Synthesis and physicochemical study of nanocrystalline magnesium-containing calcium hydroxylapatites and chitosan

The interaction in the CaCl(2)-MgCl(2)-(NH(4))(2)HPO(4)-NH(3)-H(2)O and CaCl(2)-MgCl(2)-(NH(4))(2)HPO(4)-(C(6)H(11)NO(4)) (n) -NH(3)-H(2)O systems at 25A degrees C has been investigated by the solubility (Tananaev's residual concentration) method and by pH measurements. Magnesium-containing calcium hydroxylapatites with the general formula Mg (x) Ca(10 - x) (PO(4))(6)(OH)(2) center dot nH(2)O (x = 0.05, 0.1, 0.2, 0.3; n = 6-7.3) and magnesium- and chitosan-containing calcium hydroxylapatites with the general formula Mg (x) Ca(10 - x) (PO(4))(6)(OH)(2) center dot y(C(6)H(11)NO(4)) center dot nH(2)O (x = 0.05, 0.1, 0.2, 0.3; y = 0.1, 0.3, 0.46; n = 6-8.3) have been isolated in the nanocrystalline state. The solids have been characterized by chemical and thermogravimetric analyses, X-ray diffraction, and IR spectroscopy.