Mechanochemical synthesis of hydroxyapatite from Ca(OH)2-P2O5 and CaO-Ca(OH)2-P2O5 mixtures

Dry grinding of Ca(OH)2-P2O5 and CaO-Ca(OH)2-P2O5 mixtures was conducted by a planetary ball mill to investigate the mechanochemical solid-phase reaction for the synthesis of hydroxyapatite (Ca10(PO4)6(OH)2, HAp). HAp was synthesized by grinding of the two sets of mixtures. The formation of HAp from the Ca(OH)2-P2O5 mixture was more advantageous than that from the CaO-Ca(OH)2-P2O5 one. This synthesis reaction from the former mixture was almost completed within 30 min of grinding. The presence and amount of H2O contained in the starting mixtures played a key role to promote the formation of HAp. Especially, in the former mixture, the prolonged grinding assisted the solid-phase reaction of the intermediate DCPD and Ca(OH)2 to produce HAp more effectively.