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Unexpected Mechanism of Zn2+ Insertion in Calcium Phosphate Bioceramics
Gomes S., Nedelec J.-M., Jallot E., Sheptyakov D., Renaudin G.
Chemistry of Materials 23 (2011) 3072-3085 - http://hal.in2p3.fr/in2p3-00607861
Sciences du Vivant/Ingénierie biomédicale/Biomatériaux
Unexpected Mechanism of Zn2+ Insertion in Calcium Phosphate Bioceramics
S. Gomes1, J.-M. Nedelec1, E. Jallot2, D. Sheptyakov3, G. Renaudin ()1
1 :  LMI - Laboratoire des Matériaux Inorganiques
CNRS : UMR6002 – Université Blaise Pascal - Clermont-Ferrand II – Clermont Université – Ecole Nationale Supérieure de Chimie de Clermont-Ferrand
24 Avenue des Landais 63177 AUBIERE CEDEX
2 :  LPC-CLERMONT - Laboratoire de Physique Corpusculaire de Clermont-Ferrand
CNRS : UMR6533 – IN2P3 – Université Blaise Pascal - Clermont-Ferrand II
Campus des Cézeaux 24, avenue des Landais BP 80026 63171 Aubière Cedex
3 :  Laboratory for Neutron Scattering ETHZ & Paul Scherrer Institut
Laboratory for Neutron Scattering ETHZ & Paul Scherrer Institut
CH-5232 Villigen PSI, Switzerland
Rietveld analysis on X-ray powder diffraction patterns recorded from Zn-doped, Zn/Sr, and Zn/Mg codoped biphasic calcium phosphate (BCP) samples has been used to locate Zn2+ cations in both hydroxyapatite (HAp) and β-tricalcium phosphate (β-TCP) phases heat-treated at 1100 °C. Zn atoms occupy interstitial sites in HAp (Wyckoff site 2b), leading to an insertion solid solution of general composition Ca10Znx(PO4)6O2x(OH)2-2x. Replacement of hydroxyl by O2- anions with formation of linear O-Zn-O entities should be considered to preserve the electroneutrality of the material. Contrary to HAp case, Zn atoms substitute calcium atoms in β-TCP leading to a substitution solid solution of general composition Ca3-xZnx(PO4)2. Micro-Raman spectroscopy and neutron diffraction have confirmed these insertion/substitution mechanisms. The different mechanisms of zinc incorporation should be considered to stabilize the desired calcium phosphate phase which are managed by the Ca/P and (Ca+Zn)/P ratios. Furthermore, discussion of biological properties of Zn-doped calcium phosphate ceramics should take into account the true insertion mechanism as critically discussed here.

Articles dans des revues avec comité de lecture
Chemistry of Materials (Chem. Mater.)
Publisher American Chemical Society
ISSN 0897-4756 (eISSN : 1520-5002)
Copyright © 2011 American Chemical Society

biomaterials – zinc doping – calcium phosphates – Rietveld refinement – Raman