Monodisperse hematite cubes about 30nm in size have been prepared by aging a refluxing acidified aqueous solution of FeCl3 in an open vessel. The as grown nano cubes were determined to be single crystalline hematite in perfect cubic shapes using transmission electron microscope and electron diffraction. The nano cube is one of the equilibrium shapes of hematite, which is resumed to be formed by preferential growth in certain crystallographic directions through the species diffusion in the aqueous solutions.
Some self-assembly prototypes have been observed, such as the short range ordered buildup consisting of several brick-like hematite nano cubes and the nano box consisted of square plates of hematite nanocrystals. The drive force for the formation of the above assemblies is assumed to be the unique magnetic feature of the single crystalline hematite nano cubes.
The perfect shape and the self-assembly feature give a possibility to fabricate bulk ceramics orderly assembled using hematite nano cubes.