Semiconducting gas sensor for ethanol based on LaMgxFe1−xO3 nanocrystals

The LaMgxFe1−xO3 powder was prepared by a sol–gel method using citric acid. The compounds crystallized as a perovskite phase with orthorhombic structure. The Mg-doping restrained the growth of the grain size. The resistance and gas sensing of the LaMgxFe1−xO3-based sensors were investigated. The Mg-doping decreased the resistance of LaFeO3. The conductivity of LaMgxFe1−xO3 depended on both electrovalence compensation and oxygen vacancy compensation. It was found that the LaMg0.1Fe0.9O3-based sensor had the best response and selectivity to ethanol gas. Great differences on the conductance–temperature curves of the LaMg0.1Fe0.9O3-based sensor in ethanol gas and air or other gases were also found. The conductance in ethanol gas decreased with an increase in temperature from 130 to 200 °C. But in air and other gases the conductance increased all the time. It indicated that at about 200 °C the conductance difference between in air and ethanol was the biggest and the response reached the maximum.