Objective: This study investigated effects of heat treatment on the crystallinity and phase composition of hydroxyapatites (HAs) of different heat treatment. Methods: HA powder was synthesized by the chemical precipitation method based on the reaction between the phosphorous acid and calcium hydroxide. Synthesized HA was divided into three groups for which each group was then given heat treatment at 100°C, 900°C, or 1300ºC. Phase identification, analyses and the crystallinity of the synthesized HAs were determined using the X-ray diffraction coupled with the Rietveld refinement. Results: The synthesized HAs with each heat treatment were identified as HA phase containing hexagonal structure. Those treated at 100°C or 900°C revealed with crystallinity of 48% and 68%, respectively, with no additional phase; whereas, those treated at 1300°C produced a crystallinity of 72% and contained dicalcium and tricalcium phosphates. Conclusion: The synthesized HAs treated at 100°C, 900°C, or 1300°C were HA phase with hexagonal structure. The variable crystallinity of the synthesized HAs yielded from different heat treatment temperature correspondingly determines different phase composition.
- Heat treatment
- Secondary phase