Production and characterization of submicron hematite (α-Fe₂O₃) particles by ultrasonic spray pyrolysis method

The ultrasonic spray pyrolysis (USP) method has been used to prepare submicron hematite (α-Fe₂O₃) particles using two different industrial pickling solutions of iron chloride (41 g/L FeCl₂ and 54 g/L FeCl₃) Particles were obtained by thermal decomposition of generated aerosols from precursor solutions using 1.7 MHz ultrasonic atomizer. Reaction temperature was set up at 800 °C and aerosol droplets were carried into the heated zone by 0.7 L/min air flow rate. X-Ray Diffraction (XRD) studies were used to determine the crystal structure and crystallite size of the particles. Results indicate that patterns correspond to hematite phase with rhombohedral crystal structure (space group: R3c). The crystallite sizes of particles prepared from FeCl₂ and FeCl₃ solutions that were calculated from Scherrer equation are 59 and 33 nm, respectively. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) investigations give detailed information about particle size, morphology and composition. SEM micrographs show that hematite nanoparticles aggregate and formed spherical secondary particles in submicron range.