SEM-EDS and XRF analyses of pellets produced with powdery clay and ceramic standards and fired at increasing temperatures showed a systematic overestimation of the abundance of heavier detected elements (K, Ca, Ti and Fe) using the conventional procedure of calibration with massive mineral/glass certified materials followed by normalization of the detected values. Errors were particularly noticeable for samples fired in the typical range of temperatures of archaeological and historical pottery (600–900 °C) and for unfired samples, and were attributed to material porosity. An extremely simple method based on the SEM-BSE image analysis is proposed for the semi-quantitative evaluation of porosity. A remarkable increase of accuracy, especially for SEM-EDS, was evidenced when the calibration is performed using a standard with porosity comparable to the samples, with regard to the pottery temperature range. Conversely, for the analysis of high-fired samples simulating porcelain (1200 °C) no substantial difference was observed with respect to the usual massive minerals/glass calibration. Finally, results showed the unsuitability of calibration performed by means of unfired pellets, for both pottery and porcelains.

Accuracy improvement by means of porosity assessment and standards optimization in SEM-EDS and XRF elemental analyses on archaeological and historical pottery and porcelain

TURCO, Francesca;DAVIT, Patrizia;COSSIO, Roberto;AGOSTINO, Angelo;OPERTI, Lorenza
2017

Abstract

SEM-EDS and XRF analyses of pellets produced with powdery clay and ceramic standards and fired at increasing temperatures showed a systematic overestimation of the abundance of heavier detected elements (K, Ca, Ti and Fe) using the conventional procedure of calibration with massive mineral/glass certified materials followed by normalization of the detected values. Errors were particularly noticeable for samples fired in the typical range of temperatures of archaeological and historical pottery (600–900 °C) and for unfired samples, and were attributed to material porosity. An extremely simple method based on the SEM-BSE image analysis is proposed for the semi-quantitative evaluation of porosity. A remarkable increase of accuracy, especially for SEM-EDS, was evidenced when the calibration is performed using a standard with porosity comparable to the samples, with regard to the pottery temperature range. Conversely, for the analysis of high-fired samples simulating porcelain (1200 °C) no substantial difference was observed with respect to the usual massive minerals/glass calibration. Finally, results showed the unsuitability of calibration performed by means of unfired pellets, for both pottery and porcelains.
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https://authors.elsevier.com/a/1UR-K,rVDBGBiF
X-ray elemental techniques, SEM-EDS, Calibration, Accuracy, Ceramic materials
Turco, F.; Davit, P.; Cossio, R.; Agostino, A.; Operti, L.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/1623042
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