Optical anisotropy of pristine and reduced V2O5(010)

Abstract The optical anisotropy of pristine and reduced single crystalline (010) orientated $$\hbox {V}_{2}\hbox {O}_{5}$$ is presented. The reduction of $$\hbox {V}_{2}\hbox {O}_{5}$$ is complex due to the abundance of V-O phases, strong dependence on the reducing conditions and multitude of reduct...

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Main Authors: Brian Walls, Oisín Murtagh, Chris M. Smith, Daragh Mullarkey, Dmitry Shulyatev, Karsten Fleischer, Ainur Zhussupbekova, Igor V. Shvets
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-07519-z
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author Brian Walls
Oisín Murtagh
Chris M. Smith
Daragh Mullarkey
Dmitry Shulyatev
Karsten Fleischer
Ainur Zhussupbekova
Igor V. Shvets
author_facet Brian Walls
Oisín Murtagh
Chris M. Smith
Daragh Mullarkey
Dmitry Shulyatev
Karsten Fleischer
Ainur Zhussupbekova
Igor V. Shvets
author_sort Brian Walls
collection DOAJ
description Abstract The optical anisotropy of pristine and reduced single crystalline (010) orientated $$\hbox {V}_{2}\hbox {O}_{5}$$ is presented. The reduction of $$\hbox {V}_{2}\hbox {O}_{5}$$ is complex due to the abundance of V-O phases, strong dependence on the reducing conditions and multitude of reduction pathways. Different phases close in stoichiometry can exhibit drastically different electronic and optical properties. Reflectance anisotropy spectroscopy (RAS) provides a non-destructive optical probe that can be employed in real-time to monitor changes in thin films. Pristine $$\hbox {V}_{2}\hbox {O}_{5}$$ (010) exhibits strong anisotropy with significant features beyond the optical bandgap of 2.5 eV. Axially resolved optical constants, extracted using ellipsometry, facilitate the calculation of the RAS which is in excellent agreement with the experimental data. Vacuum annealing has been performed at four different temperatures and X-ray Diffraction and RAS have been conducted after each anneal. Depending on the anneal temperature, different phases are introduced into the $$\hbox {V}_{2}\hbox {O}_{5}$$ crystal including $$\hbox {V}_{4}\hbox {O}_{9}$$ , $$\hbox {V}_{6}\hbox {O}_{13}$$ and $$\hbox {VO}_{2}$$ . Spectral features of each of these phases are identified. $$\hbox {V}_{6}\hbox {O}_{13}$$ is understood in terms of the axially resolved optical constants from the literature, while isotropic $$\hbox {VO}_{2}$$ modifies the total reflection once it undergoes its semiconductor-to-metal phase transition at 340 K. This understanding of the optical response of the ideal single crystal facilitates applying RAS to monitor the growth and changes of $$\hbox {V}_{2}\hbox {O}_{5}$$ thin films in real time.
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spelling doaj-art-b6da76aaa525425db6201675b621095c2025-08-20T03:38:11ZengNature PortfolioScientific Reports2045-23222025-07-0115111010.1038/s41598-025-07519-zOptical anisotropy of pristine and reduced V2O5(010)Brian Walls0Oisín Murtagh1Chris M. Smith2Daragh Mullarkey3Dmitry Shulyatev4Karsten Fleischer5Ainur Zhussupbekova6Igor V. Shvets7School of Physics and Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College DublinSchool of Physics and Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College DublinSchool of Physics and Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College DublinSchool of Physics and Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College DublinMaterials Modeling and Development Laboratory, NUST MISISSchool of Physical Sciences, Dublin City UniversitySchool of Physics and Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College DublinSchool of Physics and Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College DublinAbstract The optical anisotropy of pristine and reduced single crystalline (010) orientated $$\hbox {V}_{2}\hbox {O}_{5}$$ is presented. The reduction of $$\hbox {V}_{2}\hbox {O}_{5}$$ is complex due to the abundance of V-O phases, strong dependence on the reducing conditions and multitude of reduction pathways. Different phases close in stoichiometry can exhibit drastically different electronic and optical properties. Reflectance anisotropy spectroscopy (RAS) provides a non-destructive optical probe that can be employed in real-time to monitor changes in thin films. Pristine $$\hbox {V}_{2}\hbox {O}_{5}$$ (010) exhibits strong anisotropy with significant features beyond the optical bandgap of 2.5 eV. Axially resolved optical constants, extracted using ellipsometry, facilitate the calculation of the RAS which is in excellent agreement with the experimental data. Vacuum annealing has been performed at four different temperatures and X-ray Diffraction and RAS have been conducted after each anneal. Depending on the anneal temperature, different phases are introduced into the $$\hbox {V}_{2}\hbox {O}_{5}$$ crystal including $$\hbox {V}_{4}\hbox {O}_{9}$$ , $$\hbox {V}_{6}\hbox {O}_{13}$$ and $$\hbox {VO}_{2}$$ . Spectral features of each of these phases are identified. $$\hbox {V}_{6}\hbox {O}_{13}$$ is understood in terms of the axially resolved optical constants from the literature, while isotropic $$\hbox {VO}_{2}$$ modifies the total reflection once it undergoes its semiconductor-to-metal phase transition at 340 K. This understanding of the optical response of the ideal single crystal facilitates applying RAS to monitor the growth and changes of $$\hbox {V}_{2}\hbox {O}_{5}$$ thin films in real time.https://doi.org/10.1038/s41598-025-07519-zMetal oxidesVanadium oxidesThermal oxide reductionReflectance anisotropy spectroscopyMetal-to-insulator transitionOptical reflectivity
spellingShingle Brian Walls
Oisín Murtagh
Chris M. Smith
Daragh Mullarkey
Dmitry Shulyatev
Karsten Fleischer
Ainur Zhussupbekova
Igor V. Shvets
Optical anisotropy of pristine and reduced V2O5(010)
Scientific Reports
Metal oxides
Vanadium oxides
Thermal oxide reduction
Reflectance anisotropy spectroscopy
Metal-to-insulator transition
Optical reflectivity
title Optical anisotropy of pristine and reduced V2O5(010)
title_full Optical anisotropy of pristine and reduced V2O5(010)
title_fullStr Optical anisotropy of pristine and reduced V2O5(010)
title_full_unstemmed Optical anisotropy of pristine and reduced V2O5(010)
title_short Optical anisotropy of pristine and reduced V2O5(010)
title_sort optical anisotropy of pristine and reduced v2o5 010
topic Metal oxides
Vanadium oxides
Thermal oxide reduction
Reflectance anisotropy spectroscopy
Metal-to-insulator transition
Optical reflectivity
url https://doi.org/10.1038/s41598-025-07519-z
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