy2O3 and Yb2O3 doped-YSZ electrolyte materials prepared by high-temperature solid-state method. The electrical conductivity of the electrolyte materials was significantly improved by taking advantage of a complex addition of Y2O3, Yb2O3 and Sc2O3 (or Dy2O3) and maximum values of 0.18 and 0.16 S/cm were obtained at 1000 °C for both Series I and II, respectively, when the total additive content was 8.3 mol%. In addition, the bulk densities (1600 °C, 4 h) of the sintered samples decreased from 5.82 to 5.24 g/cm3 with the increase of Sc2O3 content but increased from 5.63 to 5.86 g/cm3 as Dy2O3 content increased following the same sintering conditions. The findings of this research also suggest that the introduction of complex additives promotes grain growth to a certain extent. The sample with Dy2O3 had larger grain sizes than that with Sc2O3.