Shape-controlled synthesis of hydroxyapatite in organic media

We have examined the effect of organic solvent on the microstructures of hydroxyapatite (HAp) formed by hydrolysis of alpha -tricalcium phosphate (alpha -TCP) in heterogeneous solvent system (water-hydrophobic organic solvent). The shape of HAp was like ultrafine whisker (length : about 1 similar to 4 mu m) and its size depended on the used organic solvent. As a simple hybridization, incorporation of fluoride anion (F-) into HAp was attempted in similar system to obtain fluoridated apatite [Ca-10(PO4)(6)(OH)(2-x) F-x]. The formation rate was strongly affected by the concentration of F- and reaction temperature. Although the product in water (in the absence of organic solvent) consists of fine particles less than 1 mu m, the product prepared in the heterogeneous solvent system was mixture of ultrafine particles (similar to 0.1 mu m) and needlelike particles (length : about 1 similar to 4 mu m, width : similar to 0.5 mu m). The microstructures of HAp and FHAp were controlled by hydrophobicity of organic solvent.