Template synthesis and characterization of highly ordered lamellar hydroxyapatite

Surfactant template synthesis attracts great attention in the fields of biomaterials and functional materials. In this study, highly ordered lamellar hydroxyapatite (Lalpha-HA) powder was synthesized by a surfactant templating method in water-ethanol. Ca(NO3)2 and (NH4)2HPO4 were used as calcium and phosphorus sources, respectively. Sodium dodecyl sulphonate (SDS, C12H25SO3Na) acted as the template. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses showed that HA is the only crystal phase in Lalpha-HA. Transmission electron microscope (TEM) observation further proved this regular lamellar structure detected by XRD. The repeat periodicity of the structure is about 3.6nm observed by TEM, which is in well accordance with the XRD data (3.16nm). The selected area electron diffraction (SAED) results indicated that Lalpha-HA was a polycrystalline structure. The formation of Lalpha-HA could be explained by a surfactant template.