Fig. 5: Temporal evolution of minerals formed in the presence of inorganic phosphate with Ca/P = 3.

SEM images show the minerals formed after 1 day (a–a1), 3 days (b–b1), 6 days (c–c1), and 9 days (d–d1). The schematic representation of apatite evolution towards calcite with eroded surfaces is showed in (e). FTIR spectra of minerals formed after different reaction time (f).