Fig. 4

Scanning electron microscope images of calcium carbonate crystals. a Rhombohedral calcite crystals formed in the presence of CA, b spherical vaterite crystals formed in the absence of CA (Bose and Satyanarayana 2017)
Scanning electron microscope images of calcium carbonate crystals. a Rhombohedral calcite crystals formed in the presence of CA, b spherical vaterite crystals formed in the absence of CA (Bose and Satyanarayana 2017)