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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

Bearing area analysis for typical individual sol-gel-developed and exfoliated WO3 nanoflakes sintered at 550°C (A) and 650°C (B). Inserts: appropriate AFM images of sol-gel-developed and exfoliated WO3 nanoflakes, respectively.
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Figure 4: Bearing area analysis for typical individual sol-gel-developed and exfoliated WO3 nanoflakes sintered at 550°C (A) and 650°C (B). Inserts: appropriate AFM images of sol-gel-developed and exfoliated WO3 nanoflakes, respectively.

Mentions: It must be taken into account that by using CSFS-AFM, it was possible to analyse not only physical and electrical parameters of the developed Q2D WO3 nanostructures with the thickness of less than 10 nm without damaging them, but also mapping measured parameters to the specific morphology of the analysed WO3 nanoflakes. Furthermore, the great advantage of this approach can be illustrated by bearing analysis, which represents the relative roughness of a surface in terms of high and low areas. The bearing curve is the integral of the surface height histogram and plots the percentage of the surface above a reference plane as a function of the depth of that below the highest point of the image. Figure 4 elaborates bearing analysis performed on Q2D WO3 sintered at 550° and 650°C before and after exfoliation. For the exfoliated Q2D WO3 sintered at 550°C (Figure 4A), it is clearly shown that 90% of Q2D WO3 nanoflakes had an average particle size of less than 20 nm, whereas prior to exfoliation, 90% of the sub-micron WO3 nanostructures comprised flakes with an average particles size of approximately 50 nm. On the other hand, for WO3 nanoflakes sintered at 650°C, the average particles size of sol-gel-developed WO3 prior to exfoliation was ~75 nm (Figure 4B). Following exfoliation, it was possible to decrease the average particles size down to ~42 nm. Bearing analysis has also confirmed that the exfoliation removes larger nanoagglomerations from the surface of WO3 nanostructures and at the same time reduces the thickness of Q2D WO3 nanoflakes. These facts suggested that the sintering temperature of 550°C is more suitable than 650°C for mechanical exfoliation and the development of ultra-thin Q2D β-WO3 nanoflakes.


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)

Bearing area analysis for typical individual sol-gel-developed and exfoliated WO3 nanoflakes sintered at 550°C (A) and 650°C (B). Inserts: appropriate AFM images of sol-gel-developed and exfoliated WO3 nanoflakes, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: Bearing area analysis for typical individual sol-gel-developed and exfoliated WO3 nanoflakes sintered at 550°C (A) and 650°C (B). Inserts: appropriate AFM images of sol-gel-developed and exfoliated WO3 nanoflakes, respectively.
Mentions: It must be taken into account that by using CSFS-AFM, it was possible to analyse not only physical and electrical parameters of the developed Q2D WO3 nanostructures with the thickness of less than 10 nm without damaging them, but also mapping measured parameters to the specific morphology of the analysed WO3 nanoflakes. Furthermore, the great advantage of this approach can be illustrated by bearing analysis, which represents the relative roughness of a surface in terms of high and low areas. The bearing curve is the integral of the surface height histogram and plots the percentage of the surface above a reference plane as a function of the depth of that below the highest point of the image. Figure 4 elaborates bearing analysis performed on Q2D WO3 sintered at 550° and 650°C before and after exfoliation. For the exfoliated Q2D WO3 sintered at 550°C (Figure 4A), it is clearly shown that 90% of Q2D WO3 nanoflakes had an average particle size of less than 20 nm, whereas prior to exfoliation, 90% of the sub-micron WO3 nanostructures comprised flakes with an average particles size of approximately 50 nm. On the other hand, for WO3 nanoflakes sintered at 650°C, the average particles size of sol-gel-developed WO3 prior to exfoliation was ~75 nm (Figure 4B). Following exfoliation, it was possible to decrease the average particles size down to ~42 nm. Bearing analysis has also confirmed that the exfoliation removes larger nanoagglomerations from the surface of WO3 nanostructures and at the same time reduces the thickness of Q2D WO3 nanoflakes. These facts suggested that the sintering temperature of 550°C is more suitable than 650°C for mechanical exfoliation and the development of ultra-thin Q2D β-WO3 nanoflakes.

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