Dielectric properties of fluorine substituted hydroxyapatite: the effect of the substitution on configuration of hydroxide ion chains

N Horiuchi; J Endo; N Wada; K Nozaki; M Nakamura; A Nagai; K Katayama; K Yamashita

doi:10.1039/c5tb00944h

Dielectric properties of fluorine substituted hydroxyapatite: the effect of the substitution on configuration of hydroxide ion chains

J Mater Chem B. 2015 Sep 7;3(33):6790-6797. doi: 10.1039/c5tb00944h. Epub 2015 Jul 30.

Authors

N Horiuchi¹, J Endo, N Wada, K Nozaki, M Nakamura, A Nagai, K Katayama, K Yamashita

Affiliation

¹ Department of Inorganic Materials, Institute of Biomaterials & Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-0062, Japan. [email protected].

PMID: 32262472
DOI: 10.1039/c5tb00944h

Abstract

Hydroxyapatite (HAp) [Ca₅(PO₄)₃OH] is an extremely popular biomaterial. Moreover, HAp durability is well-known to be enhanced by fluoridation. We prepared fluoridated HAp (F-HAp; Ca₅(PO₄)₃(OH)_1-xF_x) ceramics by substituting F^- ions for OH^- ions of HAp. F-substitution dependence of dielectric properties in F-HAp was measured to detect the configuration change of OH^- ion chains. Dielectric relaxation of two kinds was observed. Each kind had a different relaxation time. Faster relaxation, which is associated with the reorientation motion of OH^- ions, was only observed at the low F-substitution range (0 ≤x < 0.35). The relaxation strength decreased as the F-substitution increased. It became zero at x = 0.35, suggesting that F-substitution induces hydrogen bonds. One F^- ion substituted for an OH^- ion forms two hydrogen bonds with the two neighboring OH^- ions and inhibits the motion of OH^- ions, which results in some kind of ordered configuration in F-HAp. The configuration might be an origin that enhances the durability of the F-HAp.