title: The formation mechanism of the beta-TCP phase in synthetic fluorohydroxyapatite with different fluorine contents.
abstract: Synthetic hydroxyapatite (HAP) and fluorohydroxyapatite (F(x)AP) products may form the beta-tricalcium phosphate (beta-TCP) phase in a calcination process. The beta-TCP phase has a greater tendency for degradation in vivo than HAP and F(x)AP. Hence, controlling the content of the beta-TCP phase in the apatite is a pivotal factor to affect their lifetime and stability in vivo. It is particularly important to explore the formation mechanism of the beta-TCP phase in synthetic apatite. In this work, F(x)AP products with a chemical composition of Ca(10)(PO(4))(6)(OH)(2-x)F(x) are synthesized, with x = 0, 0.4, 0.8, 1.2, 1.6 and 2.0, using a precipitation method and a calcination process. The effect of fluorine substitution for hydroxyl is investigated by using x-ray diffraction analysis, Fourier transform infrared spectroscopy, and thermogravimetry and differential thermal analysis. The results show that addition of fluorine forms F(x)AP that exhibits high thermal stability. The beta-TCP phase produced as a result of the structural refinement by heat treatment is gradually reduced and dramatically suppressed with the fluorine content.
authors.affiliation: School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001, People's Republic of China.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhao
authors.forename: Fuping
authors.initials: F
authors.lastname: Wang
authors.forename: Xiangqun
authors.initials: X
authors.lastname: Chen
authors.forename: Zhaodong
authors.initials: Z
authors.lastname: Wei
authors.forename: Dezhen
authors.initials: D
authors.lastname: Yu
authors.forename: Zhaohua
authors.initials: Z
authors.lastname: Jiang
mesh_terms: D018786:Bone Substitutes / Q000737:chemistry*; D002130:Calcium Phosphates / Q000737:chemistry*; D003198:Computer Simulation; D005461:Fluorine / Q000737:chemistry*; D006882:Hydroxyapatites / Q000737:chemistry*; D008422:Materials Testing; D008956:Models, Chemical; D044367:Phase Transition; D013696:Temperature; D044366:Transition Temperature
chemical_list: D018786:Bone Substitutes; D002130:Calcium Phosphates; D006882:Hydroxyapatites; C485817:beta-tricalcium phosphate; C116586:fluorohydroxyapatite; D005461:Fluorine