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Atomic Diffusion Induced by Electron-Beam Irradiation: An in Situ Study of Ag Structures Grown from α‑Ag2WO4

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posted on 29.11.2018, 00:00 by Júlio C. Sczancoski, Santiago Maya-Johson, Wyllamanney da Silva Pereira, Elson Longo, Edson R. Leite
In this paper, we investigate the structural and morphological changes caused by the electron-beam irradiation that led to the growth of complex extruded filaments on the surfaces of α-Ag2WO4. To provide a complete description of this phenomenon, both scanning electron microscope (SEM) and transmission electron microscope (TEM) were employed in this study. Our experimental results evidenced that the extruded material was able to exhibit growth on different crystallographic faces, depending on the kind of microscope adopted during the electron-beam irradiation. For a more complete analysis, different electron-beam current densities in TEM were used to investigate all in situ modifications in the microcrystals. For the first time, besides the metallic silver, the presence of silver oxides (Ag2O and Ag3O4) were detected in the composition of extruded material. The diffusion mechanisms related to morphological modifications in the samples irradiated in SEM and TEM were discussed in detail. The coprecipitation reaction in dimethyl sulfoxide was chosen as the synthetic route, which favored the appearance of rectangular rod-like α-Ag2WO4 microcrystals. A growth mechanism was proposed to explain the formation and growth processes of these microcrystals.