Ex situ Raman mapping study of mechanism of cordierite formation from stoichiometric oxide precursors

Ex situ Raman spectroscopy and Raman mapping showed that at temperatures below 1300 °C, magnesia reacted with either alumina or silica to form magnesium aluminate (spinel) or magnesium silicate. At 1300 °C or higher, the reaction between magnesium silicate and alumina, or spinel and silica, led to cordierite formation. Moreover, the presence of silica and spinel, and the disappearance of magnesium silicate at 1400 °C, indicated that cordierite formation was more favored by the reaction between alumina and magnesium silicate than by that between silica and spinel.