Analytical electron microscopy analysis of insulating and metallic phases in nanostructured vanadium dioxide
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Date
2024-05-03
Authors
Krpenský, Jan
Horák, Michal
Kabát, Jiří
Planer, Jakub
Kepič, Peter
Křápek, Vlastimil
Konečná, Andrea
0000-0001-6503-8294Advisor
Referee
Mark
Journal Title
Journal ISSN
Volume Title
Publisher
Royal Society of Chemistry
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Abstract
Vanadium dioxide (VO2) is a strongly correlated material that exhibits the insulator-to-metal transition (IMT) near room temperature, which makes it a promising candidate for applications in nanophotonics or optoelectronics. However, creating VO2 nanostructures with the desired functionality can be challenging due to microscopic inhomogeneities that can significantly impact the local optical and electronic properties. Thin lamellas, produced by focused ion beam milling from a homogeneous layer, provide a useful prototype for studying VO2 at the truly microscopic level using a scanning transmission electron microscope (STEM). High-resolution imaging is used to identify structural inhomogeneities while electron energy-loss spectroscopy (EELS) supported by statistical analysis helps to detect VxOy stoichiometries with a reduced oxidation number of vanadium at the areas of thickness below 70 nm. On the other hand, the thicker areas are dominated by vanadium dioxide, where the signatures of the IMT are detected in both core-loss and low-loss EELS experiments with in situ heating. The experimental results are interpreted with ab initio and semi-classical calculations. This work shows that structural inhomogeneities such as pores and cracks present no harm to the desired optical properties of VO2 samples. We utilize analytical electron microscopy with in situ heating to observe the insulator-metal transition in vanadium dioxide and to identify additional vanadium oxides across the sample exhibiting nanoscopic pores and cracks.
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Citation
NANOSCALE ADVANCES. 2024, vol. 2024, issue 13, p. 3338-3346.
https://pubs.rsc.org/en/content/articlelanding/2024/na/d4na00338a
https://pubs.rsc.org/en/content/articlelanding/2024/na/d4na00338a
Document type
Peer-reviewed
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Published version
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en