Surfactant-assisted synthesis of hydroxyapatite particles

Various morphologies of nano hydroxyapatite particles (HAP; Ca10(PO4)(OH)2) were synthesized through the hydrothermal method using CTAB as a template. TEM micrographs reveal the hydroxyapatite particles ranged from spheroid to long fibers. The obtained smallest average diameter of spheroidal particles, ∼27 nm, were achieved at 90 °C, pH = 13 for 20 h. The biggest long fibers, more than 1125 nm and ca. 60 nm in width, were obtained at 150 °C, pH = 9 for 20 h. The morphology of the obtained particles presented a certain rule with the temperature at different pH values. A probable mechanism involves the interaction of the tetrahedral CTAB cation structure, the tetrahedral PO43− structure and the OH− ions at different pH values. The results show that the nano hydroxyapatite particles can be tailored through the control of the process temperature, the reaction time, the concentration of CTAB and the pH value of the solution.