The present investigation concerns synthesis of a ferromagnetic Mn2+-doped alpha-Fe2O3 following a co-precipitation method. Thus, an aqueous solution containing Fe3+ and Mn2+ ions in a molar ratio of 2:1 was precipitated as hydroxides and then dried at 100 degrees C. The product was characterized by XRD, TEM and TG-DTA. XRD and TEM analysis revealed that the 'as-prepared' material was largely 'amorphous' containing mixed-phase nanoparticles of alpha-FeOOH and MnFe2O4. The TG showed mass loss up to 250 degrees C while the DTA profile exhibited a broad exothermic peak in the temperature range similar to 300-800 degrees C, suggesting structural transformation. Additional phases were also synthesized by calcination of the initial product, at various temperatures, which were 200 degrees C, 450 degrees C, 600 degrees C and 750 degrees C. It was observed that in the temperature interval 600-750 degrees C, the material was transformed to Mn2+-doped alpha-Fe2O3 nanorods and nanoparticles having wide oblong shapes. The results were compared with pure alpha-Fe2O3 which was similarly synthesized without the presence of Mn2+. It was observed that unlike pure alpha-Fe2O3 which was antiferromagnetic, the Mn2+(alpha-Fe2O3) sample was ferromagnetic and showed much higher catalytic activity toward decomposition of hydrogen peroxide. The catalytic decomposition of H2O2 could be explained on the basis of Fenton and photo-Fenton effects.
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