An Iron Polyolate Complex as a Precursor for the Controlled Synthesis of Monodispersed Iron Oxide Colloids

A simple procedure that applies a hexanuclear iron−polyolate complex as an iron oxide precursor has been developed for the synthesis of colloidal iron oxide particles. The hydrolysis of this complex and the subsequent hydrothermal treatment of the intermediate product yield monodispersed hematite particles with a disclike shape. The outer diameter is about 1 μm and the thickness about 250 nm. The particles consist of small platelike crystallites that are almost perfectly aligned in the a−b plane. If acetyl acetone is added during the synthesis, similar but smaller disclike hematite particles (diameter ∼ 0.25−0.45 μm, thickness ∼ 80 nm) have been obtained. On the other hand, hydrazine as an additive leads to single crystals of hematite in the form of hexagonal platelets (diameter ∼ 0.6−1 μm, thickness ∼ 50 nm).