Preparation of acicular iron nanoparticles by the reduction of ferrous salt in the presence of tubular lecithin assemblies

Ferromagnetic alpha-Fe particles were prepared by reduction of Fe2+ in the presence of tubular lecithin assemblies found in lecithin/cyclohexane/water association colloids. The particles consisted of both large single- and multi-domain acicular rods, 0.25-5 mu m in length with a length to width ratio of at least 6:1, encapsulated in lecithin. The coercivity depended on the reaction medium and ranged from 7 to 131 Oe. The highest coercivity particles were obtained in the cyclohexane-rich region of the ternary phase diagram. (C) 1996 American Institute of Physics.