PURPOSE: To enable selectively detecting NO even when O2 is present in the atmosphere by providing the element with an electrode, on a piezoelectric substrate, that excites elastic wave and a catalyzer that adsorbs NO.
CONSTITUTION: On bath ends of one surface of a piezoelectric substrate 1, formed in rectangular of LiNbO3, and having its thickness about 0.5mm, a pair of comb-like electrodes 2 and 3, made of Au, that excites elastic wave is formed. Electrodes 2 and 3 are connected to load wires 4 and 5 with Au paste. Further, a YBa2Cu3O7 thin film, a composite oxide containing Cu, is formed as a catalyser 6 that selectively adsorbs NO and excellent in heat resistance, on an elastic wave propagation path of the substrate 1 by thickness of about 5000. This composite oxide is excellent in heat resistance, its structure does not change even at 500°C. By making the nitrogen oxide detecting element contact to the mixture gas of NO, O2 of various concentrations, and heating it, accurate NO concentration is detected even when the atmosphere contains O2.
NAGAI TAKESHI
TABATA KENJI
TSURUTA KUNIHIRO
OCHI KENZO
