Phase Transformation of Magnesium Amorphous Calcium Carbonate (Mg-ACC) in a Binary Solution of Ethanol and Water

In this article, we report that the phase transformation of magnesium amorphous calcium carbonate (Mg-ACC) can be easily realized in an ethanol/water mixed solution free from organic additives under mild conditions, and the phase transformation can be nicely captured by the choice of a suitable concentration of Mg-ACC, the volume ratio of ethanol to water as well as the reaction temperature. Moreover, a complex self-assembly process for the production of aragonite aggregate with ellipsoid shape in this binary solvent has been proposed. These results demonstrate that controlled phase transition from Mg-ACC can be easily achieved by using a binary reaction media. This study may provide some useful clues for understanding the mineralization process of CaCO3 in nature and implies that this method could be scaled up for industrial production of CaCO3 with different polymorphs.