Roles of Metal Ions in the Formation of Hematite Particles from Forced Hydrolysis Reaction

Abstract

The roles of metal (Me) ions (Cu(II) and Cr(III)) in the morphologies and structures of hematite particles, produced from a forced hydrolysis reaction of FeCl3−HCl at various concentrations of metal ions ranging from 0 to 0.8 in the Me/(Fe + Me) atomic ratio (XMe), were investigated by separation of the reaction into two steps: precipitation of β-FeOOH and phase transformation from β-FeOOH to hematite. The metal ions inhibited the particle growth of β-FeOOH at a lower concentration region, while they promoted the particle growth at a higher concentration region with incorporation of these ions into the crystal lattice. The β-FeOOH particles produced with metal ions exhibited high specific surface areas and microporosities. It was suggested that the phase transformation from β-FeOOH to hematite is strongly affected by the metal ions incorporated into β-FeOOH particles but not by those adsorbed on the particle surface.