Developement of High Oxide Ion Conductors Based on Stabilized Zirconia

从固体氧化物燃料电池的应用角度出发，研究了Sc_2O_3-ZrO_2系统的氧离子电导率和力学性能。氧化钪掺杂氧化锆体系的氧离子电导率最高。低含量Sc_2O_3（8mol%）的样品在1000 ℃退火后电导率明显下降，而高含量Sc_2O_3（11mol%和12mol%）的样品在1000 ℃退火后电导率没有变化。借助XRD和拉曼散射技术研究了退火引起的相变。在室温和更高温度下测量烧结样品的弯曲强度。此外，还研究了（ZrO_2）_<0.89>（Sc_2O_3）_x（Y_2O_3）_和<0.11-x>（ZrO_2）_<0.89>（Sc_2O_3）_x（Yb_2O_3）_<0.11-x>系统的相关系和电导率随x的变化。后一种体系的电导率略高于前一种体系。(ZrO Yb <0.89><0.11>^&lt;3+&gt;或Y^&lt;3+&gt;对（ZrO_2）_（Sc_2O_3）_中Sc^&lt;3 +&gt;的取代使（ZrO_2）_<0.89>（Sc_2O_3）_<0.11>的高温立方相稳定到室温。这些系统在1000 ℃退火时没有表现出电导率下降。

Oxide ion conductivity and mechanical properties of Sc_2O_3-ZrO_2 system have been studied in view point of an application to solid oxide fuel cells. The scandia doped zirconia system showed the hightest oxide ion conductivity in the zirconia system. The solid solution with low content of Sc_2O_3 as 8mole% showed a significant conductivity degradation with annealing at 1000ﾟC.On the other hand, bno conductivity change was observed in the samples with higher content of Sc_2O_3 as 11 and 12 mole%. The phase change by annealing has been examined with help of XRD and Raman scattering technique. The bending strength of the sintered samples was measured at room temperature and higher temperatures. The scandia doped zirconia showed almost same bending strength to that of yttria doped zirconia.Moreover, the phase relation and electrical conductivity of the (ZrO_2)_<0.89>(Sc_2O_3)_x(Y_2O_3)_<0.11-x> and (ZrO_2)_<0.89>(Sc_2O_3)_x(Yb_2O_3)_<0.11-x> system have been examined as a function of x. The latter system had slightly higher conductivity than the former system. (ZrO_2)_<0.89>(Sc_2O_3)_<0.11> has the rhombohedral structure at room temperature, which is transformed to cubic structure at 580ﾟC.The substitution of Yb^<3+> or Y^<3+> for Sc^<3+> in (ZrO_2)_<0.89>(Sc_2O_3)_<0.11> stabilized at the high temperature cubic phase to room temperature. These system exhibited no conductivity degradation by annealing at 1000ﾟC.