LaFeO3 ceramics as selective oxygen sensors at mild temperature

In this study, an investigation about the oxygen sensing properties of lanthanum orthoferrite (LaFeO3) ceramics is reported. LaFeO3 nanoparticles were synthesized by using tartaric sol-gel route and annealed in air at different temperatures (500, 700 and 900 °C). The samples have been characterized by using thermal analysis (TA), BET surface area and porosity, Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Results of sensing tests indicate that LaFeO3 nanoparticles exhibit good response to oxygen at mild temperatures (300-450 °C). The effect of annealing temperature on gas sensing performance was investigated, demonstrating that LaFeO3 ceramics obtained after annealing at 500 °C display better characteristics with respect to others. The oxygen sensor developed shows also high stability in humid environment and excellent selectivity to oxygen over other interfering gases such as CO, NO2, CO2, H2 and ethanol.