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

Abstract

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.

Noble‐Metal‐Assisted Fast Interfacial Oxygen Migration with Topotactic Phase Transition in Perovskite Oxides

“…However, the high thermodynamic barrier of oxygen vacancy formation due to stable metaloxygen bonding usually prohibits fast ion diffusion. [ 24 ] Thus, high operating temperature (≈700 °C) in SOFCs electrodes [ 25 ] and chemical looping [ 26 ] is usually required to guarantee reaction efficiency, which causes enormous energy dissipation. On another road, the electric field via electrolyte gating is also employed to directly drive ionic motion and even phase transition in oxides, with fast response and excellent reversibility.…”

“…(≈700 °C) in SOFCs electrodes [25] and chemical looping [26] is usually required to guarantee reaction efficiency, which causes enormous energy dissipation. On another road, the electric field via electrolyte gating is also employed to directly drive ionic motion and even phase transition in oxides, with fast response and excellent reversibility.…”

Revealing the Nature of Defects in α-Ag2WO4 by Positron Annihilation Lifetime Spectroscopy: A Joint Experimental and Theoretical Study

“…The bottom of the conduction band (CB) comprised of delocalized s and/or p orbitals presents significant dispersity, which means that it possesses high migration efficiency of photogenerated electrons. [27][28][29] Page 4 of 41…”

“…From an electronic point of view, the top of the valence band (VB) consists of unique hybridized Ag 4d and O 2p orbitals, which can leave the top position of the VB and narrow down the band gap. The bottom of the conduction band (CB) composed of delocalized s and/or p orbitals presents significant dispersity, which means that it possesses high migration efficiency of photogenerated electrons. − …”

Connecting Theory with Experiment to Understand the Sintering Processes of Ag Nanoparticles

“…The initial precursors comprising α-Ag 2 WO 4 nanorods were synthesized by chemical precipitation in dimethyl sulfoxide, in accordance with the methodology described by Sczancoski et al 57 For the in situ TEM experiments, the resulting α-Ag 2 WO 4 powder was redispersed in water by sonicating for 5 min and then one drop of the dispersion was applied to a 300 mesh Cu grid coated with an ultrathin carbon support. The TEM experiments were carried out using a TITAN Themis Cubed double-corrected microscope (ThermoFisher Scientific) equipped with a gun monochromator and extreme field emission gun (X-FEG), a high-brightness emitter gun operating at 300 kV.…”