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Theses

Etude chimique et structurale de l'ivoire d'éléphant moderne et ancien

Abstract : Elephant ivory is a biological material composed of collagen fibers (CF) at 30 wt. % and Mg-enriched carbonated hydroxyapatite particles at 70 wt. % (Mg-carb-HAP). It has a complex hierarchical structure from macro- down to nano-scale. The relationship between the macroscopic Schreger patterns observed on the surface of transverse sections of tuks and the 3D micro-morphology of ivory (tubular network and CF secondary orientations) has been established. Chemical (Ca, P, Mg, Sr) and structural markers (thickness and organization of particles Mg-carb-HAP) which control the formation of ivory have been determined. Early diagenesis in the marine environment was then studied by means of SEM, PIXE/RBS-EBS and SAXS analyses. Diagenetic mechanisms were identified, as ionic adsorptions from marine environment to the tusk surfaces, ionic substitutions between exogenous and endogenous ivory ions and increased crystallinity of Mg-carb-HAP. Different states of preservation were observed among three tusks coming from the same submarine archaeological site. Good macroscopic preservation states of the surface does not necessarily reflect good preservation states of the dentin at the molecular level. Finally, the former polychromy and gilding of ivories from Arslan Tash (Syria, 800 BC.) have been reconstructed by non-invasive FF-FX and PIXE/RBS-EBS analyses. Egyptian blue and green (Cu) with different shades (Pb), as well as red and orange (Fe) have been identified. The gilding technique consisted of applying a 2 µm thick gold leaf. Over time, these decorations altered ivory surfaces inducing, among others, the formation of Au nanoparticles derived from the weathering of the gold leafs.
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https://tel.archives-ouvertes.fr/tel-01132313
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2014PA066258.pdf
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  • HAL Id : tel-01132313, version 1

Citation

Marie Alberic. Etude chimique et structurale de l'ivoire d'éléphant moderne et ancien. Matériaux. Université Pierre et Marie Curie - Paris VI, 2014. Français. ⟨NNT : 2014PA066258⟩. ⟨tel-01132313⟩

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