The carbonate-containing hydroxyapatites were prepared by heating the starting solutions in the Ca (NO3) 2- (NH4) 2HPO4- (NH2) 2CO-HNO3-H2O system with various additives, such as organic solvents and cations, in order to control the morphologies of the particles. The precipitates derived from the starting solution without additive were regarded as the carbonate-containing hydroxyapatite with Ca/P ratio of 1.70; they were composed of the fibrous particles with the long-axes sizes of-50 μm. When the six kinds of organic solvents, i.e, acetone, methanol, ethanol, ethylene grycol and glycerin were added to the starting solution, the precipitates consisted of the fiber- or whisker-like particles with various short- and long-axes sizes. These results showed that the particle size could be controlled by selecting the kinds of the organic solvents.
When various cations were added to the starting solution, the spherical carbonate-containing hydroxyapatite agglomerates formed from the starting solutions with Na+ and Mg2+ additions, whereas the fiber-like hydroxyapatite from the starting solutions with K+, Sr2+, Ba2+, Al3+ and Y3+ additions.
