Abstract
We report the first experimental application of surface-enhanced Raman scattering (SERS) to the study of the structural phase transition of vanadium dioxide (VO2). Using arrays of gold-capped VO2 nanoparticles (Au+VO2NPs) and a VO2film covered with Au islands, we obtained the temperature evolution of the SERS intensity with respect to the amount of accessible material across the monoclinic-tetragonal- monoclinic transformation cycle of VO2. The smallest Au+VO 2NPs displayed the largest deviations from the bulk transition temperatures to complete the transformation, resulting in the widest thermal hysteresis, while the Au+VO2film exhibited the narrowest hysteresis. The observed size dependence agrees qualitatively with the model of defect-induced nucleation of the VO2 transition, although the magnitude of the hysteresis width and its dependence on NP size were less pronounced than those in a previous study of elastic light scattering from bare VO2NPs. The discrepancies may stem from the creation of extrinsic nucleation sites in the VO2NPs during their high-temperature processing in the presence of the Au caps; alternatively, the hystereses of the structural and electronic transitions could each have a different dependence on size. Lastly, we correlate the size dependence of the VO2SERS intensity with the scattering efficiency of the Au nanoparticles, within the framework of a modified Mie-theory calculation.
Original language | English |
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Article number | 125002 |
Journal | Journal of Optics A: Pure and Applied Optics |
Volume | 11 |
Issue number | 12 |
DOIs | |
Publication status | Published - Nov 26 2009 |
Keywords
- AuVO
- Gold (Au)
- Hybrid nanoparticles
- Hysteresis
- Mie theory
- Phase transition
- Size effects
- Surface-enhanced Raman scattering (SERS)
- Vanadium dioxide (VO)
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics