The XRD, SEM and N2 adsorption measurements demonstrate
convincingly that both the chemical composition and the morphology
of the precipitates were influenced by (i) the calcium precursor,
(ii) the precipitation agent and (iii) the pH value at which precipitation
was performed. For example, using Ca(CH3COO)2 as the
calcium precursor and precipitating with Na2CO3 yielded CaCO3
mostly in the form of calcite, whereas precipitation with (NH4)2CO3
yielded CaCO3 mostly in the form of vaterite.