Catalytic Combustion-Type Hydrogen Sensor Using BaTiO_3-Based PTC Thermistor

摘要

A catalytic combustion-type gas sensor using a positive temperature coefficient (PTC) thermistor, which shows a sharp resistance change around Curie temperature, was developed for the detection of hydrogen. La-doped BaTiO_3 (Ba_(0.998) La_(0.002) TiO_3) was prepared through a solid-state method and an oxalic acid method. La-doped BaTiO_3 obtained by the oxalic acid method showed improved PTC properties, due to the formation of fine particles, as compared to that prepared with the solid-state method. The resulting sensor device showed a fairly high H_2 sensitivity in the range of 100-1000 ppm. In addition, the H_2 sensitivity and response speed were improved by coating a Pt/SiO_2 catalyst on the sensor device because the catalytic combustion efficiency of H_2 was improved by the catalyst coating.