TY - JOUR
T1 - Study of the thermal annealing on structural and morphological properties of high-porosity A-WO3 films synthesized by HFCVD
AU - Cruz-Leal, M.
AU - Goiz, O.
AU - Chávez, F.
AU - Pérez-Sánchez, G. F.
AU - Hernández-Como, N.
AU - Santes, V.
AU - Felipe, C.
N1 - Publisher Copyright:
© 2019 by the authors. Licensee MDPI, Basel, Switzerland.
PY - 2019/9
Y1 - 2019/9
N2 - 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 500◦C 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.
AB - 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 500◦C 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.
KW - A-WO
KW - HFCVD
KW - Porous tungsten oxide films
UR - http://www.scopus.com/inward/record.url?scp=85073365755&partnerID=8YFLogxK
U2 - 10.3390/nano9091298
DO - 10.3390/nano9091298
M3 - Artículo
C2 - 31514340
AN - SCOPUS:85073365755
SN - 2079-4991
VL - 9
JO - Nanomaterials
JF - Nanomaterials
IS - 9
M1 - 1298
ER -