Low-temperature synthesis and nanomagnetism of large-area α-Fe ₂O₃ nanobelts

Large-area one dimensional (1D) α-Fe₂O₃ nanostructures were grown on iron substrates by catalyst-free thermal oxidation process at low temperatures in air. The structure characterization revealed that the nanostructures are single crystalline α-Fe₂O₃. Two kinds of α-Fe₂O₃ nanostructures, nanobelts and nanoflakes, were obtained due to the different growth temperature range. A surface diffusion mechanism is proposed to account for the nanobelts and nanoflakes growth. The Morin temperature T_M of pure 1D α-Fe₂O₃ nanostructures is 121 K, which is far below their bulk counterparts. The coercive field depends on temperature, and takes values 471 Oe at 5 K and about 260 Oe when the temperature is greater than T_M, respectively.