The influence of Zn2+ ions on the microstructure, electrical and gas sensing properties of La0.8Pb0.2FeO3 perovskite

The nanocrystalline La0.8Pb0.2Fe1 − xZnxO3 (x = 0, 0.05, 0.10 and 0.20) powders with orthorhombic perovskite structure were synthesized by a novel self-combustion method using polyvinyl alcohol as colloidal medium. The samples were investigated with regard to their composition and microstructure, using XRD and SEM-EDX methods, their electric properties and gas-sensing properties (resistivity response) to ethanol, acetone and hydrogen. The crystalline lattice constants, the porosity, specific surface area and electric resistivity increase with the increasing amount of zinc ions, which substitute the iron in La0.8Pb0.2FeO3-based perovskite (x = 0). The studied samples show p-type semi-conducting properties for all the studied gases within the temperature range of 100-380 °C. For acetone at the concentration of 400 ppm in the case of the sample with x = 0, the response value is 140; it increases with the increasing quantity of Zn2+ ions up to 560 for x = 0.1, and significantly decreases (down to 45) for x = 0.2. One can state that the sensitivity of La0.8Pb0.2Fe1 − xZnxO3 samples is strongly affected by the amount of Zn2+ ions. The spectacular increase of the response to acetone (560) for the sample with x = 0.1 is remarkable.