Innovative methodological approach integrating SEM-EDS and TXRF microanalysis for characterization in materials science: A perspective from cultural heritage studies

Abstract

Material science is an interdisciplinary field that draws on elements of chemistry, physics, engineering and deals with designing, producing, and using a wide range of materials. The methodological approach of materials investigation is very significant in cultural heritage.

The study of Cultural Heritage materials is useful for dating, unraveling production technologies, sources and trading, and their restoration and preservation.

Archaeometry is the tool for material characterization, but it cannot always be applied in a non-destructive way: as a result, analytical techniques requiring minimum sampling are of great interest. For this, Total reflection X-ray fluorescence (TXRF) spectrometry is an effective technique, thanks to its microanalytical capabilities and the possibility of preserving the sample after its analysis, either for additional investigations or archiving purposes. It is very sensitive to period four transition elements but less effective with lighter ones. Thus, to gather the most comprehensive analysis of historic enamelled ceramics, Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) and TXRF spectrometry were combined in a novel analytical approach.

Soil standards and natural soil pigment samples were tested to validate the novel analytical approach. Na, Mg, Al, Si, K and Ca were determined with SEM-EDS analysis and used for TXRF quantification of heavier elements without adding any internal standard. The methodology to determine the total composition of artifacts, by integrating the concentrations of light elements in EDS with the data of the heavier elements obtained with TXRF, is here developed expressing elements as oxides recalculated to 100%. Recovery values for standards were found mostly within 20% of the certified values for MgO, Al₂O₃, SiO₂, K₂O, TiO₂, Cr₂O₃, MnO, Fe₂O₃, NiO, CuO, PbO and SrO. The detection capabilities for major, minor and trace elements in soil pigments prove that this novel, practically non-destructive, analytical approach has a high potential for obtaining the elemental composition of Cultural Heritage materials with broad applications.