Specimens for these experiments wer

Specimens for these experiments were prepared from nanovaterite powder obtained from the precipitation of calcium chloride and sodium carbonate in water, as previously reported. [22] The precipitation reaction results in spherical agglomerates in the size range 8-15um, which are formed by interconnected nanoparticles with size on the order of 50 nm (Fig. 2). X-Ray diffraction of the precipitated powder confirms the formation of vaterite crystals. The presence of a calcite peak in the X-Ray diffraction spectrum is associated with the formation of a few large calcite particles that are readily visible by SEM imaging.[22]