Selectivity between methanol and ethanol gas of La–Pb–Fe–O perovskite synthesized by novel method

Rare earth oxide La0.8Pb0.2FeO3 was synthesized by a novel self-combustion method using polyvinyl alcohol as colloidal medium. The X-ray diffraction pattern (XRD) showed that La0.8Pb0.2FeO3 oxides are single phase with orthorhombic perovskite structure; they all show p-type semiconducting properties. The gas response characteristics were obtained by measuring the sensitivity as a function of various factors like operating temperature, type and concentration of the test gas and, finally, the response time. Carbon dioxide, hydrogen, methanol, ethanol and butane were used as test gases. The La0.8Pb0.2FeO3 sensors have the best response to methanol and ethanol gas. The response to hydrogen is much smaller and it is negligible for carbon dioxide and butane. A big sensitivity between methanol and ethanol gas was obtained at different operating temperatures, even though the two alcohols have very similar properties. At a concentration of 400 ppm gas at the operating temperature of 230 °C, the response to methanol is 146.6, and to ethanol is 25. At operating temperature of 280 °C, the response to ethanol is 133.3, and to methanol is 18. The same sensor can be used as selective sensor for either methanol or ethanol by simply modifying the operating temperature.