Formation and characterization of δ-FeOOH

Formation of δ-FeOOH was investigated by varying the experimental conditions of its synthesis. Samples were characterized by X-ray diffraction, transmission electron microscopy and Fourier transform infrared spectroscopy. Strong alkalinity of the mother liquor was an important factor for δ-FeOOH formation via the Fe (OH)2 precursor. A small amount of Fe3+ ions, present in the Fe (OH)2 precursor before the rapid oxidation of Fe2+ ions with H2O2 solution, was not critical for the formation of δ-FeOOH as a single phase. The best crystallinity of δ-FeOOH was obtained when the synthesis was performed in a completely inert atmosphere. Transmission electron microscopy showed that δ-FeOOH particles were present in the form of thin plates. The FTIR spectra of the samples prepared are discussed.