title: Electrical characterization of hydroxyapatite-based bioceramics.
abstract: This paper studies the AC conductivity and permittivity of hydroxyapatite (HA)-based ceramics from 0.1 Hz-1 MHz at temperatures from room temperature to 1000 degrees C. HA-based ceramics were prepared either as dense ceramics or in porous form with interconnected porosity and were sintered in either air or water vapour. Samples were thermally cycled to examine the influence of water desorption on AC conductivity and permittivity. Surface-bound water was thought to contribute to conductivity for both dense and porous materials at temperatures below 200 degrees C. At temperatures below 700 degrees C the permittivity and AC conductivity of HA was also influenced by the degree of dehydration and thermal history. At higher temperatures (700-1000 degrees C), bulk ionic conduction was dominant and activation energies were of the order of approximately 2 eV, indicating that hydroxyl ions are responsible for conductivity.
authors.affiliation: Materials Research Centre, Department of Mechanical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, UK.
authors.forename: J P
authors.initials: JP
authors.lastname: Gittings
authors.forename: C R
authors.initials: CR
authors.lastname: Bowen
authors.forename: A C E
authors.initials: AC
authors.lastname: Dent
authors.forename: I G
authors.initials: IG
authors.lastname: Turner
authors.forename: F R
authors.initials: FR
authors.lastname: Baxter
authors.forename: J B
authors.initials: JB
authors.lastname: Chaudhuri
mesh_terms: D001672:Biocompatible Materials; D002516:Ceramics; D017886:Durapatite / Q000737:chemistry*; D004553:Electric Conductivity; D006358:Hot Temperature; D008855:Microscopy, Electron, Scanning; D014961:X-Ray Diffraction
chemical_list: D001672:Biocompatible Materials; D017886:Durapatite