Hydroxyapatite (HAp) was prepared by the oxidative decomposition of calcium chelate (EDTA-Ca) using H2O2, and its morphology was investigated.
Morphological changes of HAp particles depended primarily on the amount of decomposition of EDTA-Ca. The morphology of HAp particles varied from a platy form to a japanese bladder cherry-like form (polyhedron crystal based on hexagon) and then to a chestnut-like form. When the additive rate of H2O2 was reduced, the morphology of HAp particles varied from a chestnut-like form to a japanese bladder cherry-like form and then to a platy form.
The composition of HAp with a japanese bladder cherry-like crystal form was calcium-deficient and carbonate-containing (Ca/P atomic ratio=1.52-1.56, CO3 content = approximately 5.5%). The HAp decomposed into a mixture of HAp and β-Ca3 (PO4) 2 by heating over 800°C.
