Chemical Precipitation Synthesis and Magnetic Properties of Hematite Nanorods
One-dimensional (1D) hematite (α-Fe2O3) nanorods have been successfully prepared using a chemical precipitation method. The sample was characterized by using a variety of techniques, such as X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). The results showed that the nanorods obtained were monocrystalline, with an average diameter of about 60nm and a length of up to 800nm. In the preparation of α-Fe2O3, the length of α-Fe2O3 seemed to increase with the addition of polyethylene glycol (PEG), and the diameter seemed to decrease with the addition of Zn2+. Nanorods of α-Fe2O3 with a smaller diameter and superior slenderness ratio were prepared by adding both PEG and Zn2+. A possible growth mechanism effect of PEG and Zn2+ upon the morphology of α-Fe2O3 was as follows: α-FeOOH grew in a one-dimensioned orientation upon the surface of a polyethylene glycol template. In the meantime, the Fe3+ position in the α-FeOOH crystal was substituted by Zn2+; resulting in point defects in α-FeOOH crystal due to the radius discrepancy between Zn2+ and Fe3+. The growth-step energy was then reduced as a result of the point defects in the α-FeOOH crystal. The results of magnetic measurements of the hematite nanorods revealed a weak ferromagnetic property which might be related to the shape anisotropy.
David J. Fisher
Q. L. Li et al., "Chemical Precipitation Synthesis and Magnetic Properties of Hematite Nanorods", Defect and Diffusion Forum, Vol. 293, pp. 77-82, 2009