MANUFACTURE OF NITROGEN OXIDES DETECTING ELEMENT

摘要

PROBLEM TO BE SOLVED: To provide an NOX detecting element which is durable even in a very severe environment which becomes a high-temperature and strongly acidic or reducing atmosphere such as in the exhaust pipe of an automobile and by which NOX can be detected with sufficient sensitivity. SOLUTION: An alloy film having a thickness of 0.4 to 3 μm is manufactured of an alloy in which niobium and/or tantalum in 4 to 25 atomic % are added to titanium. The alloy film is heat-treated at 900 to 1000 deg.C in an atmosphere whose oxygen concentration is lower than that of the air. A nitrogen oxides detecting element which is composed of a filmlike detection part (a nitrogen oxides detecting film 3) composed mainly of titanium oxide is obtained. As a result, while the stability as an oxide of the titanium oxide is being kept, the electric property of the titanium oxide as an insulator is improved, and an oxide film which is suitable as a resistance change-type NOX detecting element can be obtained.