Limits...
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

SEM images of the nanostructured WO3 nanostructures obtained by sol-gel process. Annealed at 550°C (A), 650°C (B), 700°C (C), 750°C (D) and 800°C (E), respectively. EDX analysis for WO3 annealed at 550°C (F).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4150682&req=5

Figure 1: SEM images of the nanostructured WO3 nanostructures obtained by sol-gel process. Annealed at 550°C (A), 650°C (B), 700°C (C), 750°C (D) and 800°C (E), respectively. EDX analysis for WO3 annealed at 550°C (F).

Mentions: Figure 1 displays SEM images of the sol-gel-developed WO3 on Au- and Cr-coated Si substrates, which were sintered at different temperatures. Micrographs of the deposited WO3 thin-films revealed the effect of the annealing temperature on the surface morphology. As shown in Figure 1A, the majority of WO3 nanoflakes annealed at 550°C were in the range of 20 to 50 nm in length with few larger nanoflakes of ~100 nm. However, as the annealing temperature increased, the morphology of WO3 nanoflakes also changed and the average size of the sintered WO3 nanoflakes increased (Figure 1B,C,D). For instance, at the sintering temperature of 750°C, the average size of WO3 nanoflakes was ~100 to 150 nm. The increase in the sintering temperature seems to have enabled the growth of lager nanoflakes. A further increase in the annealing temperature up to 800°C led to the growth of WO3 nanoflakes with average size of ~200 to 400 nm (Figure 1E). This was mainly due to agglomeration of the sintered nanoparticles to form larger crystallites; some of them were larger than 0.5 μm in diameter. The SEM results obtained were in good correlation with independently published results [31]. Subsequent EDX analysis of all the sintered WO3 nanostructures confirmed that they comprise a single crystalline phase without impurities. The peaks were narrow with high intensity exhibiting high crystallinity of the developed WO3 nanoflakes (Figure 1F). The results of the mechanical exfoliation of all the synthesized WO3 nanostructures revealed that it was possible to exfoliate Q2D WO3 nanoflakes annealed only at 550° and 650°C, respectively. Higher sintering temperatures ensured the development of strong bonds between adjacent WO3 layers preventing exfoliation. Therefore, all other experiments were carried out only on WO3 nanoflakes sintered at 550° and 650°C.


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)

SEM images of the nanostructured WO3 nanostructures obtained by sol-gel process. Annealed at 550°C (A), 650°C (B), 700°C (C), 750°C (D) and 800°C (E), respectively. EDX analysis for WO3 annealed at 550°C (F).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: SEM images of the nanostructured WO3 nanostructures obtained by sol-gel process. Annealed at 550°C (A), 650°C (B), 700°C (C), 750°C (D) and 800°C (E), respectively. EDX analysis for WO3 annealed at 550°C (F).
Mentions: Figure 1 displays SEM images of the sol-gel-developed WO3 on Au- and Cr-coated Si substrates, which were sintered at different temperatures. Micrographs of the deposited WO3 thin-films revealed the effect of the annealing temperature on the surface morphology. As shown in Figure 1A, the majority of WO3 nanoflakes annealed at 550°C were in the range of 20 to 50 nm in length with few larger nanoflakes of ~100 nm. However, as the annealing temperature increased, the morphology of WO3 nanoflakes also changed and the average size of the sintered WO3 nanoflakes increased (Figure 1B,C,D). For instance, at the sintering temperature of 750°C, the average size of WO3 nanoflakes was ~100 to 150 nm. The increase in the sintering temperature seems to have enabled the growth of lager nanoflakes. A further increase in the annealing temperature up to 800°C led to the growth of WO3 nanoflakes with average size of ~200 to 400 nm (Figure 1E). This was mainly due to agglomeration of the sintered nanoparticles to form larger crystallites; some of them were larger than 0.5 μm in diameter. The SEM results obtained were in good correlation with independently published results [31]. Subsequent EDX analysis of all the sintered WO3 nanostructures confirmed that they comprise a single crystalline phase without impurities. The peaks were narrow with high intensity exhibiting high crystallinity of the developed WO3 nanoflakes (Figure 1F). The results of the mechanical exfoliation of all the synthesized WO3 nanostructures revealed that it was possible to exfoliate Q2D WO3 nanoflakes annealed only at 550° and 650°C, respectively. Higher sintering temperatures ensured the development of strong bonds between adjacent WO3 layers preventing exfoliation. Therefore, all other experiments were carried out only on WO3 nanoflakes sintered at 550° and 650°C.

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