NOx Sensing Properties of Metal Titanate Based Semiconductor Sensor at Elevated Temperature

A series of metal titanates was examined for their NOx sensing properties at elevated temperatures of 500-600℃. As a result, BaTiO3 and SrTiO3 sensors were found to be rather sensitive to NO and/or NO2 existing in air at 600 and 500℃, respectively, together with practically acceptable response and recovery rates. At these temperatures, both sensors exhibited almost linear sensitivity-NOx concentration correlations in the concentration range of 5-100ppm.The electrical resistance of SrTiO3 sensor at 500℃was almost independent of oxygen concentration in the range of 3-15％and scarcely affected by interfering gases such as CO2, H2, and C3H6. The NOx sensing mechanism of this element was briefly discussed