Influence of PbO on SnO2 thick film for sensing properties of toxic gas

In the present paper, we studied the microstructural and sensing behaviors of undoped SnO2 and PbO-doped SnO2 thick film. Three samples have been fabricated using the screen-printing technique on an aluminum substrate and these are S-1 (undoped SnO2) S-2 (1wt% PbO doped SnO2 firing at 800 degrees C), and S-3 (1 wt% PbO doped SnO2 firing at 900 degrees C). XRD and AFM techniques are used to observe the microstructural behaviors and it is found that the crystallite size decreases with PbO doping. The reduction in crystallinity is to improve the sensing application. The sensing properties such as sensing response, selectivity, and transient time of the deposited thick films were studied at an operating temperature of 200 degrees C for various test gases such as ethanol, LPG, and acetone concentrations (0-5000 ppm level). Also, we found that the response of sensor S-3 to the ethanol gas is similar to 3.38 times of LPG and similar to 1.95 times that of acetone gas. The response and recovery times of the ethanol gas for the S-3 sensor are 41s and 125s, respectively. Therefore, the PbO doping improves the response and recovery time for ethanol gas (5000 ppm) over LPG and acetone.