Ionic conductivity and its temperature dependence of atmospheric plasma-sprayed yttria stabilized zirconia electrolyte

In this study, yttria stabilized zirconia (YSZ) electrolytes were deposited using 8 mol% and 4.5 mol% YSZ powders by atmospheric plasma spraying (APS). The ionic conductivity of the obtained YSZ electrolytes was measured by the means of DC measurement and AC impedance spectroscopy, in a temperature range of 600-1000 °C. The ionic conductivity of 8 mol% YSZ coating is about 50% higher than that of 4.5 mol% YSZ coating. Furthermore, for the same specimen, the ionic conductivity in the parallel direction is about twice higher than that in perpendicular direction. The anisotropy of the ionic conductivity is attributed to the APS coating structure characteristics. In the studied temperature range, a significant temperature dependence of ionic conductivity was observed for the two electrolytes. The traditional Arrhenius equation was employed to analyze the ionic conductivity data and the non-linear Arrhenius behavior was observed. The intragrain-intergrain conductivity model and dissociation-migration energy model were employed to discuss the observed temperature dependency of electrical conductivity of plasma-sprayed YSZ deposits, and the dissociation-migration energy model was more reasonable to explain this temperature dependence.