Sensing performance of lead monoxide-doped tin oxide thick film gas sensor

In this article, we report undoped SnO₂ and PbO-doped SnO₂ thick films to study their microstructural and sensing behaviours. Three samples have been fabricated using a screen-printing technique on an alumina substrate and these are S₁ (undoped SnO₂), S₂ (1 wt% PbO-doped SnO₂ firing at 800°C) and S₃ (1 wt% PbO-doped SnO₂ firing at 900°C). XRD and AFM techniques are used to observe the microstructural behaviours and it is found that the crystallite size decreases with PbO doping. The sensing properties, such as sensing response, selectivity and transient time of the deposited thick films, were studied at an operating temperature of 200°C for various test gases such as ethanol, LPG and acetone concentrations (0–5000 ppm level). Also, we found that the response of sensor S₃ to the ethanol gas is ~3.38 times of LPG and ~1.95 times that of acetone gas. The response and recovery times of the ethanol gas for the S₃ sensor are 41 and 125 s, respectively. Therefore, the PbO doping improves the response and recovery time for ethanol gas (5000 ppm) over LPG and acetone.