Optimising the formation of WO3

We report on the production of multi-phase WO3 and WO3-x (where x could vary between 0.2 and 0.33) nanostructures synthesized by CO2-laser pyrolysis technique at varying laser wavelengths (9.22-10.82 μm) and power densities (17-110 W/cm). The average spherical particle sizes for the wavelength variation samples ranged between 113-560 nm and the average spherical particle sizes for the power density variation samples ranged between 108-205 nm. Synthesis of W3O8 (= WO2.67) stars by this method is reported for the first time at a power density and wavelength of 2.2 kW/cm 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.