Oxygen partial pressure effect on the preparation of nanocrystalline tungsten oxide powders by a plasma arc gas condensation technique

In the present study, nanocrystalline tungsten oxide powders were prepared by a plasma arc gas condensation technique under a controlled oxygen environment with Ar/O2 ratio ranged from 1/1 to 100/1. It is noted that stoichiometric tungsten oxide nanocrystalline powders (WO3) can be prepared under an Ar/O2 ratio ranged from 1/1 to 99/1, while nonstoichiometric tungsten oxide nanopowders (WO3-x) were synthesized under an Ar/O2 ratio of 100/1. The as-prepared WO3 powders were examined by X-ray diffraction (XRD), Raman scattering, thermal gravimetric analysis (TGA), and high-resolution transmission electron microscope (HRTEM). Experimental results showed that yellowish WO3 nanopowders prepared using different Ar/O2 ratio exhibited slight differences.