title: Heterogeneous Mg-containing hydroxyapatites.
abstract: Two different Mg-containing hydroxyapatites, H-MgAp and Mg-HAp, were synthesized at 80 degrees C and pH 7.4. For H-MgAp, the calcium solution was supplied in the first half of the synthesis period and the calcium solution containing magnesium was supplied in the second half. For Mg-HAp, the order of supply was reversed. The X-ray diffraction patterns of H-MgAp and Mg-HAp differed slightly from each other. The (002) reflection of both patterns shifted towards a higher angle. The chemical compositions, especially the Mg contents, of the two apatites were almost the same as each other; and the Mg contents were half of that of homogeneous MgHAp synthesized with continuous supply of Mg at the same concentration. However, their crystal shapes were quite different, with H-MgAp appearing plate-like and Mg-HAp needlelike. In a solubility experiment, Mg-HAp was more soluble than H-MgAp. These results suggest that two different heterogeneous Mg-containing hydroxyapatites may be formed: hydroxyapatite covered with Mg-containing hydroxyapatite, and Mg-containing hydroxyapatite covered with hydroxyapatite.
authors.affiliation: Department of Dental Technology, Osaka University, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Okazaki
authors.forename: J
authors.initials: J
authors.lastname: Takahashi
mesh_terms: D018360:Crystallography, X-Ray; D004577:Electron Probe Microanalysis; D006882:Hydroxyapatites / Q000138:chemical synthesis / Q000737:chemistry*; D008274:Magnesium / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D012995:Solubility
chemical_list: D006882:Hydroxyapatites; D008274:Magnesium