Synthesis and characterization of nano-crystalline calcium phosphates with EDTA-assisted hydrothermal method

This study aims to prepare the biologically important hydroxyapatite (HA), dicalcium phosphate dihydrate (DCPD) and dicalcium phosphate anhydrous (DCPA) phases in simple EDTA – assisted hydrothermal method. X-ray diffraction results showed that pure DCPD, DCPA and HA nano-crystals were obtained in the Ca–EDTA/PO4 solutions at 120 °C, 180 °C and 210 °C, respectively. Thermal gravimetric analysis of the DCPD precipitates revealed that phase transformations of DCPD to DCPA and DCPA to HA occurred at 139 °C and 195 °C, respectively, which resulted in the different Ca–P phases during hydrothermal synthesis at different temperature ranges.