Morphological transformation of hematite nanostructures during oxidation of iron.

Oxidation of metals usually results in the formation of an oxide nanostructure with poorly controlled growth morphologies. By employing a simple mechanical approach that uses sandblasting to modify the surface roughness of iron substrates, we demonstrate that the morphologies of hematite (α-Fe2O3) nanostructures varying from the growth of one-dimensional nanowires to two-dimensional nanoblades can be achieved during the thermal oxidation of iron. Electron microscopy studies show that the effect of surface sandblasting is to effectively modify the oxide nucleation locations that define the growth shapes. The optical properties of hematite nanowires and nanoblades are examined for the demonstration of the morphology-property correlations.