Colour centres in plasma-sprayed hydroxyapatite.
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.
Sharrock
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P
Université Paul Sabatier, Laboratoire de Chimie Inorganique, Toulouse, France.
Bonel
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G
D003116:Color; D004578:Electron Spin Resonance Spectroscopy; D006882:Hydroxyapatites / Q000737:chemistry*; D011208:Powders
D006882:Hydroxyapatites; D011208:Powders