Figure 1.

(a) X-ray diffraction (XRD) patterns of the CaP nanoparticles. The specific surface area (SSA), as determined by the nitrogen adsorption–desorption isotherms, along with the corresponding primary particle size, d_BET, are also shown. By varying FSP synthesis conditions either crystalline or amorphous particles are obtained. Main peaks are assigned to hydroxyapatite, Ca₅(PO₄)₃OH, whereas CaO is also observed. Transmission electron microscopy (TEM) images of as-prepared CaP_L (b) and CaP_S (c) samples. CaP_L particles are spherical with loosely agglomerated structure, while fused particles with sintered necks are clearly illustrated for CaP_S (Scale bar 50 nm).