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

In this letter, the production of multi-phase WO(3 )and WO(3-)(x )(where x could vary between 0.1 and 0.3) nanostructures synthesized by CO(2)-laser pyrolysis technique at varying laser wavelengths (9.22-10.82 mm) and power densities (17-110 W/cm(2)) 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 W(18)O(49 )(= WO(2.72)) stars by this method is reported for the first time at a power density and wavelength of 2.2 kW/cm(2 )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.