Surface mediated Ag–Hg alloy formation under ambient and vacuum conditions—AFM and XRD investigations

Thin Ag films deposited under UHV conditions on a glass support were exposed to Hg vapor at 298 K under two different conditions: vacuum, and ambient atmosphere. The influence of the amalgamation process on film topography was studied by the atomic force microscopy (AFM) method, while the composition of the amalgams was determined by means of X-ray diffraction (XRD). The obtained results indicated the different mechanism of Ag2Hg3 alloy formation depending on whether the amalgam is formed in a vacuum or under ambient atmosphere. This is discussed as a consequence of the influence of oxygen and different kinetics of the amalgamation process performed under both conditions. Heating of amalgam leads to gradual reconstruction of the alloy (370 K) and finally its decomposition (500 K), leaving strongly modified, discontinuous silver film. The ultimate nanostructure of the film depends on the transport mechanism of the silver nanounits during the amalgamation process. Therefore, Ag–Hg alloy formation and decomposition seems to be a practical and promising method for the preparation of discontinuous thin silver films of significant thickness and mesoscopic structure.