Fundado em 1153, o Mosteiro de Alcobaça reflete os valores originais da Ordem de Cister através da sua arquitetura austera e despojada. Os ladrilhos vidrados que outrora revestiam o pavimento da abside funcionavam, assim, como um raro elemento decorativo através dos padrões criados com as suas diferentes cores e formatos. Considerados peças originais do século XIII, estes ladrilhos serão um dos primeiros exemplos de azulejaria em Portugal. O objetivo deste trabalho foi caracterizar a sua paleta cromática, através do estudo multi-analítico dos vidrados. As técnicas utilizadas foram a microscopia ótica (MO), a micro-espectrometria de emissão de raios-X induzida por partículas (μ-PIXE) e a microscopia eletrónica de varrimento com espectroscopia de raios-X por dispersão de energia (SEM-EDS). As cores identificadas nos ladrilhos, todos monocromáticos, foram o branco, o azul-turquesa, o castanho e diferentes tonalidades de verde. As análises efetuadas permitiram concluir que esta paleta se deve à presença de óxidos de estanho, de cobre e de ferro em vidrados plumbíferos. A identificação de vidrados opacificados por estanho sugere que este é um dos primeiros exemplos do uso desta tecnologia islâmica em pavimentos de cerâmica no Portugal cristão.

This work explores the combination of mu-Raman spectroscopy and scanning electron microscopy with X-ray energy dispersive spectrometry (SEM-EDS) for the study of the glazes in 15th-16th century Hispano-Moresque architectural tiles. These are high lead glazes that can be tinopacified or transparent, and present five colors: tin-white, cobalt-blue, copper-green, iron-amber, and manganese-brown. They are generally homogenous and mineral inclusions are mostly concentrated in the glaze-ceramic interface. Through SEM-EDS, these inclusions were observed and chemically analyzed, whereas mu-Raman allowed their identification on a molecular level. K-feldspars, wollastonite and diopside were the most common compounds, as well as cassiterite agglomerates that render the glaze opaque. Malayaite was identified in green glazes, and andradite and magnesioferrite in amber glazes. Co-Ni-ferrites were identified in blue glazes, as well as Ni-Fe-olivines. Manganese-brown is the color where most compounds were identified: bustamite, jacobsite, hausmannite, braunite, and kentrolite. Through the mu-Raman analysis of different areas in large inclusions previously observed by SEM, it was possible to identify intermediate phases that illustrate the reaction process that occurs between the color-conferring compounds and the surrounding lead glaze. Furthermore, the obtained results allowed inference of the raw materials and firing temperatures used on the manufacture of these tiles.

For the first time, Hispano‐Moresque glazed tiles from Portuguese and Spanish collections were studied together and compared. This work is included in a wider study tackling the technology of Hispano‐Moresque tile production from several collections in the Iberian Peninsula. While showing many similarities, differences were identified between collections, regarding both chemical and morphological characteristics. The collection from the Mosteiro de Santa Clara‐a‐Velha (Coimbra) stands out from the other collections, with higher SnO 2 content (up to 14 wt%), the highest Fe 2 O 3 contents in amber glazes and a Ca‐rich interface layer (mostly comprised of wollastonite, CaSiO 3 ). Samples from Palácio Nacional de Sintra (near Lisbon) and Seville‐attributed samples (from the Instituto Valencia de Don Juan) are chemically similar, except that most Sintra's samples display a K‐rich glaze/ceramic interface, whereas the ones from Seville exhibit both K‐rich and Ca‐rich inclusions. The samples attributed to Toledo show glazes with many inclusions, contrasting with the homogeneous glazes in most Hispano‐Moresque tiles. From these results, we identify differences that can be used as markers in future studies on Hispano‐Moresque tiles .

