Manganese ferrite synthesized from Mn(II) acetate+hematite freeze-dried powders
| Autor: | M.A.C. de Melo, F.R. Longen, S.N. de Medeiros, A.L.L. Ponzoni, Andrea Paesano, Jusmar V. Bellini |
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| Rok vydání: | 2007 |
| Předmět: |
Materials science
Scanning electron microscope Composite number Spinel chemistry.chemical_element Manganese engineering.material Hematite Condensed Matter Physics Crystallography chemistry Phase (matter) visual_art Mössbauer spectroscopy engineering visual_art.visual_art_medium General Materials Science Thermal analysis Nuclear chemistry |
| Zdroj: | Materials Chemistry and Physics. 105:92-98 |
| ISSN: | 0254-0584 |
| DOI: | 10.1016/j.matchemphys.2007.04.005 |
| Popis: | Freeze-drying was used to obtain a homogeneous fine powder containing (CH3COO)2Mn·2H2O and α-Fe2O3 (molar ratio Fe:Mn = 3:1), which was thermally treated for 2 h in N2 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 Mossbauer spectroscopy. Results showed that MnO–α-Fe2O3–Fe3O4 compounds were obtained after the first heat-treatment. Samples subsequently annealed in N2 atmosphere revealed the formation of Fe-rich manganese ferrites and manganowustite phases. However, a single spinel phase was obtained for the sample that had been annealed and quenched in air. |
| Databáze: | OpenAIRE |
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