Hydrogen-induced morphotropic phase transformation of single-crystalline vanadium dioxide nanobeams

Woong Ki Hong, Jong Bae Park, Jongwon Yoon, Bong Joong Kim, Jung Inn Sohn, Young Boo Lee, Tae Sung Bae, Sung Jin Chang, Yun Suk Huh, Byoungchul Son, Eric A. Stach, Takhee Lee, Mark E. Welland

Research output: Contribution to journalArticlepeer-review

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Abstract

We report a morphotropic phase transformation in vanadium dioxide (VO 2) nanobeams annealed in a high-pressure hydrogen gas, which leads to the stabilization of metallic phases. Structural analyses show that the annealed VO2 nanobeams are hexagonal-close-packed structures with roughened surfaces at room temperature, unlike as-grown VO2 nanobeams with the monoclinic structure and with clean surfaces. Quantitative chemical examination reveals that the hydrogen significantly reduces oxygen in the nanobeams with characteristic nonlinear reduction kinetics which depend on the annealing time. Surprisingly, the work function and the electrical resistance of the reduced nanobeams follow a similar trend to the compositional variation due mainly to the oxygen-deficiency-related defects formed at the roughened surfaces. The electronic transport characteristics indicate that the reduced nanobeams are metallic over a large range of temperatures (room temperature to 383 K). Our results demonstrate the interplay between oxygen deficiency and structural/electronic phase transitions, with implications for engineering electronic properties in vanadium oxide systems.

Original languageEnglish
Pages (from-to)1822-1828
Number of pages7
JournalNano Letters
Volume13
Issue number4
DOIs
StatePublished - 10 Apr 2013

Keywords

  • compositional variation
  • hydrogen annealing
  • metal-insulator transition
  • Morphotropic transformation
  • reduction
  • vanadium dioxide

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