title: Colour centres in plasma-sprayed hydroxyapatite.
abstract: Very pure hydroxyapatite is diamagnetic and shows no electron paramagnetic resonance (EPR) spectrum. Plasma-sprayed coatings made with such a pure hydroxyapatite contain paramagnetic point-defects. Irradiated deposits show a strong EPR absorption assigned to an O2- anion adjacent to a calcium vacancy, with anisotropic parameters, g1 = 2.004, g2 = 2.013 and g3 = 2.038. The EPR spectra and colour fade away following thermal annealing. These features are discussed in terms of point-defects in the hydroxyapatite crystal structure.
authors.affiliation: Université Paul Sabatier, Laboratoire de Chimie Inorganique, Toulouse, France.
authors.forename: P
authors.initials: P
authors.lastname: Sharrock
authors.forename: G
authors.initials: G
authors.lastname: Bonel
mesh_terms: D003116:Color; D004578:Electron Spin Resonance Spectroscopy; D006882:Hydroxyapatites / Q000737:chemistry*; D011208:Powders
chemical_list: D006882:Hydroxyapatites; D011208:Powders