Correlations between Raman parameters and elemental composition in lead and lead alkali silicate glasses

Abstract

This article examines the influence of the composition on the Raman spectra of lead silicate glass. Modern and historic lead alkali glasses and high-lead glazed ceramics were analysed complementarily by Raman spectrometry and elemental techniques, either electron microprobe, proton induced X-ray emission (PIXE) or scanning electron microscope with energy dispersive spectrometry (SEM-EDS). The results showed that lead alkali silicate and high-lead silicate glasses can be easily distinguished from their Raman spectra profile. In lead alkali silicate glasses, continuous variations were observed in the spectra with the compositional change. In particular, the position of the intense peak around 1070 cm −1 was linearly correlated to the lead content in the glass. A unique decomposition model was developed for the spectra of lead alkali silicate glasses. From the combination of the Raman and elemental analyses, correlations were established between the spectral components and the composition. These correlations permitted to interpret the spectra and access additional compositional information, such as the lead content from area ratio A 990 /A 900 -1150 , the total alkali + alkaline-earth content from the area ratio A 1100 /A 900 -1150 or the silica content from the area ratio A 1150 /A 900 -1150 . In lead silicate glass containing over 25 mol% PbO, the compositional variation induced no variation in the SiO 4 network region of the Raman spectra [150-1350 cm −1 ], therefore no correlations and compositional information could be gained from the glass spectra in this range of composition. This new development of Raman spectroscopy for the analyses of glass will be very valuable for museums to not only access compositional information non-destructively but also to understand the structural changes involved with their alteration.

Nondestructive on‐site identification of ancient glasses: genuine artefacts, embellished pieces or forgeries?

“…These preliminary results seem to indicate that further interesting compositional and technological information could be derived from a deeper Raman investigation on selected samples, to be carried out in the lab using highprecision spectrometers, in order to characterize more precisely the low-wavenumber range, and to obtain reliable values for additional Raman parameters such as the polymerization index. More correlation tools, which have so far been established for limited compositional ranges, [22,24,25] would also be very useful for a better classification. Moreover, the combination of Raman and nondestructive elemental analyses (for instance using mobile Xray fluorescence (XRF) or Laser Induced Breakdown Spectroscopy (LIBS) instruments, or the external beam of a large accelerator like Aglae [19,72] ) would much improve the quality and reliability of the database.…”

Non–Destructive Raman Analysis of Ancient Glasses and Glazes

“…The identification of colouring and opacifying minerals in ancient glasses, often accompanied by the identification of glass type, has been the object of a certain number of studies on Roman mosaic tesserae [50,51,52], a wide range of beads, rings and mosaic tesserae from Ifriqiya [52], on Omayyad tesserae [53] and on trade glass beads from South Africa [33] and the Far East [54]. Further studies have regarded the corrosion processes and the identification of degradation products of glass objects in museum deposits [55][56][57] and of stained glass windows [58,59]. One reason for the scarcity of studies carried out on blown/enamelled glass could be the fragility of these artefacts, which makes them rare and not very accessible for measurements.…”

Raman Spectroscopy of cultural heritage Materials: Overview of Applications and New Frontiers in Instrumentation, Sampling Modalities, and Data Processing

“…Good correlations have been described between the lead content and Raman features of lead-based glass, as, for example the wavenumber shift of the band around 1070 cm -1 , which is described for a wide range of lead content (up to 20 mol%) [261]. For glass with varying iron content, correlations have been described between the bands centred around 980 and 1090 cm -1 (Q 2 /Q 3 areas, respectively), and Fe 2 O 3 amounts [13].…”