Raman scattering features of lead pyroantimonate compounds: Implication for the non-invasive identification of yellow pigments on ancient ceramics. Part II. in situ characterisation of Renaissance plates by portable micro-Raman and XRF studies

摘要

The effectiveness of Raman spectroscopy (using a bench-top system on standard pigments) for the characterisation of modified lead antimonate yellows was demonstrated in the already published Part I. The knowledge gained is employed here for the study of yellow glazes on genuine Renaissance plates with the aim of identifying non-invasively lead pyroantimonate compounds by portable micro-Raman equipment. The investigation was carried out directly on site, at the Victoria and Albert Museum (London, UK) and at the Museo Statale d'Arte Medievale di Arezzo (Arezzo, Italy), combining Raman and X-ray fluorescence analyses. In addition to the spectral features of both unmodified Naples yellow and Sn- and Zn-modified lead antimonate compounds, the Raman patterns related to partially modified pyrochlore structures were observed. For this reason, the possible Sn-induced modification of Naples yellow by cassiterite (SnO _2), present within the glaze as opacifier was explored on lead antimonate yellow glaze mock-ups fired at different temperatures.