PREPARATION OF NANO-NEEDLE HEMATITE PARTICLES IN SOLUTION

摘要

Uniform nano-needle hematite particles were prepared by forced hydrolysis, namely, by reflux of Fe(NO_3)_3 solution in the presence of organic chelating agent l-hydroxyethy l-l, l-diphosphonic acid (HEDP) and HNO_3. Nano-nee dle hematite particles with a length of 90 - l00 nm and axial ratio of 9 - l2 were obtained. The effect of the concentration of HEDP and HNO_3 on the mor- phology of the mematite particles was investigated by transmission electron microscopy (TEM). From the morphology of the particles extracted at differ- ent stages of hydrolysis, we think the amount of positive charges on the primary particle surface is crucial for the formation of nano-needle particles.