Fundamental study of Ti feedstock evaporation and the precursor formation process in inductively coupled thermal plasmas during TiO2 nanopowder synthesis

摘要

Two-dimensional spectroscopic observations were conducted for an inductively coupled thermal plasma (ICTP) torch during TiO2 nanopowder synthesis. The feedstock was injected intermittently into the ICTP torch to investigate the Ti feedstock evaporation process clearly and to elucidate the formation process of precursor species. Spatiotemporal distributions of Ti atomic lines and TiO spectra were observed simultaneously inside the plasma torch with the observation system developed. The observation results showed that the injected Ti feedstock was evaporated to form high-density Ti atomic vapour in the torch, and that the generated Ti atomic vapour is transported and diffused by gas flow and the density gradient. In addition, TiO molecular vapour was generated almost simultaneously around the on-axis region in the torch.