Study of environmental degradation of silver surface
- Citation:
- Águas, H., Silva Viegas Pereira Fortunato Martins R. J. C. M. "Study of environmental degradation of silver surface." Physica Status Solidi (C) Current Topics in Solid State Physics. 5 (2008): 1215-1218.
Abstract:
To evaluate the evolution of a dark film formation on silver surface objects, several coupons were catalogued and place inside a museum, located in an urban area. The changes on these samples were measured by spectroscopic ellipsometry, in periods of months. This technique allows the reduction of the coupons exposure time, in several months, due to its high sensitivity to surface modifications, with acceptable results for the evaluation of its degradation. The thicknesses of the degradation layers and the optical properties of silver oxide, chloride and sulphide reference samples were determined using a mixture of Tauc-Lorentz and Drude models. The composition of the silver corrosion layer was determined by fitting the layer using a Bruggeman Effective Medium Approximation (BEMA) of the three products plus voids. It was found that the thickness of the layer depends in the placement of the coupons, namely, inside or outside displayers. The average film thickness after 6 months was of 180 Å and 280 Å, inside and outside the displayers, respectively. The main compounds found in the layers were the silver chlorides and sulphides, which composition changed with the thickness of the layer, and the exposition time. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.
Notes:
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