Perovskite Electrodes for Zirconia Electrolytic Cells

固体氧化物电解质提供了导电的前景 高温和反应环境下的电化学; 本发明的一个应用是用于监测燃烧中的氧气水平 废气流。 现有的系统使用沉积的多孔金属膜 在固体电解质上;虽然功能性，但这种系统具有低的 效率，显然是因为只有三相（金属， 电解质、气体）边界是活跃的。 本研究旨在克服 这个问题通过使用金属氧化物来解决， 电子和氧离子。 特别是氧气的动力学 气相和电解质族之间的交换， 钙钛矿结构，掺镧钙钛矿 （LaxCa 1-xMnO 3）的结构。 电子和离子性质可以 可以通过改变掺杂水平来改变。用于制备这些的技术 有用形式的材料将得到完善。电化学动力学 使用稳态和瞬态电化学 技术;电导率使用AC阻抗方法测量; 表面化学是用程序升温 解吸和俄歇电子能谱。 这项研究可能会产生非常广泛的影响。 最直接的影响 将用于使用氧传感器的系统，包括用于 汽车尾气排放控制， 焚化 这项工作应减少规模，扩大 有用的温度范围，并提高这些灵敏度 传感器. 类似的电极在燃料电池中应该是有用的， 电解槽和其它电化学装置。 这项工作是 也适用于其他高性能陶瓷，特别是 密切相关的“缺陷钙钛矿超导体。"

Solid-oixide electrolytes offer the prospect of conducting electrochemistry at high temperatures and in reactive environments; one present application is for monitoring oxygen levels in combustion exhaust streams. Existing systems use porous metallic films deposited on solid electrolytes; while functional, such systems have low effeciency, apparently because only the three-phase (metal, electrolyte, gas) boundary is active. This study seeks to overcome this problem by use of metal oxides that exhibit conductivity for both electrons and oxygen ions. Specifically, the kinetics of oxygen exchange between the gas phase and a family of electrolytes with the perovskite structure, lanthanum-doped calcium manganate (LaxCa1-xMn03), is investigated. Electronic and ionic properties can be varied by changing the doping level. Techniques for preparing these materials in useful forms will be perfected. Electrochemical kinetics are measured using steady-state and transient electrochemical techniques; conductivities are measured using AC impedance methods; and surface chemistry is probed using temperature-programmed desorption and Auger election spectroscopy. This study could have very wide impact. The most immediate impact will be in systems using oxygen sensors including control systems for automotive carburetion and exhaust control, and for incineration. This work should reduce the size, extend the useful temperature range, and improve the sensitivity of these sensors. Similar electrodes should be useful in fuel cells, electrolyzers, and other electrochemical devices. The work is also applicable to other high-performance ceramics, notably the closely related "defect perovskite superconductors."