In-situ nanoscale dynamics of nanoparticles using variable temperature TEM imaging

Tutkimustuotos: AbstraktiScientific


Traditionally, TEM has been used to investigate the morphology, structures, and chemical compositions at atomic scale. However, conventional imaging does not offer opportunities to study materials dynamics under various physical parameters. In this context, in-situ TEM allows observation of the dynamic behavior of materials in response to external stimuli such as temperature, gas environment, stress, and electric or magnetic fields at nanoscale and even atomic scale. In recent years, in-situ solid-state TEM with specially designed specimen holders and MEMS chips have allowed detailed studies on agglomeration and coalescence, melting and crystallization, transformations between crystal structures, and the formation of new phases by solid-state diffusion driven by temperature, voltage, or mechanical strain. Understanding nanoscale dynamics of
coalescence is a crucial process in the bottom-top strategy for the development of nano or microstructure with broad scientific and technological applications in the field of, for example, bio and chemical sensors, protein separation, recovery of catalysts, surface-enhanced Raman scattering and data storage devices.
In this work, we monitored the real-time, structural changes of gold nanoparticles (AuNPs) using in-situ TEM imaging. We used citrate-capped gold nanoparticles of two different sizes (5.0 nm and 10.0 nm) and studied their dynamics by in-situ heating with a temperature range between 25 °C to
1000 °C.
Figure 1 shows snapshots from in-situ TEM imaging as a function of temperature when two small nanoparticles were under close proximity with a larger nanoparticle. Upon heating the sample two small nanoparticles (NPs) approached the bigger nanoparticle (NP) (10 nm) for coalescence (Figure 1a). Our results suggest that the larger nanoparticles remain stable until 700 °C. Where the coalescence of smaller particles occurs between 400 °C to 700 °C depending on their size. The melting of NP was initiated from the shell by changing to an amorphous or liquid-like structure. At higher temperatures, the change in the orientation of the lattice plane in the NP, by 68.5°, was also observed. The data after 700 °C is not given because the NP under observation was completely changed to amorphous form with the change in the shape as shown in Figure 1k, where both are considered two different ways of NP melting. Our results provide crucial insights into the effect of size, shape, and proximity of nanoparticles on thermal stability, coalescence and melting.
TilaJulkaistu - 2023
OKM-julkaisutyyppiEi OKM-tyyppiä
TapahtumaSCANDEM 2023: 73rd Annual Meeting of the Nordic Microscopy Society - Ångström laboratory in Uppsala, Sweden, Uppsala, Ruotsi
Kesto: 12 kesäk. 202315 kesäk. 2023


ConferenceSCANDEM 2023


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