Magnesium-mediated nanocrystalline mosaics of calcite

Magnesium ions are widely found in calcium-based biominerals as an accessory component. In this report, the influence of magnesium ions on the crystal growth of CaCOa was investigated on the basis of the nanostructure. The morphology of calcite grown in a supersaturated solution was drastically changed from a regular rhombohedron into a spherical architecture consisting of nanocrystalline mosaics in the presence of a large number of magnesium ions. While magnesium ions were substituted for ca. 6% of calcium ions in the crystal lattice at a maximum, an excess amount of magnesium produced an amorphous phase leading to the nanostructure with modulation of the crystal growth of calcite.