XANES investigation of the yellow Sb-Pb pigment used in colour mixtures in Portuguese ceramics during the 18-19th centuries

M. Larsson Coutinhoa,b,c, T. Pena da Silvad, E. Figueiredoc , E. Salas-Colerae, J.P. Veigac

   aLaboratório Hercules,Universidade de Évora, 7000-809 Évora, Portugal

b CENIMAT/I3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Quinta da Torre, 2829-516 Caparica, Portugal

  c Vicarte, VICARTE - Vidro e Cerâmica para as Artes ,Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Quinta da Torre, 2829-516 Caparica, Portugal

d LNEG (National Laboratory for Energy and Geology), Mineral Resources & Geophysics Research Unit, Estrada da Portela, Apt. 7586, 2610-999 Amadora, Portugal

e SpLine, Spanish CRG Beamline, European Synchrotron Radiation Facility (ESRF), 71 Avenue des Martyrs, 38000 Grenoble, France 

During the 18-19th century the colour palette of the Portuguese ceramics was characterized by the use of yellow, orange, green and blue colours. In tin opacified lead-alkali glazes, such as the glazes used in the majolica technique, the yellow colour can be obtained by Sb-Pb or Sb-Sn-Pb pigments. This is the case of antimony-containing pyrochlore-type double oxides such as bindheimite, a yellow pigment with approximate formulae Pb2Sb2O7. Other colours such as orange, grey and green are a mixture of the yellow pigment with iron or cobalt.

To ascertain antimony speciation and to better understand pigment incorporation in ancient glazes it is necessary to study both antimony and lead speciation in the glaze. Accordingly, the XAFS characterization of both Sb K-edge and Pb L-edge is the optimal methodology. Samples analysed are unique majolica-type polychrome from 18-19th century Portuguese manufacture and Portuguese tiles and faience objects from Portuguese Factories (Bandeira, Estremoz and Fervença). Here reported are the first results on XANES analysis for the clarification of the structural role of Sb and Pb in the glazes for comparison with results from 17th century tile glazes. The detailed structure of an absorption edge (XANES) is the answer on information on the bonding state and speciation of an element responding also to the geometry of the atomic environment. XANES has been successfully applied to this type of studies for other type of tile glazes and glasses being the answer to questions of this specific majolica-type glazes [1-6].



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Abstract presented in the Conference Materiais 2019, 14-17 Abril 2019, Lisboa, Portugal