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26 results on '"Borgia, I."'

7. Copper in glazes of Renaissance luster pottery: Nanoparticles, ions, and local environment.

Author

Padovani, S., Sada, C., Mazzoldi, P., Brunetti, B., Borgia, I., Sgamellotti, A., Giulivi, A., D’Acapito, F., and Battaglin, G.

Subjects
RENAISSANCE pottery, COPPER, NANOPARTICLES
Abstract

Following the recent finding that luster decorations in glazes of historical pottery consist of copper and silver nanoparticles dispersed in a glassy medium, the glaze in-depth composition and distribution of copper nanoparticles, copper ions, and their local environment have been studied in original samples of gold and red luster. The study has been fully carried out by nondestructive techniques such as Rutherford backscattering spectrometry, ultraviolet and visible spectroscopy, x-ray fluorescence, and extended x-ray absorption fine structure (EXAFS). Elemental analyses indicate that gold decorations are characterized by silver and copper, while red decorations by copper only. The color is determined mainly by metal nanoparticles. Specifically, silver nanoparticles determine the gold color, while the red color is determined by nanoparticles of copper. EXAFS measurements, carried out at the Cu K edge, indicate that in both gold and red luster copper is mostly the oxidized form (Cu[SUP+] and Cu[SUP2+]) with a large prevalence of Cu[SUP+]. States and local environment of copper ions are similar to those found in copper-alkali ion-exchanged silicate glass samples. This strongly supports the view that luster formation is mediated by a copper- and silver-alkali ion exchange as a first step, followed by nucleation and growth of metal nanoparticles. [ABSTRACT FROM AUTHOR]

Published
2003
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10. a study on late Medieval transparent-glazed pottery and archaic majolica from Orvieto (central Italy)

Author

Ricci C., Borgia I., Brunetti B.G., Sgamellotti A., Fabbri B., and Burla M.C. Polidori G.

Subjects
xrd, archaic majolica, orvieto pottery, rietveld, glazes
Abstract

Nineteen samples of medieval transparent-glazed pottery and archaic majolica from Orvieto (central Italy) were studied. they were classified by archaeological criterion as follows: five transparent-glazed fragments with green and brown decorations (first half of the 13th century), eight green transparent-glazed fragments (13th century). SEM-EDX, XRD (the Rietveld method) and XRF were used to characterise the chemical and mineralogical compositions both of the bodies and the coatings. In all of the samples, the paste is Ca-rich with CaO contents as high as 13-20 wt%. The mineralogical composition is compatible with a firing temperature about 950°C, which is the typical temperature reached in a wood kiln. No difference was observed between the bodies of transparent-and tin-glazed pottery. In the case of transparent glazes, the burial conditions lead to heavy weathering of the samples. However, on the basis of the analyses carried out innon-weathered areas, the typical composiztion is PbO 55-65 wt%, SiO2 31-35 wt%. In tin glazes, the tin is scattered on the mass of the glaze as SnO2 crystals with a concentration of 7-14 wt%. Concerning the decorations, it is established that the green colour is due to the presence of copper; while the manganese is responsible for the brown colour. These pigments, which repersent the typical colours of "archaic majolica", are spread through the glaze homogeneously, apart from one case in which there is clear evidence of manganese oxide crystals.

Published
2005

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