DIFFERENCE OF CARBONATE IONS INCORPORATED INTO A CATTLE BONE-ORIGINATED AND A CHEMICALLY SYNTHESIZED HYDROXYAPATITES

Carbonate ions incorporated into two hydroxyapatites of different orig ins cattle bone-originated (r-HAp) and chemically-synthesized (s-HAp), were compared with emphasis placed on the morphology of these two hyd roxyapatites. In r-HAp pretreated at 1073 Ii, a Pod-substituted and an OH-substituted carbonate ions were observed. On the other hand, s-HAp had only the PO4-subsituted carbonate ion. This difference suggested that r-HAp had a more calcium-deficient structure and a larger density of OH-vacancies to compensate the decrease of Ca2+, which moves the O H-substituted carbonate ion forming more easily. This was in agreement with the difference of morphology in the two HAp's observed by held e mission-scanning electron microscopy: the r-HAp was constituted by ass emblies of relatively round particles of 50-100 nm in diameter, while the s-HAp was bar-shaped particles of 100-300 nm in length, meaning th at the r-HAp does not grow so easily as the s-HAp along crystallograph ic c-axis.