Unexpected Mechanism of Zn2+ Insertion in Calcium Phosphate Bioceramics

S. Gomes; J.-M. Nedelec; Edouard Jallot; D. Sheptyakov; G. Renaudin

doi:10.1021/cm200537v

Unexpected Mechanism of Zn2+ Insertion in Calcium Phosphate Bioceramics

S. Gomes ¹ J.-M. Nedelec ¹ Edouard Jallot ² D. Sheptyakov ³ G. Renaudin ^{1, *}

* Corresponding author

1 LMI - Laboratoire des Matériaux Inorganiques

2 LPC - Laboratoire de Physique Corpusculaire [Clermont-Ferrand]

3 Laboratory for Neutron Scattering ETHZ & Paul Scherrer Institut

Abstract : 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.

Keywords : biomaterials zinc doping calcium phosphates Rietveld refinement Raman

Document type :

Journal articles

Chemistry of Materials, American Chemical Society, 2011, 23, pp.3072-3085. <10.1021/cm200537v>

Domain :

Life Sciences / Bioengineering / Biomaterials

Physics / Physics / Biological Physics

Chemical Sciences / Material chemistry

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Submitted on : Monday, July 11, 2011 - 3:43:18 PM
Last modification on : Tuesday, July 12, 2011 - 8:30:52 AM

Unexpected Mechanism of Zn2+ Insertion in Calcium Phosphate Bioceramics

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