In situ Transmission Electron Microscopy observation of Ag nanocrystal evolution by surfactant free electron-driven synthesis

The study of the interaction of electron irradiation with matter and the response of the material to the passage of electrons is a very challenging problem. However, the growth mechanism observed during nanostructural evolution appears to be a broad and promising scientific field in nanotechnology. We report the in situ TEM study of nanostructural evolution of electron-driven silver (Ag) nanocrystals through an additive-free synthetic procedure. Observations revealed the direct effect of the electron beam on the morphological evolution of Ag nanocrystals through different mechanisms, such as mass transport, site-selective coalescence, and an appropriate structural configuration after coalescence leading to a more stable configuration. A fundamental understanding of the growth and formation mechanisms of Ag nanocrystals, which interact with the electron beam, is essential to improve the nanocrystal shape-control mechanisms as well as the future design and study of nanomaterials.The authors gratefully acknowledge financial support from the Brazilian research funding agencies FAPESP (2013/07296-2) and CNPq and the Spanish Brazilian program (PHB2009-0065-PC). J.A. and L.G. are grateful to Prometeo/2009/053 (Generalitat Valenciana), Ministerio de Economia y Competitividad (Spain), CTQ2012- 36253-C03-02. TEM analysis was performed in the Electron Microscopy Laboratory (LME) of the Brazilian Nanotechnology National Laboratory (LNNano)