Size effects in the structural phase transition of VO2 nanoparticles studied by surface-enhanced Raman scattering

E. U. Donev, J. I. Ziegler, R. F. Haglund, L. C. Feldman

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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 languageEnglish
Article number125002
JournalJournal of Optics A: Pure and Applied Optics
Volume11
Issue number12
DOIs
Publication statusPublished - Nov 26 2009

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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

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