Rapid synthesis of calcium deficient hydroxyapatite nanoparticles by microwave irradiation

Calcium deficient hydroxyapatite (CDHA, Ca10-x (HPO 4)x (PO4)6-x (OH)2-x) has attracted many researchers as natural biocrystals of bone mineral has CDHA structure with Ca/P ratio of about 1.5, which is chemically and compositionally similar to beta tricalcium phosphate (â-TCP) and structurally similar to stoichiometric hydroxyapatite (Ca/P = 1.67). Rapid synthesis of CDHA was done by co-precipitation process of calcium nitrate tetra-hydrate and phosphoric acid and subsequently subjecting the rinsed precipitate to microwave irradiation in a domestic microwave oven. Transmission electron microscopy analysis shows needle like morphology of CDHA having length 16-39 nm and width 7-16 nm. The synthesized CDHA shows characteristic HPO42- vibration band at 875 cm-1 in Fourier transform infrared (FT-IR) spectra. The additional confirmation of CDHA by its thermal decomposition to â-TCP was also studied using XRD and FT-IR. The CDHA was stable up to 600°C and transformed to â-TCP at around 650°C.