Leaching processes were studied for lead glasses having a composition similar to that of certain archaeological materials (66 wt% PbO) to determine the mechanism of the structural evolution. The glasses were leached in two static acid media (HNO3 and CH3COOH, pH 2) at 90degreesC for 35 days. Analyses were undertaken of the leaching solution (pH, inductive coupled plasma atomic emission spectrometry) and of the bulk glass (scanning electron microscopy-energy dispersive X-ray spectrometry, Rutherford backscattering spectrometry, Raman). Results show that in both acids, up to 1 day a silicon-rich surface layer is formed via typical diffusion processes. This process continues up to 35 days in the case of acetic acid. In nitric acid, one observes a stabilisation of this layer and an increase in the metal content. In both cases, Raman data are used to interpret the structural evolutions which occur in the 'gel' phase. (C) 2003 Elsevier B.V. All rights reserved. [References: 16]
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