Structural stability and phase transitions in WO3 thin films

C. V. Ramana, S. Utsunomiya, R. C. Ewing, C. M. Julien, U. Becker

Research output: Contribution to journalArticle

185 Citations (Scopus)

Abstract

Tungsten oxide (WO3) thin films have been produced by KrF excimer laser (λ = 248 nm) ablation of bulk ceramic WO3 targets. The crystal structure, surface morphology, chemical composition, and structural stability of the WO3 thin films have been studied in detail. Characterization of freshly grown WO3 thin films has been performed using X-ray diffraction (XRD), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy (RS), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) measurements. The results indicate that the freshly grown WO3 thin films are nearly stoichiometric and well crystallized as monoclinic WO 3. The surface morphology of the resulting WO3 thin film has grains of ∼60 nm in size with a root-mean-square Xrms) surface roughness of 10 nm. The phase transformations in the WO3 thin films were investigated by annealing in the TEM column at 30-500 °C. The phase transitions in the WO3 thin films occur in sequence as the temperature is increased: monoclinic → orthorhombic → hexagonal. Distortion and tilting of the WO6 octahedra occurs with the phase transitions and significantly affects the electronic properties and, hence, the electrochemical device applications of WO3.

Original languageEnglish
Pages (from-to)10430-10435
Number of pages6
JournalJournal of Physical Chemistry B
Volume110
Issue number21
DOIs
Publication statusPublished - Jun 1 2006
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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