1. A XANES study of chromophores : the case of black glass
- Author
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Peter Cosyns, Karin Nys, Simone Cagno, Hugo Thienpont, Andrea Ceglia, Kitty Baert, Wendy Meulebroeck, Gert Nuyts, Herman Terryn, Koen Janssens, Applied Physics and Photonics, Multidisciplinary Archaeological Research Institute, Brussels Photonics Team, Materials and Chemistry, Electrochemical and Surface Engineering, Art Sciences and Archaeology, Earth System Sciences, History, Metallurgy, Electrochemistry and Materials Science, and Materials and Surface Science & Engineering
- Subjects
raman ,spectroscopy ,Materials science ,Period (periodic table) ,General Chemical Engineering ,Analytical chemistry ,OXIDATION-STATE ,chemistry.chemical_element ,010502 geochemistry & geophysics ,01 natural sciences ,Spectral line ,Analytical Chemistry ,Black glass ,REDOX EQUILIBRIA ,FE3+ IONS ,0601 history and archaeology ,SODIUM-SILICATE GLASSES ,0105 earth and related environmental sciences ,IRON CONTENT ,060102 archaeology ,Magnesium ,K-EDGE ,Metallurgy ,General Engineering ,06 humanities and the arts ,Chromophore ,XANES ,Chemistry ,chemistry ,ddc:540 ,Roman glass ,Absorption (chemistry) ,Black colour ,ancient glass - Abstract
We studied the Fe K-edge X-ray absorption near edge (XANES) spectra of several Roman black glass fragments in order to determine the Fe3+/Sigma Fe ratio of these materials. The selected archaeological glass samples cover the period 1st-5th century AD in nine different sites of the North Western provinces of the Roman Empire. The fragments belong to two different compositional groups demonstrating a diachronic evolution: early Roman HMG (High Magnesia Glass) and Roman Imperial LMG (Low Magnesia Glass). The first group contains natural Fe levels (below 2 wt% as Fe2O3), while the LMG has concentrations above 5 wt%. This difference is also reflected by Fe3+/Sigma Fe values. Low iron glass was produced under strongly reducing conditions in order to obtain the black colour, with average Fe3+/Sigma Fe values approximate to 0.17. LMG glass is somewhat more oxidised (Fe3+/Sigma Fe approximate to 0.4-0.5). While HMG glass required active control of the furnace environment, LMG was made under ambient atmosphere and its higher oxidation degree is mainly determined by the chemistry of the raw glass.
- Published
- 2014
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