Chemistry versus phase constitution of yellow ancient tile glazes: A non-destructive insight through XAS

• Published in: Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms Vol. 238; no. 1-4; pp. 134 - 137
• Main Authors: Figueiredo, M.O., Veiga, J.P., Silva, T.P., Mirão, J.P., Pascarelli, S.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.08.2005
• Subjects: Pb L3-edge; Sb K-edge; Tile-glazes; XAS; Tile-glazes; Pb L3-edge; 78.55.Qr; 78.70.Dm; 78.70.En; XAS; 41.60.Ap; Sb K-edge
• ISSN: 0168-583X; 1872-9584
• DOI: 10.1016/j.nimb.2005.06.033

Using synchrotron radiation-based analytical (SRXRF) and spectroscopic (XAS) non-destructive techniques, a study was carried out on lead-rich, tin-opacified yellow glazes (silica-lime-alkali type glasses) decorating ancient tiles (17–19th century). These glasses have a rather complex chemistry, being currently assumed that the yellow pigment used for centuries – a pyrochlore-type double oxide of lead and antimony – prevails within the glaze, despite Sb(3+) being recognized as a network-forming cation in glasses. Minerals and synthetics with known crystal structure were used as model compounds to interpret X-ray absorption spectroscopy data at Sb K-edge and Pb L3-edge collected from ancient glazes. Theoretical modelling of Sb 1s XANES spectra was applied to demonstrate that antimony alone may be responsible for the yellow colour through a finely dispersed pyrochlore-type Sb-oxide, while lead remains hosted in the glassy matrix.