Abstract
In this work, mono-disperse hematite iron oxide (alpha-Fe2O3) nanoparticles with continuously tunable sizes from 2 to 11 nm by using Sb doping in alpha-Fe2O3 were synthesized by a sonication method at room temperature followed by calcination. By varying the concentration of the Sb, precise control on the size of the alpha-Fe2O3 nanoparticles could be established. The X-ray diffraction (XRD), and high resolution transmission electron microscopy (HR-TEM) studies confirmed that the prepared nanoparticles were hematite with high crystallinity. The optical measurements showed that the band gap of the Sb-doped alpha-Fe2O3 nanoparticles increased with Sb doping. Transmission electron microscopy (TEM) results showed that the alpha-Fe2O3 nanoparticles appeared as spherical dots, and the size decreased from 11 to 2 nm with Sb doping. Magnetic studies revealed that all the Sb doped samples were superparamagnetic at 300 K, and the increase in Sb doping can controllably decreased the blocking temperature from 248 K for pure alpha-Fe2O3 nanoparticles to 209 K for 5% Sb doped, respectively. The presented method might be useful for controlling the diverse size of crystalline inorganic materials for a variety of applications.