High coercivity α-Fe2O3 nanoparticles prepared by continuous spray pyrolysis
Abstract
Surfactant free growth of α-Fe2O3 nanoparticles by continuous spray pyrolysis (CoSP) resulted in high coercivity (HC). X-ray diffraction (XRD), Raman spectroscopy, and Fourier transform infrared spectroscopy (FT-IR) confirmed the formation of pure α-phase of Fe2O3. Scanning electron microscopy (SEM) showed a dimpled-morphology in samples grown at ≥800 °C. XRD, SEM, Transmission electron microscopy (TEM) and temperature dependent magnetization data provided evidence of the presence of a sub-structure in the α-Fe2O3 particles. The Morin transition in the sample grown at 1000 °C is observed at 245 K with high coercivity (HC) ∼ 6 kOe at 300 K, which is among the highest reported in the literature. At 10 K, HC ∼ 10 kOe was observed for α-Fe2O3 grown at 600 °C which is also the highest coercivity reported in the literature. This remarkably high HC observed at low temperature correlates with the enhanced role of surface spins due to the surfactant free growth technique employed in the present work.