Formation of tungsten oxide nanostructures by laser pyrolysis: stars, fibres and spheres
1 CSIR National Laser Centre, P. O. Box 395, Pretoria 0001, South Africa
2 School of Physics, University of the Witwatersrand, Private Bag 3, P. O. Wits 2050, Johannesburg, South Africa
3 iThemba Labs, Private Bag 11, Wits 2050, Jan Smuts and Empire Road, Johannesburg, South Africa
4 School of Physics, University of KwaZulu-Natal, Private Bag X54001, Durban 4000, South Africa
Nanoscale Research Letters 2011, 6:166 doi:10.1186/1556-276X-6-166Published: 23 February 2011
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.