Pseudomorphism and size stabilization of hematite particles in the organic phase synthesis

In this paper, we suggest the synthetic routes to prepare octahedrally crystallized hematite particles. One of these routes allows stabilizing pseudomorphic nanoparticles. Calcination of iron (III) oleate at 300 ​°C in air gives triangular shaped magnetite particles. At higher temperatures (400–500 ​°C), the octahedrons, about 1 μm in size, with predominant hematite phase are obtained. Calcination of the same precursor in the presence of polymeric beads results in a decrease of particle size up to 20 ​nm while preserving the magnetic phase admixture. To achieve effective stabilization, swelling of polystyrene beads during the iron (III) oleate impregnation is required.