Sc_2O_3稳定ZrO_2多晶离子导体的晶界电导特性研究

Study on Grain Boundary Electrical Properties of Sc_2O_3 Stabilized ZrO_2 Polycrystalline Ionic Conductor

固态离子导体中,杂质在晶界上的偏析是影响离子电导性能的一个重要因素。本工作以掺杂了10.93wt.%Sc_2O_3、1.38wt.%CeO_2的粉体为原料,分别于1300℃、1400℃和1500℃下烧制成片状样品,基于X射线衍射谱的Rietveld全谱拟合计算得到不同温度烧制样品的晶粒尺寸。采用交流阻抗方法研究了各样品的晶粒电阻、晶界电阻和总欧姆电阻随测试温度、晶粒尺寸的变化关系,对相应电导活化能进行了分析。上述研究的结果表明晶界体积占比降低引起该材料的晶界电阻随着晶粒尺寸的增大而减小,而可能存在的晶界杂质偏析在一定程度上抵消了晶界体积占比变化的影响。

The segregation of impurities on the grain boundary in solid state ionic conductor can significantly affects the ionic conduction property. In this work, 10.93 wt.% Sc_2O_3 and 1.38 wt.% CeO_2 doped ZrO_2（SSZ） powder was used as raw materials to be sintered at 1300 ℃, 1400 ℃, and 1500 ℃ respectively to prepare electrolyte plates. The grain size of the sintered samples was calculated based on Rietveld refinements of X-ray diffraction patterns. The evolution of grain resistance, grain boundary resistance and total resistance along with the increased testing temperatures and grain size was investigated using AC impedance method. Also, the grain, grain boundary, and total conductivity activation energy was respectively derived from the results of AC impedance testing. The grain boundary resistance decreased with the increase of grain size due to the decreased volume fraction of grain boundary, whereas the possible impurity segregation at grain boundary was found to be some compensation for the decrease of grain boundary resistance.