Formation of porous α-Fe2O3 microstructure by thermal decomposition of Fe(IO3)3

Formation of porous α-Fe2O3 microstructure by thermal decomposition of Fe(IO3)3 was monitored using 57Fe Mössbauer spectroscopy, FT-IR spectroscopy and field emission scanning electron microscopy. Spherical Fe(IO3)3 particles were built of close-packed hexagonal rods. Both, Fe(IO3)3 as prepared and Fe(IO3)3 thermally treated at 300 °C showed a single line in the corresponding Mössbauer spectra recorded at room temperature. At 350 °C and higher temperatures, the microporous network appeared. The DTA curve of Fe(IO3)3 showed a very strong and broad endothermic peak between 440 and 535 °C, centered at 515 °C due to complete thermal decomposition of Fe(IO3)3. Upon heating at 800 °C recrystallization of microporous α-Fe2O3 network occurred, whereas, the porous microstructure almost disappeared upon heating at 900 °C, and close-packed hexagonal α-Fe2O3 subunits were formed. The spherical shape of the particles was preserved from room temperature to 900 °C.