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Separation of valence states in thin films with mixed V2O5 and V7O16 phases

Huotari, J.; Cao, W.; Niu, Y. LU ; Lappalainen, J.; Puustinen, J.; Pankratov, V.; Lloyd Spetz, A. and Huttula, M. (2016) In Journal of Electron Spectroscopy and Related Phenomena 211. p.47-54
Abstract

Among the other applications, vanadium oxide thin films are considered to be excellent candidates for gas sensing. To understand the origins of the sensing capability, we carried out X-ray photoelectron and X-ray absorption spectroscopy measurements to determinate the surface valence states of thin films with mixed V7O16 and V2O5 compounds. Thin films were fabricated by pulsed laser deposition, and the crystal structure and symmetry of the deposited films was studied using grazing incidence X-ray diffraction and Raman spectroscopy. These results together with X-ray photoelectron and absorption spectra showed that the thin-film crystal structures varied between orthorhombic... (More)

Among the other applications, vanadium oxide thin films are considered to be excellent candidates for gas sensing. To understand the origins of the sensing capability, we carried out X-ray photoelectron and X-ray absorption spectroscopy measurements to determinate the surface valence states of thin films with mixed V7O16 and V2O5 compounds. Thin films were fabricated by pulsed laser deposition, and the crystal structure and symmetry of the deposited films was studied using grazing incidence X-ray diffraction and Raman spectroscopy. These results together with X-ray photoelectron and absorption spectra showed that the thin-film crystal structures varied between orthorhombic V2O5 phase and another phase of triclinic V7O16. X-ray photoelectron spectroscopy was used to quantitatively confirm the high amount of V4+ ions on surfaces of the films, especially of films with V7O16 phase present. This result was confirmed in the quantitative analysis of the V2p near-edge X-ray absorption spectra. Through the observed electronic structures, it was found that in addition to unique crystal structure and morphology, the enhanced gas sensitivity of these layers is attributed to the increase in the amount of surface oxygen vacancies.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Oxygen vacancies, Thin film, VO, Vanadium oxides
in
Journal of Electron Spectroscopy and Related Phenomena
volume
211
pages
8 pages
publisher
Elsevier
external identifiers
  • scopus:84976872296
  • wos:000382343100006
ISSN
0368-2048
DOI
10.1016/j.elspec.2016.06.001
language
English
LU publication?
yes
id
07084283-5e4a-4114-a22b-f6c6abe85db2
date added to LUP
2016-12-15 10:51:23
date last changed
2017-09-18 11:31:22
@article{07084283-5e4a-4114-a22b-f6c6abe85db2,
  abstract     = {<p>Among the other applications, vanadium oxide thin films are considered to be excellent candidates for gas sensing. To understand the origins of the sensing capability, we carried out X-ray photoelectron and X-ray absorption spectroscopy measurements to determinate the surface valence states of thin films with mixed V<sub>7</sub>O<sub>16</sub> and V<sub>2</sub>O<sub>5</sub> compounds. Thin films were fabricated by pulsed laser deposition, and the crystal structure and symmetry of the deposited films was studied using grazing incidence X-ray diffraction and Raman spectroscopy. These results together with X-ray photoelectron and absorption spectra showed that the thin-film crystal structures varied between orthorhombic V<sub>2</sub>O<sub>5</sub> phase and another phase of triclinic V<sub>7</sub>O<sub>16</sub>. X-ray photoelectron spectroscopy was used to quantitatively confirm the high amount of V<sup>4+</sup> ions on surfaces of the films, especially of films with V<sub>7</sub>O<sub>16</sub> phase present. This result was confirmed in the quantitative analysis of the V2p near-edge X-ray absorption spectra. Through the observed electronic structures, it was found that in addition to unique crystal structure and morphology, the enhanced gas sensitivity of these layers is attributed to the increase in the amount of surface oxygen vacancies.</p>},
  author       = {Huotari, J. and Cao, W. and Niu, Y. and Lappalainen, J. and Puustinen, J. and Pankratov, V. and Lloyd Spetz, A. and Huttula, M.},
  issn         = {0368-2048},
  keyword      = {Oxygen vacancies,Thin film,VO,Vanadium oxides},
  language     = {eng},
  month        = {08},
  pages        = {47--54},
  publisher    = {Elsevier},
  series       = {Journal of Electron Spectroscopy and Related Phenomena},
  title        = {Separation of valence states in thin films with mixed V<sub>2</sub>O<sub>5</sub> and V<sub>7</sub>O<sub>16</sub> phases},
  url          = {http://dx.doi.org/10.1016/j.elspec.2016.06.001},
  volume       = {211},
  year         = {2016},
}