Chemical Tuning versus Microstructure Features in Solid-State Gas Sensors: LaFe1-xGaxO3, a Case Study

A simple and cheap wet chemical approach is exploited to synthesize LaFe1-xGaxO3 (x = 0-1) crystalline perovskites. Ga doping level deeply influences not only the microstructure, but also the iron chemical features and consequently the responses to external chemicals. Sensitivity toward gases (NO2, CO, and ethanol), in fact, is driven by both Fe/Ga ratio and iron oxidation states, which are demonstrated playing a role much stronger than morphological parameters, such as grain size and specific surface area, usually dominating the performances of metal oxide based gas sensors. Results highlight that sensing behavior is tunable within a large extent by a simple and effective modulation of the chemical composition, obtaining sensitivities comparable with state of the art perovskite based gas sensors.