Study of the thermal annealing on structural and morphological properties of high-porosity A-WO3 films synthesized by HFCVD

M. Cruz-Leal, O. Goiz, F. Chávez, G. F. Pérez-Sánchez, N. Hernández-Como, V. Santes, C. Felipe

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6 Scopus citations

Abstract

High-porosity nanostructured amorphous tungsten OXIDE (a-WO3) films were synthesized by a Hot Filament Chemical Vapor Deposition technique (HFCVD) and then transformed into a crystalline WO3 by simple thermal annealing. The a-WO3 films were annealed at 100, 300, and 500C for 10 min in an air environment. The films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-Raman spectroscopy, high-resolution transmission electron microscopy (HR-TEM), and UV–vis spectroscopy. Results revealed that the a-WO3 films were highly porous, composed of cauliflower-like structures made of nanoparticles with average sizes of 12 nm. It was shown that the effect of annealing on the morphology of the a-WO3 films leads to a sintering process. However, the morphology is conserved. It was found that at annealing temperatures of 100°C, the a-WO3 films are of an amorphous nature, while at 300°C, the films crystallize in the monoclinic phase of WO3. The calculated bandgap for the a-WO3 was 3.09 eV, and 2.53 eV for the film annealed at 500°C. Finally, the results show that porous WO3 films preserve the morphology and maintain the porosity, even after the annealing at 500°C.

Original languageEnglish
Article number1298
JournalNanomaterials
Volume9
Issue number9
DOIs
StatePublished - Sep 2019

Keywords

  • A-WO
  • HFCVD
  • Porous tungsten oxide films

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