How does temperature influence the nanoscale growth of Ag particles?

Serin Lee, Frances Ross, and their colleagues at MIT published recent work using their Hummingbird Scientific in-situ liquid-electrochemistry TEM sample holder to investigate the growth of nanocrystals formed under the redox environment created by electron beam interactions with aqueous silver nitrate. A thin film heater in the liquid cell allowed variation of temperature which led to variation in nanocrystal growth rates and morphology.

Figure 1. a) Plot of volumetric growth extracted from TEM micrographs. TEM videos showing Ag nanocrystal growth at b) 25 °C, c) 50 °C, and d) 70 °C. 25 °C and 50 °C show island morphologies while 70 °C shows rapid dendrite formation. Copyright © 2023 American Chemical Society

Ag nanocrystals were grown in the liquid cell at temperatures of 25 °C, 50 °C, and 70 °C with a constant dose rate from the TEM e- beam. At 25 °C and 50 °C, the nanocrystals nucleate as hemispherical islands on the surface of the SiN window, while at 70 °C rapid growth of blade-like dendrites is observed. Growth rate increases generally with temperature, but much more rapidly with a new growth mode at 70 °C. A kinetic model was developed to predict the temperature dependence of the solution chemistry, but suggested that ion supply and diffusivity changes are insufficient to account for the difference in these growth modes. The rapid dendrite formation was attributed rather to faster surface attachment and reduced competition for fewer nucleation sites. The team demonstrated the utility of the Hummingbird Scientific liquid cell TEM sample holder for radiolytic crystallization studies, and produced a comprehensive temperature-dependent radiolysis model to inform future experiments.

Reference:

Serin Lee, Nicholas M. Schneider, Shu Fen Tan, and Frances M. Ross, ACS Nano 17 5609-5619 (2023) DOI: 10.1021/acsnano.2c11477

Full paper Copyright © 2023 American Chemical Society

 

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