The influence of small amounts of magnesium on the formation of calcium phosphates in moderately supersaturated solutions

The growth of calcium phosphates in moderately supersaturated solutions in the presence of small amounts of magnesium was studied at pH 8.50 and 26°C. Special attention was paid to the relative magnitude of the influence of magnesium on the different stages of the precipitation process. The experiments provide evidence that magnesium lowers the solubility of ACP and inhibits the growth and hydrolysis of OCP. At low magnesium concentrations the latter effect is most important. At higher concentrations and on practical time scales the first effect prevails, provided that the supersaturation is sufficiently high for the precipitation of ACP.