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Griesser M.,Kunsthistorisches Museum Vienna | Kockelmann W.,Rutherford Appleton Laboratory | Hradil K.,Vienna University of Technology | Traum R.,Kunsthistorisches Museum Vienna
Microchemical Journal | Year: 2016

Selected ancient Greek bronze coins held in the Coin Collection of the Kunsthistorisches Museum Vienna (KHM) were studied concerning their preservation and conservation. The coins had been minted during the Roman Imperial time (50 to 280 AD) using alloys with high lead and/or tin contents. Today a number of these highly leaded bronze coins, altogether different singular pieces, show progressive whitish corrosion in spots or well-defined areas on their surfaces. Different analytical techniques were used for the documentation and study of the different states of corrosion, the corrosion phases developing in the whitish parts as well as the cause of the specific corrosion phenomena. Further studies focused on the analysis of the corrosion phases - combining results from μ-XRD and neutron diffraction investigations - as well as on the manufacturing techniques of the antique Greek coins. The μ-XRD analysis applied a beam spot of 300 μm allowing for a localised determination of corrosion phases on the surfaces of the objects. The main corrosion products consist of metal (Cu, Pb, Cu/Sn) oxide phases. As minor components also metal sulphide and chloride phases could be assigned. To enable the distinction between different manufacturing techniques 35 coins and eight self-made 'replicas' were analysed in a non-destructive way by bulk neutron texture analysis which reveals changes in the microcrystalline structure of the alloys related to the mechanical minting processes. © 2015 Elsevier B.V. Source

Uhlir K.,Kunsthistorisches Museum Vienna | Padilla-Alvarez R.,International Atomic Energy Agency | Migliori A.,International Atomic Energy Agency | Karydas A.G.,International Atomic Energy Agency | And 8 more authors.
Microchemical Journal | Year: 2016

40 Sasanian silver coins of the emperor Khusro II (591-628) belonging to the Coin Collection of the Kunsthistorisches Museum Vienna (KHM) as well as 188 coins of the same emperor acquired at the free coin market were analyzed using micro-X-ray fluorescence analysis (μ-XRF) in the course of the research project "Sylloge Nummorum Sasanidarum". These studies revealed the presence of mercury in the XRF spectra of a bigger part of the coins. First investigations with complementary techniques showed that the mercury is present as a surface layer. Therefore, further detailed studies were performed on polished sections using the Particle Induced X-ray Emission technique with a proton microprobe (μ-PIXE) that offers quantitative and spatially resolved elemental information with micron resolution, scanning micro-X-ray fluorescence (μ-XRF) analyses for a better understanding of the elemental distribution on the surface and polished sections of the coins and finally confocal micro-XRF (3D μ-XRF or CMXRF) analyses for revealing information on the surface layering and elemental in-depth distribution. The synergistic application of these methods offered detailed and improved information on the structure of the mercury-layer on the surface of the silver coins supporting assumptions dating back to 1976/78 indicating medical treatments using Hg as basis for this phenomenon. © 2015 Elsevier B.V. Source

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