Hydroxyapatite synthesised from nanosized calcium carbonate via hydrothermal method

Hydroxyapatite (HAp) was synthesised using a hydrothermal method. Nanosized CaCO ₃ was used as the calcium source, while (NH ₄) ₂HPO ₄ was used as the phosphorous source. Well crystallised HAp and a small amount of b-tricalcium phosphate (β-TCP) were obtained after the hydrothermal reaction. Fourier transform infrared spectra show that under conditions of pH 6 and 250°C, the functional groups of OH ^- and PO4 ^3- were stronger than those under pH 10. This suggests that the powder synthesised at pH 6 has more HAp phase than that at pH 10. Scanning and transmission electron microscope images show that HAp exhibits a rod-like shape at pH 6 and 250°C. After hydrothermal reaction at pH 6 and 250°C, most products are HAp with a small amount of β-TCP synthesised as byproduct and some residual CaCO ₃.