Synthesis, Characterization, and Magnetic Studies of Nonagglomerated Zerovalent Iron Particles. Unexpected Size Dependence of the Structure

Abstract

Sonolysis of a solution of Fe(CO)5 in anisol in the presence of poly(dimethylphenylene oxide) (PPO) leads to the formation of small nonagglomerated iron particles. HREM analysis shows that the size of the particles is centered around 30 Å with a medium dispersity. HREM analysis of the particles demonstrate that the smaller particles (≤25 Å) adopt the α-Fe (bcc) structure, whereas the larger ones (≥25 Å) adopt the γ-Fe (fcc) structure. Magnetic measurements confirm the presence of small superparamagnetic particles (α-Fe) and of mostly antiferromagnetic or paramagnetic particles (γ-Fe).