DEVELOPMENT OF HIGH-PERFORMANCE SOLID-ELECTROLYTE SENSORS FOR NO AND NO2

This paper demonstrates the development of solid-state NO(x) sensors b ased on various combinations of solid electrolytes and auxiliary sensi ng materials. The Na+ conductor-based sensor fitted with NaNO3 gives r ather good sensing properties to NO,, but this sensor should be operat ed at temperatures below the melting point of NaNO3 (307-degrees-C), i n addition to being incapable of detecting NO. Higher-temperature oper ation is achieved by the use of Ba(NO3)2-based material for the auxili ary sensing electrode. The use of NaNO2 is found to give excellent sen sing characteristics to both NO2 and NO, following Nernst's equation. Surprisingly the NO(x) responses of these sensors are totally independ ent of coexistent oxygen, requiring re-examination of the sensing mech anisms.