Dielectric evaluation of fluorine substituted hydroxyapatite

Abstract

Fluorine-substituted hydroxyapatite (F-HAp) and stoichiometric hydroxyapatite (HAp) were prepared for investigation of their dielectric properties. Two kinds of dielectric relaxation were observed in HAp of each kind. One was attributed to the orientation of OH⁻. The relaxation strength was decreased strongly by the F-substitution. The activation energies (0.63 eV for HAp and 0.62 eV for F-HAp) of OH⁻ reorientation were independent of the F-substitution. The other relaxation was larger, where the activation energies were affected strongly by F-substitution. The F-substitution increased the activation energies from 0.73 to 0.88 eV. This increase of activation energies was related strongly to the increase of chemical stability by F-substitution in HAp.