A solid state synthesis of calcium manganite (CaMnO3) is described where equimolecular mixtures CaCO3:MnCO3 have been subjected to mechanical stress (high energy milling) so yielding CaCO3-MnCO3 solid solutions of nanometric particle size. TG measurements have shown that a link exists between milling time, the extent of non-stoichiometry and the milling-induced decomposition of MnCO3 to Mn3O4. A short (2 h) annealing at 850 ◦C performed on a sample mixture milled for 25 h leads to non-stoichiometric CaMnO3−x. No sure conclusion could be drawn for the stoichiometry of CaMnO3 obtained, under the same annealing conditions, from a mixture milled for longer time (150 h). No synthesis of CaMnO3 could be effected by long (48 h) annealing at 1200 ◦C of mixtures that had not been subjected to mechanical stress.

Solid state synthesis of CaMnO3 from CaCO3-MnCO3 mixtures by mechanical energy.

BERBENNI, VITTORIO;MILANESE, CHIARA;BRUNI, GIOVANNA;COFRANCESCO, PACIFICO;MARINI, AMEDEO
2006-01-01

Abstract

A solid state synthesis of calcium manganite (CaMnO3) is described where equimolecular mixtures CaCO3:MnCO3 have been subjected to mechanical stress (high energy milling) so yielding CaCO3-MnCO3 solid solutions of nanometric particle size. TG measurements have shown that a link exists between milling time, the extent of non-stoichiometry and the milling-induced decomposition of MnCO3 to Mn3O4. A short (2 h) annealing at 850 ◦C performed on a sample mixture milled for 25 h leads to non-stoichiometric CaMnO3−x. No sure conclusion could be drawn for the stoichiometry of CaMnO3 obtained, under the same annealing conditions, from a mixture milled for longer time (150 h). No synthesis of CaMnO3 could be effected by long (48 h) annealing at 1200 ◦C of mixtures that had not been subjected to mechanical stress.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11571/136396
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