Journal of Nano Research Vol. 8

Abstract: The ancient mirror amalgam is a two-phase system: crystals of tin-mercury compounds surrounded by a mercury-rich liquid phase. Corrosion of the amalgam mirrors produces tin dioxide and tin monoxide and releases liquid mercury from the solid phase. The objectives of this study were to characterise the formation of the SnO2 nanometric particles in the alteration processes of ancient amalgam mirrors. Using grazing incidence X-ray diffraction, a depth profile analysis of the sample was performed. The morphology of the amalgam layer was studied by scanning electron microscopy (SEM), and transmission electron microscopy (TEM) was used to study the size and morphology of the particles. Elemental analysis of the amalgam was done by energy dispersive X-ray spectrometry (EDX). The SnO2 phase was straightforwardly identified by XRD using different incidence angles. The average crystalline size of the nanoparticles was evaluated using the Scherrer formula and was estimated in the range of 4 to 5 nm, which was in good agreement with the size estimated by TEM. The electron diffraction pattern of the nanoparticles could be indexed to the cassiterite (SnO2) structure, which is the most typical and stable corrosion product of tin.

Abstract: The use of metal nanoparticles dispersed in an optically clear matrix by potters and glassmakers from the Bronze Age up to the present time is reviewed from the solid state chemistry and material science point of view. The nature of metal (gold, silver or copper), the importance of some other elements (Fe, Sn, Sb, Bi) added to control metal reduction in the glass in relation to the firing atmosphere (combined reducing oxidizing sequences, role of hydrogen and water) are considered in the light of ancient Treatises and recent analyses using advanced techniques (FIB- TEM, EXAFS,…) and classical methods (optical microscopy, UV-visible absorption). The different types of colour production, by absorption/reflection (red, yellow) or diffraction (iridescence) and the relationship between nanostructure (metal particle dispersion, layer stacking) and lustre colour are discussed. The very specific interaction between light and the metal nanoparticle makes Raman scattering a very useful "bottom up" technique to study the local glass structure around the metal particles as well as to detect incomplete metal reduction or residues tracing the preparation route, hence making it possible to differentiate between genuine artefacts and fakes.

Abstract: Metallic lustre decorations of glazed ceramics, which appeared in Mesopotamia during the 9th century AD, can be considered nowadays as an historical example of controlled nanotechnology for optical devices. Their surprising optical properties are directly due to metallic nanoparticles that Islamic potters were able to bury in the first layers of glaze through empirical chemical means. Lustre technology is fascinating and many papers have been devoted to this subject. Many lustre samples have been investigated with the most modern equipment such as the synchrotron radiation, electron microscopy, micro-Raman spectroscopy and other spectroscopic methods. This decor made in the twelfth century during the Fatimid dynasty shows a quasi-perfect double layer of nanoparticles confirming the high technological mastery of this civilization. Moreover, up to now, no lustre has been found with an organization of nanoparticles as elaborate as the decor presented here.

Abstract: Optical microscopy allows observation of details of the order of micrometers. In an electron microscope that uses an electron beam to make an image, the resolution is a thousand times better. It becomes possible to observe details of the nanometer (nm) in conventional mode and order of the Angstrom (1 Å = 0.1 nm) in high resolution mode. This technique requires a delicate preparation of samples to be sufficiently thin (≤ 100 nm) to allow the passage of electrons to an observation in transmission. The transfer of energy between incident electrons and atoms in the sample are operated through energy loss spectroscopy (EELS) and X-ray emission (EDX) to perform a chemical analysis of the observed object. The purpose of this paper is to show, through some examples, the potential of transmission electron microscopy and related techniques in the study of structure and composition of heritage materials.

Abstract: The description and identification of corrosion products formed on archaeological iron artefacts need various approaches at different observation scales. Among analytical techniques available to document phase structure at the microscopic range, Raman spectroscopy offers sensitivity and discrimination between iron corrosion products with an easy implementation. Results obtained for iron artefacts corrosion in soils and atmosphere are presented. Corrosion forms observed for anoxic and aerated soils on one hand and indoor atmosphere on the other are documented. Beyond the identification and organisation of corrosion products through hyperspectral imaging, Raman micro-spectroscopy could also provide quantitative phase proportions which will be needed in the proposition of reactivity diagnosis indicators.

Abstract: The present work focuses on the characterization of structural modifications in bone material induced by heating at low temperatures (90 - 250°C). This is of outmost importance when archaeological bone material is concerned. Changes occurring in the structure of the type I collagen and of the mineral-organic arrangement are especially investigated. This precise characterization required the combination of complementary analytical techniques: Differential Scanning Calorimetry (DSC) for global analysis of the collagen state of conservation, Scanning Electron Microscopy coupled with an Energy Dispersive X-Ray system (SEM-EDX), micro-Proton-Induced X-ray and Gamma-ray Emission (micro-PIXE/PIGE) for chemical analysis of the mineral fraction, Infrared microspectroscopy in attenuated total reflectance mode (micro-ATR-FT-IR) combined with curve-fitting for microscopic investigations and Transmission Electron Microscopy (TEM) on ultrathin sections to characterize the modifications in the mineral/organic interface at nanoscale. New criteria characterizing the effect of a thermal treatment at low temperatures on the bone structure from the macroscopic to the nanoscale were determined. There are namely a broadening of the Haversian canals, the inversion of the turns to -sheet ratio in the collagen structure determined by decomposition of the amide I IR band as well as a shift of amide II IR band position with the heating temperature to lower wavenumbers. At nanoscale, melting of the organic phase and clustering of hydroxyapatite (HAP) bone crystals can be observed. For comparison, unheated archaeological bones have been analyzed in order to test if the heat-induced modification can be distinguished from diagenetic alterations, generally dissolution-recrystallisation processes, in soils.