Reduction reactions and densification during in situ TEM heating of iron oxide nanochains

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https://pubs.aip.org/aip/jap/article/122/23/234303/281614/Reduction-reactions-and-densification-during-in

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https://doi.org/10.1063/1.5004092
 http://hdl.handle.net/11603/31975

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UMBC Faculty Collection
UMBC Chemical, Biochemical & Environmental Engineering Department

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2017-12-21

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journal articles
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Citation of Original Publication

Bonifacio, Cecile S., Gautom Das, Ian M. Kennedy, and Klaus van Benthem. "Reduction Reactions and Densification during in Situ TEM Heating of Iron Oxide Nanochains." Journal of Applied Physics 122, no. 23 (December 21, 2017): 234303. https://doi.org/10.1063/1.5004092.

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This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Bonifacio, Cecile S., Gautom Das, Ian M. Kennedy, and Klaus van Benthem. "Reduction Reactions and Densification during in Situ TEM Heating of Iron Oxide Nanochains." Journal of Applied Physics 122, no. 23 (December 21, 2017): 234303. https://doi.org/10.1063/1.5004092 and may be found at https://pubs.aip.org/aip/jap/article/122/23/234303/281614/Reduction-reactions-and-densification-during-in.

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Abstract

The reduction reactions and densification of nanochains assembled from γ-Fe₂O₃ nanoparticles were investigated using in situ transmission electron microscopy (TEM). Morphological changes and reduction of the metal oxide nanochains were observed during in situ TEM annealing through simultaneous imaging and quantitative analysis of the near-edge fine structures of Fe L₂,₃ absorption edges acquired by spatially resolved electron energy loss spectroscopy. A change in the oxidation states during annealing of the iron oxide nanochains was observed with phase transformations due to continuous reduction from Fe₂O₃ over Fe₃O ₄, FeO to metallic Fe. Phase transitions during the in situ heating experiments were accompanied with morphological changes in the nanochains, specifically rough-to-smooth surface transitions below 500 °C, neck formation between adjacent particles around 500 °C, and subsequent neck growth. At higher temperatures, coalescence of FeO particles was observed, representing densification.