The glazed tiles that paved the apse of the Monastery of St. Mary of Alcobaca were a rare decorative element in the most important part of this Cistercian construction. These medieval tiles, all monochromatic, are believed to be a thirteenth-century production and represent some of the first examples of tin-opacified glazed tiles in Christian Portugal. Although lead glazes have been extensively used in medieval pavements in North-Western Europe, opaque tin-glazes are far scarcer. The technology used in this case is a testimony of mixing cultures, combining Cistercian Order traditions of building materials and techniques with the Islamic tin-glazing technology brought to the Iberian Peninsula in the tenth century. These glazes were applied on tiles of several geometric shapes to achieve the final decorative effect. For the first time, these tiles were analytically characterized to determine the chemical composition of the different colours of glaze and these differences were assessed to explain the variety of colours and shades observed. The analytical techniques used were mu-PIXE (micro-particle-induced X-ray emission), mu-Raman spectroscopy and optical microscopy. Samples selected for this study comprise all colours observed in Alcobaca tiles: white, turquoise, brown and several shades of green. Results show that the variety of colours and shades are consistent with different proportions of CuO, Fe2O3 and SnO2 in a lead-glazed matrix, together with a K-feldspar-rich white inner layer, most likely to be a slip. RESUMEO pavimento azulejar da abside do Mosteiro de Santa Maria de Alcobaca e um raro elemento decorativo na zona mais importante deste edificio Cisterciense. Estes azulejos medievais, todos monocromaticos, tem sido considerados uma producAo do seculo XIII e apresentam alguns dos mais antigos exemplares de vidrados estaniferos do Portugal cristAo. Ao contrario dos vidrados plumbiferos, profusamente utilizados em pavimentos medievais no norte da Europa, a existencia de vidrados estaniferos e rara. Esta tecnologia testemunha uma mistura de culturas, onde a tradicAo de materiais e tecnicas tipicamente utilizadas pela Ordem de Cister se funde com a tecnologia islamica do vidrado estanifero, trazido para a Peninsula Iberica no seculo X. Pela primeira vez, estes azulejos foram caracterizados analiticamente com o objectivo de determinar a composicAo quimica dos vidrados e perceber as diferencas que determinam a variedade de tonalidades observada. As tecnicas analiticas utilizadas foram a micro-espectrometria de emissAo de raios-X induzida por particulas (mu-PIXE), a micro-espectroscopia de Raman (mu-Raman) e a microscopia optica. As amostras selecionadas para este estudo incluem todas as cores observadas nos azulejos de Alcobaca: branco, turquesa, castanho e varias tonalidades de verde. Os resultados indicam que a variedade de tonalidades observada e consistente com a combinacAo de diferentes teores de CuO, Fe2O3 e SnO2 numa matriz plumbica, conjuntamente com uma camada branca - provavelmente um engobe - composta por feldspatos potassicos. O efeito decorativo final e conseguido com a aplicacAo destes vidrados sobre azulejos de diferentes formas geometricas.

A group of late 15th-early 16th century Hispano-Moresque glazed tiles from the Monastery of Santa Clara-a-Velha, in Coimbra, were, for the first time, characterised chemically and morphologically. Since the prevailing idea among art historians in Portugal is to judge the Hispano-Moresque tile heritage as Spanish production, the findings concerning technological processes were compared with the Islamic technology in the Iberian Peninsula and latter Hispano-Moresque in Spain. This study is the first analytical indicator of a production technology with some differences from the Hispano-Moresque workshops (such as Seville, Toledo, etc.) and points out to a possible local production. Five different coloured glazes were identified: white, blue, green, amber and black, all displaying high-lead content, as expected for this type of ceramics. Tin oxide was identified in high contents (7-14 wt.%) in white and blue glazes, its crystals homogenously distributed in also very homogeneous glazes, showing similarities with an Islamic glazing technology. On the other hand, Ca-rich thick glaze-ceramic interfaces were observed, with many mineral inclusions (wollastonite (CaSiO3) and also K-feldspars (general formula KAISi(3)O(8)), showing a higher resemblance with a later Hispano-Moresque technology. Other compounds were also identified from reactions involving the colour compound: malayaite (CaSnOSiO4), bustamite (CaMnSi2O6), braunite ((Mn2+, Mn3+)(6)O8SiO4), andradite (Ca3Fe2Si3O12), magnesioferrite (MgFe2O4) and a nickel ferrite (NiFe2O4). The chemical composition of this glaze-ceramic interface suggests firing temperatures between 950 degrees C and 1000 degrees C and its thickness implies a single-fire process. The chemical characterisation does not suggest different recipes or different firing processes for cuerda seca and arista tiles. (C) 2013 Elsevier Ltd. All rights reserved.