[([Ba.sub.x][La.sub.1-x]).sub.2][In.sub.2][O.sub.5+x] (0.4 [less than or equal to] x [less than or equal to] 0.6) electrolyte-supported mixed-potential CO sensors

The dense ([Ba.sub.x][La.sub.1-x])[sub.2][In.sub.2][O.sub.5+x] electrolytes with different compositions (x = 0.4, 0.5, 0.6) were synthesized by Pechini method. The obtained sintered ([Ba.sub.x] [La.sub.1-x])[sub.2][In.sub.2][O.sub.5+x] electrolytes showed a high relative density of ~98%, and the major phase of three electrolyte compositions was indexed as a cubic phase. The CO sensing properties of as-fabricated planar-type ([Ba.sub.x][La.sub.1-x])[sub.2] [In.sub.2][O.sub.5+x-based sensors coupled with ITO and Pt as the sensing electrode and reference electrode, respectively, were investigated. The effects of factors such as gas flow rate, chemical compositions, and density of the electrolytes on the sensing performance were investigated. The sensors showed good sensitivity to different concentrations of CO from ~100 to ~500 ppm and excellent selectivity over low concentrations of methane (