The synthesis mechanism of Ca3Al2O6 from soft mechanochemically activated precursors studied by time-resolved neutron diffraction up to 1000 C
نویسندگان
چکیده
The reaction pathway for the Ca3Al2O6 formation up to 1300 C; from mechanochemically treated mixtures of amorphous aluminum hydroxide and CaCO3; was studied in situ by differential thermal analysis, constant heating rate dilatometry and timeresolved neutron powder diffraction. The experiment was carried out, in an open system, on a sample with the nominal Ca3Al2O6 stoichiometry. The results obtained by neutron diffractometry and thermal analysis were in good agreement with the data obtained by scanning electron microscopy and X-ray diffraction on heat-treated and-quenched samples. The synthesis path implied the formation of cryptocrystalline Al2O3; crystalline CaO, CaAl2O4 and Ca12Al14O33 as transitory phases. Finally the nucleation and growth of the single phase Ca3Al2O6 took place at 1300 C and exhibited porous structure due to CO2 and H2O release. r 2003 Elsevier Inc. All rights reserved.
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