Potentiometric Oxygen Sensor Operable in Low Temperature by Applying LaGaO3‐Based Oxide for Electrolyte

Oxygen sensors are important for combustion control, in particular, for vehicles. A perovskite-type oxide of LaGaO{sub 3} doped with Sr and Mg exhibits a high oxide ion conductivity over a wide range of oxygen partial pressures. In this study, the application of LaGaO{sub 3}-based oxide as the electrolyte of a potentiometric oxygen sensor was investigated. It became clear that silver is the most effective electrode for decreasing the operating temperature. Although a temperature higher than 800 K is required when a conventional Y{sub 2}O{sub 3}-stabilized ZrO{sub 2} electrolyte is used, an operating temperature as low as 600 K is adequate when La{sub 1{minus}x}Sr{sub x}Ga{sub 0.8}Mg{sub 0.2}O{sub 3} at X = 0.1 and 0.2 is used. The open-circuit potential was slightly smaller than that estimated with the Nernst equation. There was agreement with the Nernst equation down to 673 K when Nd-doped LaGaO{sub 3}-based oxide was used. Moreover, 90% of the response was attained within 15 s at 673 K for the sensor with Nd-doped LaGaO{sub 3}-based oxide.