M. Larsson Coutinho^a,b,c T. Pena da Silva^d, E. Figueiredo^b , E. Salas-Colera^e, J.P. Veiga^b 1

^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

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

^dLNEG (National Laboratory for Energy and Geology), Unity of Mineral Resources & Geophysics, Estrada da Portela-Bairro do Zambujal, Apt. 7586, 2610-999 Amadora, Portugal

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

An important set of historical samples of glazed majolica tiles form the Fronteira Palace in Lisbon, and oriental porcelains belonging to the Santa Clara Monastery in Coimbra and the Paço Ducal de Vila Viçosa were investigated. The glazes display a silica-alkali-lead glass or silica alkali glass and chromophores based on Co for the blue colouring.

To achieve a comparison between manufacturing techniques, pigments used and origin of the pieces several fragments were characterized using X-Ray Absorption Spectroscopy. XAS techniques can provide information on the structural behaviour of transition metals in the vitreous matrix - namely, their bonding state and coordination environment, that may also configure the cause of increased glaze instability along time and of final collapse due to the action of external environmental agents.

First results on the speciation of Co in the different historical fragments using XANES will be presented in an attempt to correlate and complement other measurements in Co and other transition metals in blue-and-white glazes from different periods of tile production, along with other vitreous coatings over ancient ceramics such as lustres and porcelains [4-6].

References

[1]   M.L. Coutinho, J. P. Veiga, L. C. Alves, J. Mirão, L. Dias, A. M. Lima, V. S. Muralha, M. F. Macedo (2016) Characterization of the glaze and in-glaze pigments of the nineteenth-century relief tiles from the Pena National Palace, Sintra, Portugal. Applied Physics A 122 696.

[2] M.O. Figueiredo, J.P. Veiga, T.P. Silva, J.P. Mirão, S. Pascarelli (2005) Chemistry versus phase constitution of yellow ancient tile glazes: a non-destructive insight through XAS.  Nuclear Instruments and Methods B 238 134-137.

[3] M.O. Figueiredo, J.P. Veiga, J.P. Mirão (2006) Modelling the size of red-colouring copper nanoclusters in archaeological glass beads.  Applied Physics A 83 499-502.

[4] J.P. Veiga, M.O. Figueiredo (2006) Copper blue in an ancient glass bead: a XANES study. Applied Physics A 83 547-550

[5] J.P. Veiga, M.O. Figueiredo (2008) A XANES study on the structural role of zinc in ancient tile glazes. X-ray Spectrometry 37(4) 458-461.

[6] M.O. Figueiredo, T.P. Silva & J.P. Veiga (2012) A XANES study of cobalt speciation state in blue-and-white glazes from 16th-17th century Chinese porcelains. Journal of Electron Spectroscopy and Related Phenomena 185 (3-4) 97-102..

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