| AVS 59th Annual International Symposium and Exhibition | |
| Thin Film | Monday Sessions |
| Session TF-MoM |
| Session: | ALD Enabled Applications |
| Presenter: | A.E. Marquardt, University of Maryland |
| Authors: | A.E. Marquardt, University of Maryland E. Breitung, E-Squared Art Conservation Science G. Gates, The Walters Art Museum T. Drayman-Weisser, The Walters Art Museum G.W. Rubloff, University of Maryland R.J. Phaneuf, University of Maryland |
| Correspondent: | Click to Email |
In this work we investigate atomic layer deposition (ALD) to create transparent oxide diffusion barrier coatings to reduce the rate of tarnishing for silver objects in museum collections. Elevated heating and H2S pressure tests determined the effect of various thicknesses of Al2O3 ALD thin films, ranging from 5 to 100nm thick, and the effect of annealing temperature on the thickness of the tarnish layer (Ag2S) created at the interface of the ALD coating and the silver substrate. Reflectance spectroscopy and an integrated sphere spectrophotometer were used to measure the thickness of the tarnish layer and indicate the effectiveness of the Al2O3 ALD thin films in reducing the tarnishing rate of silver while minimally affecting the visual appearance of the silver. X-ray photoelectric spectroscopy (XPS), and time of flight secondary ion mass spectroscopy (TOF-SIMS) analysis determined the concentration profile of sulfur through the ALD oxide film. A model for predicting the tarnishing kinetics of sulfur diffusion through ALD oxide films is established, influenced by the composition of the alloy, phase of sulfide at the interface, and non-uniformity of diffusion due to pinhole and concentration dependence. Evidence was found for the slow diffusion of sulfur through the bulk of the films and faster diffusion through pinholes in the ALD oxide films.