6533b823fe1ef96bd127ed05
RESEARCH PRODUCT
Changes in the local structure of nanocrystalline electrochromic films of hydrated nickel vanadium oxide upon ozone-induced coloration
Juris PuransAndris AzensC. G. GranqvistAlexei KuzminGunnar A. NiklassonE. Avendaosubject
Materials scienceExtended X-ray absorption fine structureAbsorption spectroscopyAnalytical chemistrychemistry.chemical_elementSputter depositionCondensed Matter PhysicsAtomic and Molecular Physics and OpticsNanocrystalline materialVanadium oxideXANESNickelchemistryElectrochromismMathematical Physicsdescription
Hydrated thin films of nickel vanadium oxide (Ni1−xVxOy), made by reactive DC magnetron sputtering, were studied by x-ray absorption spectroscopy at the Ni and V K-edges using synchrotron radiation. The XANES signals were analysed within the full-multiple-scattering formalism, whereas EXAFS data were modelled within the multi-shell multiple-scattering approach. We found that transparent films exhibit a nanocrystalline NiO-type structure with homogeneous distribution of V ions substituting Ni ions. Exposure of the films to ozone resulted in dark brown coloration associated with an appearance of Ni3+ ions and accompanied by a modification of the local electronic and atomic structures of the V and Ni ions. The largest changes occurred in the environment of the V ions, which presumably change their valence state from V4+ to V5+ and displace into off-centre positions by ~0.4 A.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2005-01-01 |