EFFECT OF PREPARATION CONDITIONS ON MICROSTRUCTURE OF NANO-HYDROXYAPATITE SYNTHESIZED BY CHEMICAL PRECIPITATION METHOD

Nano-hydroxyapatite (n-HA) was synthesized through precipitation method with Ca (NO3)2•4H2O and (NH4)2HPO4. The effects of reaction temperature, pH and calcination on the microstructure and the growth of n-HA crystals were studied by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. At the same time, the growth mechanism was discussed. The results revealed that the crystals grew more complete and the particle size tended to increase with increasing temperature. The pH of the systems has a greater impact on the growth of n-HA crystals. With the increase of the pH value, the HA crystallinity and crystal grain size decrease significantly. Crystal size become the bigger after calcination, high crystallinity and crystal clear Spherical-like n-HA crystals with about 70-80 nm average size, equal particle size, and good dispersity can be obtained under the condition of 40°C, pH=10 for 4 hours. EDS analysis results confirmed that the average Ca/P ratio of the synthesized HA was about 1.85 by precipitation method, belonging to the rich calcium type of HA.