title: Preparation and characterization of carbonated barium-calcium hydroxyapatite solid solutions.
abstract: Particles of carbonated barium-calcium hydroxyapatite solid solutions (BaCaHap) with different Ba/(Ba+Ca) (X(Ba)) atomic ratios were prepared by a wet method at 100 degrees C and characterized by various means. The crystal phases and structures of the products strongly depended on the composition of the starting solution, that is, the Ba/(Ba+Ca) atomic ratio ([X(Ba)]) and H3PO4 concentration ([H3PO4]) in the solution. BaCaHap with X(Ba)0.43 could be prepared at [X(Ba)]0.7 by changing [H3PO4], but could never be obtained at [X(Ba)]=0.8-0.95 regardless of [H3PO4]. The carbonated calcium hydroxyapatite particles prepared at [X(Ba)]=0 were fine and short rod-shaped particles (ca. 14x84 nm). With increasing [X(Ba)] from 0 to 0.8, the particles obtained became large spherical agglomerates. The carbonated barium hydroxyapatite particles formed at [X(Ba)]=1 were long rod-shaped agglomerates (ca. 0.2x2 microm) of fine primary particles. The amount of CO2 adsorbed irreversibly on a series of BaCaHaps showed a minimum at (Ba+Ca)/(P+C) atomic ratio of around 1.56, which agreed well with the minimum cation/P ratio obtained for the other hydroxyapatites, as already reported.
authors.affiliation: School of Chemistry, Osaka University of Education, 4-698-1 Asahigaoka, Kashiwara-shi, Osaka 582-8582, Japan.
authors.forename: Akemi
authors.initials: A
authors.lastname: Yasukawa
authors.forename: Eiichi
authors.initials: E
authors.lastname: Ueda
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Kandori
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Ishikawa
mesh_terms: D000327:Adsorption; D001464:Barium / Q000737:chemistry*; D002118:Calcium / Q000737:chemistry; D002245:Carbon Dioxide / Q000737:chemistry; D002254:Carbonates / Q000737:chemistry*; D003460:Crystallization; D017886:Durapatite / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry; D010316:Particle Size; D011312:Pressure; D012996:Solutions / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D002254:Carbonates; D012996:Solutions; D002245:Carbon Dioxide; D001464:Barium; C006685:barium carbonate; D017886:Durapatite; D009584:Nitrogen; D002118:Calcium