1992 Volume 65 Issue 4 Pages 238-243
Hydroxyapatite has been prepared by the hydrolysis of calcium hydrogenphosphate. We have tried to increase the Ca/P molar ratio in hydroxyapatite and to raise the yield by adding calcium hydroxide particles having high dissolution rate, which was prepared from active calcium oxide and hot water to the reaction system. It was revealed that a lower addition rate of calcium hydrogenphosphate to the reaction system, and higher reaction temperature and dissolution rate of calcium hydroxide tended to increase the Ca/P molar ratio. The highest value of the Ca/P molar ratio of the solid product obtained in this study was only 1.44. This value was too small in comparison with the theoretical value of Ca/P molar ratio of stoichiometric hydroxyapatite. The reason for the disagreement was discussed. The solid product (Ca/P molar ratio=1. 44) obtained in the heterogeneous reaction changed to β-calcium phosphate particles by heating at 1000°C for 180 min.
