Synthesis and Properties of Hydroxyapatite Nanorods
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Hydroxyapatite (HA) nanopowders were synthesized at 70°C by a co-precipitation method using slaked lime and phosphoric acid solution at different pH values. Ammonia was used to adjust the pH of the aquatic media during synthesis. The prepared powders were dried overnight at 100°C and characterized for their phase composition using Fourier transform infrared spectroscopy (IR) and X-ray diffraction (XRD). Selected powder prepared at pH 11 was used for some investigations for its microstructural features as elucidated by transmission and scanning electron microscopy (TEM, SEM) and then sintered at different temperatures from 1000 to 1250°C to determine its bulk density and apparent porosity of sintered bodies. Results indicated that hydroxyapatite nanopowder was successfully prepared by co-precipitation. A dense microstructure with grain growth of the hydroxyapatite was detected when its sintering temperature was increased. The prepared hydroxyapatite was thermally stable upon heating up to 1100°C; whereas above 1100°C it was slightly dissociated into β-tricalcium phosphate (β-TCP) and CaO. At 1200°C the β-tricalcium phosphate (β-TCP) formed was converted to the α-tricalcium phosphate phase (α-TCP), which was again reconverted to hydroxyapatite and almost dissociated at 1250°C.
Keywordshydroxyapatite synthesis precipitation nanorods sintering
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