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Enhanced electrical properties in sub-10-nm WO3 nanoflakes prepared via a two-step sol-gel-exfoliation method.

Zhuiykov S, Kats E - Nanoscale Res Lett (2014)

Bottom Line: The morphology and electrical properties of orthorhombic β-WO3 nanoflakes with thickness of ~7 to 9 nm were investigated at the nanoscale with a combination of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), current sensing force spectroscopy atomic force microscopy (CSFS-AFM, or PeakForce TUNA™), Fourier transform infra-red absorption spectroscopy (FTIR), linear sweep voltammetry (LSV) and Raman spectroscopy techniques.CSFS-AFM analysis established good correlation between the topography of the developed nanostructures and various features of WO3 nanoflakes synthesized via a two-step sol-gel-exfoliation method.It was determined that β-WO3 nanoflakes annealed at 550°C possess distinguished and exceptional thickness-dependent properties in comparison with the bulk, micro and nanostructured WO3 synthesized at alternative temperatures.

View Article: PubMed Central - HTML - PubMed

Affiliation: Materials Science and Engineering Division, CSIRO, 37 Graham Road, Highett, VIC 3190, Australia.

ABSTRACT
The morphology and electrical properties of orthorhombic β-WO3 nanoflakes with thickness of ~7 to 9 nm were investigated at the nanoscale with a combination of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), current sensing force spectroscopy atomic force microscopy (CSFS-AFM, or PeakForce TUNA™), Fourier transform infra-red absorption spectroscopy (FTIR), linear sweep voltammetry (LSV) and Raman spectroscopy techniques. CSFS-AFM analysis established good correlation between the topography of the developed nanostructures and various features of WO3 nanoflakes synthesized via a two-step sol-gel-exfoliation method. It was determined that β-WO3 nanoflakes annealed at 550°C possess distinguished and exceptional thickness-dependent properties in comparison with the bulk, micro and nanostructured WO3 synthesized at alternative temperatures.

No MeSH data available.


Related in: MedlinePlus

Raman spectra (perturbation region within 600 to 1,000 cm-1) for sol-gel-developed WO3 and exfoliated Q2D WO3 nanoflakes. Sintered at 550°C (A) and 650°C (B), respectively.
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Figure 7: Raman spectra (perturbation region within 600 to 1,000 cm-1) for sol-gel-developed WO3 and exfoliated Q2D WO3 nanoflakes. Sintered at 550°C (A) and 650°C (B), respectively.

Mentions: Raman spectroscopy was employed to determine the vibration and rotation information in relation to chemical bonds and symmetry of molecules in sol-gel-developed WO3, sintered at 550° and 650°C, respectively, and exfoliated ultra-thin Q2D WO3. Raman spectra for sol-gel-developed WO3 and exfoliated Q2D WO3 nanoflakes in the perturbation area of the spectrum are shown in Figure 7. In both cases, Raman peaks corresponding to WO3 were observed. The bending modes of WO3 are usually located between 600 and 900 cm-1, while the stretching modes can be observed between 200 and 500 cm-1[41]. The prominent band situated at 802 cm-1 has been assigned to the symmetric stretching mode of terminal (W6+ = O) groups which may also be vibrationally coupled [42]. This peak represents lattice discontinuities which lead to short-range (lattice) order. The presence of O-W-O bond is typically associated with β-WO3[43]. There were no other substantial peaks noted, suggesting that no impurities were present in the samples. Bridging (O-W-O) vibrations, which occur around 700 cm-1, are influenced significantly by hydration [30], and as a result, the recorded 712 cm-1 band can be used as a spectral marker for hydration level of WO3[44]. However, care should be exercised using this approach, since the crystalline hexagonal phase (h-WO3) also exhibits bands at these frequencies but is likely to be absent in sample prepared without a thermal annealing step.


Enhanced electrical properties in sub-10-nm WO3 nanoflakes prepared via a two-step sol-gel-exfoliation method.

Zhuiykov S, Kats E - Nanoscale Res Lett (2014)

Raman spectra (perturbation region within 600 to 1,000 cm-1) for sol-gel-developed WO3 and exfoliated Q2D WO3 nanoflakes. Sintered at 550°C (A) and 650°C (B), respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4150682&req=5

Figure 7: Raman spectra (perturbation region within 600 to 1,000 cm-1) for sol-gel-developed WO3 and exfoliated Q2D WO3 nanoflakes. Sintered at 550°C (A) and 650°C (B), respectively.
Mentions: Raman spectroscopy was employed to determine the vibration and rotation information in relation to chemical bonds and symmetry of molecules in sol-gel-developed WO3, sintered at 550° and 650°C, respectively, and exfoliated ultra-thin Q2D WO3. Raman spectra for sol-gel-developed WO3 and exfoliated Q2D WO3 nanoflakes in the perturbation area of the spectrum are shown in Figure 7. In both cases, Raman peaks corresponding to WO3 were observed. The bending modes of WO3 are usually located between 600 and 900 cm-1, while the stretching modes can be observed between 200 and 500 cm-1[41]. The prominent band situated at 802 cm-1 has been assigned to the symmetric stretching mode of terminal (W6+ = O) groups which may also be vibrationally coupled [42]. This peak represents lattice discontinuities which lead to short-range (lattice) order. The presence of O-W-O bond is typically associated with β-WO3[43]. There were no other substantial peaks noted, suggesting that no impurities were present in the samples. Bridging (O-W-O) vibrations, which occur around 700 cm-1, are influenced significantly by hydration [30], and as a result, the recorded 712 cm-1 band can be used as a spectral marker for hydration level of WO3[44]. However, care should be exercised using this approach, since the crystalline hexagonal phase (h-WO3) also exhibits bands at these frequencies but is likely to be absent in sample prepared without a thermal annealing step.

Bottom Line: The morphology and electrical properties of orthorhombic β-WO3 nanoflakes with thickness of ~7 to 9 nm were investigated at the nanoscale with a combination of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), current sensing force spectroscopy atomic force microscopy (CSFS-AFM, or PeakForce TUNA™), Fourier transform infra-red absorption spectroscopy (FTIR), linear sweep voltammetry (LSV) and Raman spectroscopy techniques.CSFS-AFM analysis established good correlation between the topography of the developed nanostructures and various features of WO3 nanoflakes synthesized via a two-step sol-gel-exfoliation method.It was determined that β-WO3 nanoflakes annealed at 550°C possess distinguished and exceptional thickness-dependent properties in comparison with the bulk, micro and nanostructured WO3 synthesized at alternative temperatures.

View Article: PubMed Central - HTML - PubMed

Affiliation: Materials Science and Engineering Division, CSIRO, 37 Graham Road, Highett, VIC 3190, Australia.

ABSTRACT
The morphology and electrical properties of orthorhombic β-WO3 nanoflakes with thickness of ~7 to 9 nm were investigated at the nanoscale with a combination of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), current sensing force spectroscopy atomic force microscopy (CSFS-AFM, or PeakForce TUNA™), Fourier transform infra-red absorption spectroscopy (FTIR), linear sweep voltammetry (LSV) and Raman spectroscopy techniques. CSFS-AFM analysis established good correlation between the topography of the developed nanostructures and various features of WO3 nanoflakes synthesized via a two-step sol-gel-exfoliation method. It was determined that β-WO3 nanoflakes annealed at 550°C possess distinguished and exceptional thickness-dependent properties in comparison with the bulk, micro and nanostructured WO3 synthesized at alternative temperatures.

No MeSH data available.


Related in: MedlinePlus