[Specific physicochemical properties of apatites. 10. Fe-containing fluoridated apatites]

Fe-containing hydroxyapatites and fluoridated hydroxyapatites were synthesized at 80 degrees C and pH 7.4. Fe-containing hydroxyapatites became poorly crystallized with the increase of Fe2+ ions in the solution and a- and c-axis dimensions seemed to decrease slightly. The apparent solubility of Fe-containing hydroxyapatites decreased greatly with the increase of iron content in spite of the decrease in crystallinity. Fe-containing fluoridated apatites were less well crystallized than Fe-free fluoridated apatites. The Fe2+ uptake of fluoridated apatites was independent of fluoride concentration in the solution. a-Axis dimensions of Fe-containing fluoridated apatites decreased with the degree of fluoridation in addition to the decrease related to the substitution of Fe2+ ions. The apparent solubility of Fe-containing fluoridated apatites decreased more than that of Fe-free fluoridated apatites especially at a low fluoride content.