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Formation of tungsten oxide nanostructures by laser pyrolysis: stars, fibres and spheres.

Govender M, Shikwambana L, Mwakikunga BW, Sideras-Haddad E, Erasmus RM, Forbes A - Nanoscale Res Lett (2011)

Bottom Line: In this letter, the production of multi-phase WO3 and WO3-x (where x could vary between 0.1 and 0.3) nanostructures synthesized by CO2-laser pyrolysis technique at varying laser wavelengths (9.22-10.82 mm) and power densities (17-110 W/cm2) is reported.The average spherical particle sizes for the wavelength variation samples ranged between 113 and 560 nm, and the average spherical particle sizes for power density variation samples ranged between 108 and 205 nm.It was found that more concentrated starting precursors result in the growth of hierarchical structures such as stars, whereas dilute starting precursors result in the growth of simpler structures such as wires.

View Article: PubMed Central - HTML - PubMed

Affiliation: CSIR National Laser Centre, P, O, Box 395, Pretoria 0001, South Africa. BMwakikunga@csir.co.za.

ABSTRACT
In this letter, the production of multi-phase WO3 and WO3-x (where x could vary between 0.1 and 0.3) nanostructures synthesized by CO2-laser pyrolysis technique at varying laser wavelengths (9.22-10.82 mm) and power densities (17-110 W/cm2) is reported. The average spherical particle sizes for the wavelength variation samples ranged between 113 and 560 nm, and the average spherical particle sizes for power density variation samples ranged between 108 and 205 nm. Synthesis of W18O49 (= WO2.72) stars by this method is reported for the first time at a power density and wavelength of 2.2 kW/cm2 and 10.6 μm, respectively. It was found that more concentrated starting precursors result in the growth of hierarchical structures such as stars, whereas dilute starting precursors result in the growth of simpler structures such as wires.

No MeSH data available.


Related in: MedlinePlus

The comparison of the FTIR transmittance spectrum of the tungsten ethoxide precursor and the CO2 laser radiation absorbance data of tungsten ethoxide as a function of wavelength.
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Figure 4: The comparison of the FTIR transmittance spectrum of the tungsten ethoxide precursor and the CO2 laser radiation absorbance data of tungsten ethoxide as a function of wavelength.

Mentions: Figure 4 shows the absorbance by the precursor as a function of wavelength with the corresponding part of the FTIR transmission spectrum of tungsten ethoxide. This determination gives us an idea if the laser pyrolysis mechanism is a resonant process or if the precursor is decomposed by collisions with excited photosensitizer molecules. However, the results indicate that the laser energy gets transferred to the precursor and should cause decomposition by a resonant process, thus leading to the formation of the predicted products. Therefore, acetylene probably provides a reducing atmosphere in the laser-precursor interaction that influences the reaction pathway towards the formation of the products.


Formation of tungsten oxide nanostructures by laser pyrolysis: stars, fibres and spheres.

Govender M, Shikwambana L, Mwakikunga BW, Sideras-Haddad E, Erasmus RM, Forbes A - Nanoscale Res Lett (2011)

The comparison of the FTIR transmittance spectrum of the tungsten ethoxide precursor and the CO2 laser radiation absorbance data of tungsten ethoxide as a function of wavelength.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211218&req=5

Figure 4: The comparison of the FTIR transmittance spectrum of the tungsten ethoxide precursor and the CO2 laser radiation absorbance data of tungsten ethoxide as a function of wavelength.
Mentions: Figure 4 shows the absorbance by the precursor as a function of wavelength with the corresponding part of the FTIR transmission spectrum of tungsten ethoxide. This determination gives us an idea if the laser pyrolysis mechanism is a resonant process or if the precursor is decomposed by collisions with excited photosensitizer molecules. However, the results indicate that the laser energy gets transferred to the precursor and should cause decomposition by a resonant process, thus leading to the formation of the predicted products. Therefore, acetylene probably provides a reducing atmosphere in the laser-precursor interaction that influences the reaction pathway towards the formation of the products.

Bottom Line: In this letter, the production of multi-phase WO3 and WO3-x (where x could vary between 0.1 and 0.3) nanostructures synthesized by CO2-laser pyrolysis technique at varying laser wavelengths (9.22-10.82 mm) and power densities (17-110 W/cm2) is reported.The average spherical particle sizes for the wavelength variation samples ranged between 113 and 560 nm, and the average spherical particle sizes for power density variation samples ranged between 108 and 205 nm.It was found that more concentrated starting precursors result in the growth of hierarchical structures such as stars, whereas dilute starting precursors result in the growth of simpler structures such as wires.

View Article: PubMed Central - HTML - PubMed

Affiliation: CSIR National Laser Centre, P, O, Box 395, Pretoria 0001, South Africa. BMwakikunga@csir.co.za.

ABSTRACT
In this letter, the production of multi-phase WO3 and WO3-x (where x could vary between 0.1 and 0.3) nanostructures synthesized by CO2-laser pyrolysis technique at varying laser wavelengths (9.22-10.82 mm) and power densities (17-110 W/cm2) is reported. The average spherical particle sizes for the wavelength variation samples ranged between 113 and 560 nm, and the average spherical particle sizes for power density variation samples ranged between 108 and 205 nm. Synthesis of W18O49 (= WO2.72) stars by this method is reported for the first time at a power density and wavelength of 2.2 kW/cm2 and 10.6 μm, respectively. It was found that more concentrated starting precursors result in the growth of hierarchical structures such as stars, whereas dilute starting precursors result in the growth of simpler structures such as wires.

No MeSH data available.


Related in: MedlinePlus