Nanoparticles in Lustre Reconstructions
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Nanoparticles in Lustre Reconstructions P. Fredrickx1,2, J. Verbeeck1, D. Schryvers1, D. Hélary3, E. Darque-Ceretti3 1 EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium 2 KIK-IRPA, Jubelpark 1, B-1000 Brussels, Belgium 3 Ecole des Mines de Paris, CEMEF (CNRS UMR 7635), BP 207, F-06904 Sophia-Antipolis cedex, France ABSTRACT It is increasingly apparent that the spatial distribution of Ag and Cu nanoparticles in lustre glazes is an important factor in determining the colour displayed by the decoration. Using STEM-EDX of cross sections, this distribution can easily be imaged, as is demonstrated in two modern reconstructions of lustre decorations from Granada, Spain. On the nanoscale, the difference in colour can be related to a different spatial distribution of the Ag and Cu particles, with the brownish gold variant consisting of a top layer of Ag nanoparticles with an underlying layer of Cu nanoparticles while in the yellowish golden lustre Cu specks are unevenly dispersed. INTRODUCTION A lustre layer is a decorative layer applied to a white opaque glaze for pottery that is famous for its metallic sheen. It has been applied to embellish ceramics since its invention in the 9th century A.D. in Iraq and then was spread all over the Mediterranean basin [see e.g. 1, 2]. Lustreware is effectively a multi-layered structure. On a macroscopic level the base is formed by the ceramic body. This is covered by a thick white layer (about 200 µm thick), opacified by large (i.e. between 150 nm and 300 nm diameter [3]) crystals of SnO2. In the upper regions of this white glaze, nanoparticles constituting the lustre layer are present. As will be demonstrated, the lustre layer can in itself have a nanoscopically layered structure. Nanoparticle colours in historic context can also be seen in stained-glass windows. Ag nanoparticles in a glass matrix display a surface plasmon resonance (SPR) frequency around 410 nm, that can be seen as a yellow colour, for example, in stained-glass windows. Cu nanoparticles have an SPR frequency of about 560 nm, which is used, for example, in the red glass areas of stained-glass windows. In lustre layers, both types of particle are present simultaneously. This, in combination with a higher particle density produces new effects and different colours than in the transparent stained-glass windows. It becomes clear that the colour of a lustre decoration layer depends on more parameters than only the quantitative composition of elements or element ratios [4]: it also depends on the microand nanostructure of the lustre layer, which can be revealed by TEM. The systematic investigation of the relationship among the fabrication parameters, the resulting nanoparticle distribution and the resulting colour is an ambitious, yet essential, project for the future. As a first step towards the realisation of such an endeavour, this contribution reports the results obtained in two reconstructions of lustre ware made by a modern potter in Granada, Spain, who works in the traditional way. Th
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