Highly water vapor-durable solid electrolyte type ammonia gas sensor with ammonium rare earth niobate as an auxiliary sensing electrode

A solid electrolyte-type ammonia (NH 3 ) gas sensor with high durability for water vapor was devised by combining a trivalent Al 3+ ion-conducting solid electrolyte and ammonium lanthanum niobate (NH 4 LaNb 2 O 7 ).The present sensor, using NH 4 LaNb 2 O 7 as the auxiliary sensing electrode, detected NH 3 gas concentration by obeying the theoretical Nernst relationship even at 180 C.The present sensor exhibited a quantitative response to NH 3 gas concentration change without the influence of water vapor even in a highly humid atmosphere containing 4.2 vol% H 2 O for over 3 months, indicating that the sensor with the NH 4 LaNb 2 O 7 auxiliary sensing electrode was revealed to possess an extraordinarily high water vapor durability.