Combined use of SA‐XPS, XRD and SEM + EDS for the micro‐chemical characterisation of Ag‐based archaeological artefacts

Abstract

The precious metallic artefacts are particularly interesting from a historical, artistic and economical point of view because they were used as jewels, amulets or artistic items and also for currency, medium of exchange and form of saving. By means of the combined use of XPS, X‐ray diffraction, SEM + energy dispersive spectrometry and optical microscopy, the micro‐chemical surface structure of the corrosion products grown on archaeological Ag‐based artefacts has been investigated in the present work. The obtained results allowed the identification of the corroding agents coming from the surrounding environment where the artefacts have been found, stored or exhibited. The experimental findings highlight the role of chloride ions that are present in the patina as chloroargyrite or corrode the copper islands scattered in the alloy giving rise to the formation of the dangerous species such as atacamite and paratacamite. Furthermore, the results shown different corrosion behaviours with the outermost layers enriched of S, Ca, Al, Si and Fe demonstrating the relationship between some soil constituents and surface alloy corrosion products giving rise to the formation of different compounds. Copyright © 2014 John Wiley & Sons, Ltd.

Microstructure and chemical composition of Roman orichalcum coins emitted after the monetary reform of Augustus (23 B.C.)

“…A multi-analytical approach 29,30 based on µ-Raman 31 , X-ray Diffraction, X-ray Photoelectron Spectroscopy 32 or micro-PIXE 33 was applied to investigate the external layers of metal object. Electrochemical analysis as Voltammetry of Immobilized Micro Particle and Electrochemical Impedance Spectroscopy 34–39 are also used to explore the state of conservation of the patina and to identify the corrosion products.…”

Archaeometric Characterisation and Assessment of Conservation State of Coins: The Case-Study of a Selection of Antoniniani from the Hoard of Cumae (Campania Region, Southern Italy)

“…It means that up to that level, the effects of corrosion are not strong enough to alter the values of the main elements [24,25]. Along with the X-ray fluorescence technique, the Raman spectroscopy is commonly used for non-destructive and non-invasive analysis on ancient coins [26][27][28], as well as the scanning electron microscopy/energy dispersive X-ray spectrometry (SEM-EDS) [29][30][31] sometimes combined with an electron micro probe analyser (EMPA) [15,[31][32][33]. Micro-invasive analyses carried out by a field emission scanning electron microscope with a focused ion beam (FIB-FESEM-EDS) may provide useful information on the microstructure and corrosion processes [32,34].…”

Non-destructive structural studies of coins from the Uzundara Fortress using X-ray diffraction and neutron tomography

“…The neutron tomography method, due to the features of the neutron beam interaction while passing through the elements of the investigated object with different chemical compositions, thickness and density, makes it possible to obtain detailed information about the internal structure of metal coins [16,19] with a spatial resolution at the micron level [20], as well as to obtain a virtual three-dimensional model of the coin for further analysis. The complex of the above-mentioned experimental methods of structural diagnostics makes it possible to reveal internal defects or cracks, identify the corrosion spread, and investigate the phase composition in copper [13] and silver [21,22] numismatic objects.…”