| Autor: |
Sinha, Shyam K., Khammari, Amir, Picher, Matthieu, Roulland, Francois, Viart, Nathalie, LaGrange, Thomas, Banhart, Florian |
| Předmět: |
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| Zdroj: |
Nature Communications; 8/13/2019, Vol. 10 Issue 1, pN.PAG-N.PAG, 1p |
| Abstrakt: |
We show how the kinetics of a fast and irreversible chemical reaction in a nanocrystalline material at high temperature can be studied using nanosecond electron pulses in an electron microscope. Infrared laser pulses first heat a nanocrystalline oxide layer on a carbon film, then single nanosecond electron pulses allow imaging, electron diffraction and electron energy-loss spectroscopy. This enables us to study the evolution of the morphology, crystallography, and elemental composition of the system with nanosecond resolution. Here, NiO nanocrystals are reduced to elemental nickel within 5 µs after the laser pulse. At high temperatures induced by laser heating, reduction results first in a liquid nickel phase that crystallizes on microsecond timescales. We show that the reaction kinetics in the reduction of nanocrystalline NiO differ from those in bulk materials. The observation of liquid nickel as a transition phase explains why the reaction is first order and occurs at high rates. Detailed knowledge of the transition states and kinetics of fast reactions in nanoparticles is desirable for many applications, but challenging to access. Here the authors obtain insight in nickel oxide reduction, using single-shot electron pulses in an electron microscope with nanosecond resolution. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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