FACTORS DETERMINING THE CARBON-MONOXIDE SENSING PROPERTIES OF TIN OXIDE THICK-FILMS CALCINED AT DIFFERENT TEMPERATURES

Effects of calcination temperature on the gas-sensing properties of Sn O2 thick films mere explored by measuring the variations in resistance with CO concentration. As the calcining temperature increased from 50 0 degrees to 1100 degrees C, the absolute values of the slopes in the log (concentration) vs log (resistance) curves gradually decreased fro m -0.9 to -0.2. The data were analyzed with the equations proposed by Madou and Morrison. It was suggested that the reduction in the formati on rate of oxygen adsorbates was responsible for the decrease in the a bsolute slope, and hence a relatively high sensitivity was attained in a low gas concentration with a largely crystallized sample.