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).