Rapid synthesis of monodispersed α-Fe₂O₃ nanoparticles from Fe(NO₃)₃ solution by microwave irradiation

Monodispersed α-Fe₂O₃ nanoparticles were prepared at 100°, 120°, and 140°C using 0.02, 0.05, and 0.1 M-Fe(NO₃)₃-9H₂O solutions by microwave-hydrothermal (M-H) and conventional-hydrothermal(C-H) reactions. Compared to the formation of monodispersed α-Fe₂O₃ particles using the C-H reaction, the M-H reaction led to increased rate of formation by 3 times at 120°C and 5 times at 140°C from 0.1 M-Fe(NO ₃)₃ solutions. α-Fe₂O₃ nanoparticles of 23-25 nm in diameter were obtained from 0.02 M solution at 100°C after treatment for 4 h by applying microwaves, which led to the formation of smaller sized particles with a narrow particle size distribution. The coagulation of nano-sized single crystals of 5 to 6 nm in diameter was enhanced by increasing the concentration of Fe(NO₃)₃ solutions.