Preparation of iron nanoparticles by reduction of acicular β-FeOOH particles

Acicular β-FeOOH nanoparticles were prepared either by oxidation of ferrous chloride in a lamellar liquid crystal phase at 60°C, or by forced hydrolysis of ferric chloride at 80°C. The particles prepared in the liquid crystal phase were rod-shaped, with an average length of 85 nm and an aspect ratio of 12. Sodium borohydride reduction of these particles gave needle-shaped iron particles with lengths of about 80 nm. β-FeOOH particles prepared by forced hydrolysis of ferric chloride were ellipsoid-shaped with and average length of 70 nm and an aspect ratio of 7. Unfortunately, when these particles were reduced the iron particles did not maintain the shape and size. They were large chains of spheres or clusters of small particles with a distribution of sizes and shapes