Direct hydrothermal synthesis of single-crystalline hematite nanorods assisted by 1,2-propanediamine.

Uniform alpha-Fe2O3 nanorods with high aspect ratios were synthesized in large scale by a simple and direct 1,2-propanediamine-assisted hydrothermal method. The resultant products were characterized by x-ray diffraction scanning electron microscopy, and transmission electron microscopy. The as-synthesized alpha- Fe2O3 nanorods were single crystalline and uniform, with an average aspect ratio greater than 10. The effects of various experimental parameters on the morphology of products, such as 1,2-propanediamine content, pH value, concentration of FeCl3 and reaction temperature, were studied. In the formation process of alpha- Fe2O3 nanorods, the 1,2-propanediamine not only provides OH(-) but also plays a role for retaining the rod-like morphology of hematite. The magnetic properties including Morin transition and coercivity of the samples with different synthesis conditions and aspect ratios were also investigated in detail.