钙钛矿型固体电解质Sm_(1-x)Ca_xAlO_(3-δ)的合成与表征

Synthesis and Characterization of Sm_(1-x)Ca_xAlO_(3-δ) Perovskite-type Solid Electrolytes

采用固相反应法合成了纯度较高，杂质含量低的电解质陶瓷Sm1-xCaxAlO3-δ。XRD结果分析表明，Ca掺杂引起了样品晶体结构的转变，x≤0．15的样品为四方钙钛矿结构，而x〉0．15的样品则为菱方钙钛矿相。交流阻抗谱结果表明，掺杂大大提高了样品的电导率，在所有掺杂样品中，Sm0.8Ca0.2AlO3-δ的电导率最高，在800℃时达到0．035S／cm，与同温度下8YSZ的电导率相当。用Sm0.8Ca0.2AlO3-δ作为电解质隔膜，Pt作电极组成了氢-空气燃料电池，并测定了该燃料电池在800～1000℃范围内的电动势（即开路电压）。由实测电动势与Nernst方程导出的理论电动势之比求得的氧离子迁移数在测量温度范围内都大于0．96，并随着温度的升高而逐渐增大。Ca掺杂的SmAlO3是一种性能较为优良的氧离子导体。

The solid electrolytes Sm1-xCaxAlO3-δ with low content of impurity phase were synthesized by solid state reaction method. XRD analysis showed that Ca-doping resulted in structural transformation. The samples of x ≤ 0.15 have tetragonal perovskite structure, but the samples of x 〉 0.15 are rhombohedral phase. Impedance spectra analysis showed that doping of Ca increased the electrical conductivity of the sample significantly. Sm0.8Ca0.2AlO3-δ has the highest conductivity of 0.035S/cm at 800℃ in all the samples, which is equivalent to that of 8YSZ. Using Sm0.8Ca0.2AlO3-δ as a solid electrolyte and Platinum as electrode, hydrogen-air fuel cell was constructed. The electromotive force of the cell was investigated at temperature between 800 and 1000℃ .The oxygen ion transport number was evaluated as the ration of the measured electromotive force to the theoretical value calculated using the Nernst equation. The oxygen ion transport number of Sm0.8Ca0.2AlO3-δ is higher than 0.96 in the temperature region, and increases with increasing temperature. This study reveals that Ca doped SmAlO3 is a kind of oxygen ion conductor with superior properties.