Formation of α-Fe2O3 nanoflakes by heating Fe in air

Flake-shaped hematite (α-Fe2O3) nanostructure has been successfully fabricated by using a hot-plate to directly heat Fe foil or Fe-coated substrates in air at 300oC. After heating, the surface of the samples was found to be populated with α-Fe2O3 nanoflakes. Such growth of α-Fe2O3 nanoflakes was very substrate-friendly. They can be formed on blank Si wafer, patterened Si, AFM tips, silica sphere, quartz, glass slide, Al foil and electrochemically etched W tip. The formation process and the final products were investigated by glancing angle x-ray diffraction (GAXRD), micro-Raman, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results indicate the final products are single crystalline α-Fe2O3 nanoflakes vertically standing on the Fe3O4 film that acts as the precursor for growth of α-Fe2O3. The α-Fe2O3 nanoflakes formed by this method show very sharp tip with the tip radii as small as several nanometers and large surface to volume ratio. Such nanoflakes may be potentially useful as novel candidates for future electron field emission and gas senor devices. Furthermore, it is believed that this simple and substrates-friendly method is useful in extending the applications of α-Fe2O3 nanostructures.