HOLLANDITE CATHODES FOR LITHIUM ION BATTERIES: 1. SYNTHESIS AND CHARACTERIZATION OF THE MM'Mn7O16 COMPOUNDS (M= K, Ba; M' = Mg, Mn, Fe, Ni)
BaMMn7O16 (M = Mg, Mn, Fe, Ni) and AMn8O16 (A = Ba, K2) hollandite oxides were synthesized in air from metal carbonates and a mixture of simple oxides using the thermal decomposition in solid phase method at 850 C. The oxides BaMn8O16 and BaFeMn7O16 crystallized in the hollandite monoclinic phase, S...
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| Autores principales: | , , |
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| Lenguaje: | English |
| Publicado: |
Sociedad Chilena de Química
2001
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| Materias: | |
| Acceso en línea: | http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0366-16442001000200010 |
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| Sumario: | BaMMn7O16 (M = Mg, Mn, Fe, Ni) and AMn8O16 (A = Ba, K2) hollandite oxides were synthesized in air from metal carbonates and a mixture of simple oxides using the thermal decomposition in solid phase method at 850 C. The oxides BaMn8O16 and BaFeMn7O16 crystallized in the hollandite monoclinic phase, S.G. I2/m and S.G. P2(1)/n respectively, whereas K2Mn8O16 was tetragonal, S.G. I4/m. Two new phases are reported: BaMgMn7O16 and BaNiMn7O16 which crystallize in the hollandite monoclinic phase structure. The ionic distributions were proposed on the basis of several physicochemical analyses comporting XRD, GTA, magnetic susceptibility and oxidation power measurements. Barium and potassium manganites showed Mn3+ and Mn4+ in octahedral sites whereas BaMMn7O16 (M = Mg, Ni) exhibited Mn2+ and Mn4+ in sites B. On the other hand, iron-manganese hollandite, BaFeMn7O16, shows Fe3+ ions besides Mn3+ and Mn4+ cations |
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