How can liquid cell TEM reveal nanocrystal growth modes?

Rui Zhang, Xing Lu, and their colleagues at Wuhan Institute of Technology and Huazhong University of Science and Technology published recent work using their Hummingbird Scientific in-situ liquid flow TEM sample holder to investigate the growth modes and crystallization trajectories of hexagonal zinc nanocrystals using aqueous precursors and rapid decomposition of an alkali source (hexamethylenetetramine, HMTA) induced by a high electron dose rate.

a) Video showing Nucleation and growth of hexagonal Zn NPs in liquid cell (2 × speed). b) High-resolution and HR-TEM images of Zn nanoparticle formed in the liquid cell. c) Number of nanoparticles within the field of view as a function of time with inset growth and coalescence mechanisms. Copyright © 2024 American Chemical Society

Growth trajectories and coalescence were observed in-situ revealing classical growth modes: monomer addition and Ostwald ripening (OR) as well as nonclassical coalescence. Two coalescence mechanisms: coalescence induced by surface diffusion (CIBSD) and coalescence induced by grain boundary migration (CIBGBM) were observed, which impact the relaxation process. During OR, the growth/dissolution rate increase suggests a depletion zone in the solution surrounding the nanoparticles. The study provides, for the first time using in-situ techniques, a fundamental understanding of the different stage of growth mechanisms for reactive metal nanocrystals and will inform future optimization of nanomaterial synthesis.

Reference: Rui Zhang, Yubo Wang, Yao Geng, Huxiao Xian, Lipiao Bao, Xing Lu, Crystal Growth & Design (2024) DOI: 10.1021/acs.cgd.4c00132

Full paper Copyright © 2024 American Chemical Society

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