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A XANES study of the Sn K-edge in slag by-products from tin smelting experiments [Poster]

Publication . Figueiredo, Elin; Coutinho, ML; Silva, Teresa; Salas-Colera, Eduardo; Veiga, JP

ABSTRACT: Tin was a very important alloying element in Western Europe in the production of bronze (Cu-Sn alloy) since the second millennium BC (Bronze Age), when most metallic artefacts were made of this alloy. Smelting experiments using cassiterite collected in the NW Iberian territory were made to produce tin in a very simple and small scale manner, using a small open pit structure to reproduce what could have been the manufacturing process of tin in prehistoric times. Chemical and structural analysis of the products by XRF, SEM-EDS and XRD were made to achieve a detailed knowledge of the characteristics of the materials. Additionally, an X-ray absorption near-edge structure region (XANES) study was performed on three types of slags previously identified (Type 1, Type 2 and Type 3) to obtain information on the oxidation state of Sn. The analyses were made at the European Synchrotron Radiation Facility (ESRF) at the beamline SpLine BM 25A (5-45 keV).

2020Conference object

Open access

An insight into the firing conditions of Chinese blue-and-white porcelain through XANES

Publication . Coutinho, ML; Veiga, JP; Ruivo, Andreia; Silva, Teresa; Salas-Colera, Eduardo; Bottura Scardina, Silvia; Lima, Augusta; Figueiredo, Elin; Cotte, Marine; Lima, M.M.R.A.

ABSTRACT: Chinese blue-and-white porcelain is found in archaeological excavations worldwide, being significant evidence of global trade routes and cultural exchange. Synchrotron radiation-based techniques have been applied for studying cobalt speciation to establish a correlation between the cobalt and iron oxidation state and local coordination environment in the rich blue shades of Chinese blue-and-white porcelain. However, the relationship between the firing atmosphere conditions and the speciation of cobalt has not been established yet. In this study, underglaze blue models were produced and fired in air or under reducing atmospheres to ascertain the effect of the firing atmosphere in cobalt and iron speciation. The experimental results were compared with data obtained on historical samples of ancient porcelain shards. The microstructure and colour of the produced underglaze blue models were investigated by variable pressure scanning electron microscopy (VP-SEM-EDS), using a hyperspectral imaging camera (Vis-SWIR reflectance spectroscopy) and colorimetry. The formal valence and coordination of cobalt and iron ions of the glaze were determined by X-ray absorption spectroscopy (XAS), particularly X-ray absorption near edge structure (XANES), using synchrotron radiation. Spectral features demonstrated that both cobalt and iron speciation were affected by the firing atmosphere and therefore could be used to ascertain the firing atmosphere.

2022-02Journal article

Embargoed access