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Manganese ferrite synthesized from Mn(II) acetate + hematite freeze-dried powders

Freeze-drying was used to obtain a homogeneous fine powder containing (CH 3COO) 2Mn·2H 2O and α-Fe 2O 3 (molar ratio Fe:Mn = 3:1), which was thermally treated for 2 h in N 2 atmosphere, at 400 °C. This composite system was further annealed for 4 h in the same atmosphere, either at 700 °C or at 1000...

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Bibliographic Details
Published in:Materials chemistry and physics 2007-09, Vol.105 (1), p.92-98
Main Authors: Bellini, J.V., de Medeiros, S.N., Ponzoni, A.L.L., Longen, F.R., de Melo, M.A.C., Paesano, A.
Format: Article
Language:English
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Summary:Freeze-drying was used to obtain a homogeneous fine powder containing (CH 3COO) 2Mn·2H 2O and α-Fe 2O 3 (molar ratio Fe:Mn = 3:1), which was thermally treated for 2 h in N 2 atmosphere, at 400 °C. This composite system was further annealed for 4 h in the same atmosphere, either at 700 °C or at 1000 °C. The 700 °C annealed sample was thermally treated in air at 1200 °C and then rapidly quenched. The phase transformations that occurred in the freeze-dried and heat-treated powders were investigated by thermal analyses, X-ray diffractometry, scanning electron microscopy and Mössbauer spectroscopy. Results showed that MnO–α-Fe 2O 3–Fe 3O 4 compounds were obtained after the first heat-treatment. Samples subsequently annealed in N 2 atmosphere revealed the formation of Fe-rich manganese ferrites and manganowüstite phases. However, a single spinel phase was obtained for the sample that had been annealed and quenched in air.
ISSN:0254-0584
1879-3312
DOI:10.1016/j.matchemphys.2007.04.005