Structural Stability and Phase Transitions in WO3 Thin Films
Journal
The Journal of Physical Chemistry B
Journal Volume
110
Journal Issue
21
Start Page
10430
End Page
10435
ISSN
1520-6106
1520-5207
Date Issued
2006-05-11
Author(s)
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.
Subjects
Atomic force microscopy
Ceramic materials
Energy dispersive spectroscopy
Phase transitions
Structural analysis
Transmission electron microscopy
Tungsten compounds
X ray diffraction analysis
Electrochemical device applications
Structural stability
Thin films
Publisher
American Chemical Society (ACS)
Type
journal article