CO sensitivity of La2O3-doped SnO2 thick film gas sensor

Abstract La2O3-doped SnO2 thick films were fabricated via powder mixing of SnO2 and La2O3, and their sensor responses to 10–75 ppm CO were characterized. The presence of La2O3 in a SnO2 thick film containing more than 1.3 at.% La2O3 was confirmed with X-ray diffraction performed at a slow scan rate of 0.5°/min. The sensor response to 50 ppm CO at 350 °C was improved from 9.5 to 59.0 with the addition of 2.2 at.% La2O3 to SnO2. Compared to the CO sensitivity increase of the undoped SnO2 from 3.2 to 37.6, the 2.2 at.% La2O3-doped SnO2 exhibited a remarkable sensitivity improvement from 5.2 to 213.7 with an increase in the CO concentration from 10 ppm to 75 ppm.