Optical, Magnetic and Gas Sensing Properties of LaFeO3 Nanoparticles Synthesized by Different Chemical Methods

LaFeO3 nanoparticles were synthesized by different chemical procedures, i.e., microwave-thermal treatment method (MTTM), hydrothermal method (HTM) and sol–gel method (SGM), by using metal nitrates as La- and Fe-precursors. The synthesized nanoparticles were calcined at various temperature from 450°C to 1000°C. SEM analysis of samples synthesized by MTTM and SGM highlighted the formation of uniform spherical-like nanoparticles while those obtained by HTM were a combination of spherical particles and nanorods. X-ray diffraction patterns of nanocrystals confirmed that these nanoparticles are formed by crystalline LaFeO3 in the orthorhombic structure. The synthesized LaFeO3 were further investigated for analyzing their optical, magnetic and gas sensing behaviors. Band gap values for LaFeO3 by MTTM and HTM were in the range 2.07–2.41 eV and 1.57–1.94 eV, respectively, for the samples annealed at growing temperature, whereas vibrating sample magnetometer analysis demonstrated their weak ferromagnetic behavior. LaFeO3 synthesized by SGM showed interesting sensing properties for monitoring O2 and ethanol in ambient air.