Textures of tetradecahedron δ-FeOOH particles and their thermal decomposition products

δ-FeOOH particles have been prepared by oxidation of Fe(OH)2 with H2O2. The Fe(OH)2 precursors precipitated from a concentrated FeSO4 solution were aged at different temperatures from 40 to 110 °C. The δ-FeOOH particles obtained were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and N2 adsorption. The δ-FeOOH particles are tetradecahedra and the particle size increases from ca. 0.1 to 1 µm with increasing ageing temperature. The tetradecahedral δ-FeOOH particles are less crystalline. The N2 adsorption t-plots show the microporous structure of the δ-FeOOH particles obtained by ageing Fe(OH)2 at a higher temperature. The tetradecahedral α-Fe2O3 particles formed by outgassing these δ-FeOOH particles above 150 °C have micropores with sizes ranging from 0.8 to 2 nm.