Raman and X‐ray fluorescence glaze characterisation of Maria Keil's decorative tile panels.

A set of decorative contemporary tile panels, created by the Portuguese artist Maria Keil (1914–2012) for the Lisbon metro stations, was studied under a noninvasive analytical methodology. This methodology combines X‐ray fluorescence spectrometry (μ‐XRF) and Raman spectroscopy in microscopic (μ‐Raman) mode for an elemental and structural composition characterisation of the glaze (glass matrix and network modifiers such as fluxes, opacifiers and colouring agents). μ‐XRF quantitative evaluation of the glassy matrix shows that all glazes have a lead silicate glass base. Results obtained by the combined use of μ‐XRF and μ‐Raman show that a zirconium‐based opacifier was used. Naples yellow (Pb2Sb2O7), lead–tin yellow type II (Pb(Sn,Si)O3), Pb–Sn–Sb triple oxide, cobalt blue (CoAl2O4), chromium oxide (Cr2O3) and malayite sphene (CaO·SnO2·SiO2) have been identified by μ‐Raman as some of the colouring agents, either used by themselves or in mixtures for obtaining the desirable colours intended by the artist. [ABSTRACT FROM AUTHOR]