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

This article examines the influence of the composition on the Raman spectra of lead silicate glass. Modem 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 SiO4 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. Copyright (C) 2008 John Wiley & Sons, Ltd.