The development of multivalent ion conductors and their application for chemical sensors

New types of multivalent ion conducting solid electrolytes have been extensively developed and their applications for chemical sensors were investigated. Among the trivalent ion conductors, the highest ion conductivity was realized with the (Al_xZr_1−x)_4/(4−x)Nb(PO₄)₃ solid electrolyte and the value reaches the region between yttria stabilized zirconia (YSZ) and calcia stabilized zirconia (CSZ) of the representative oxide anion conductors. The above described Al³⁺ ion conducting (Al_xZr_1−x)_4/(4−x)Nb(PO₄)₃ solid electrolyte was combined with YSZ, with accompanying the Y₂O₃-KNO₂ solid solution as an auxiliary electrode for nitrogen monoxide (NO) gas sensing. The sensor response was rapid and a reproducible output was continuously observed obeying the Nernst theoretical relationship in a typical NO gas content region in exhaust gases. Paper presented at the 9th EuroConference on Ionics, Ixia, Rhodes, Greece, Sept. 15 – 21, 2002.