Preparation of indium tin oxide (ITO) nanoparticles by DC arc plasma

Tin-doped indium oxide (ITO) nanoparticles were prepared by DC arc plasma. The mixture of In(OH)₃ and SnCl₂ as precursors was injected into the arc plasma through a powder feeder and vaporized by the arc plasma. The ITO nanoparticles were synthesized through the rapid quenching of the thermal plasma processing and did not require post-treatment. The doped level of the synthesized particles was controlled by varying the molar ratio of SnCl₂ in the powder feeder. The obtained nanoparticles were characterized by X-ray diffractometer (XRD), inductively coupled plasma optical emission spectroscopy (ICP-OES), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-Vis spectroscopy and four-probe analysis. The XRD results showed a shift of the peak, a broadening of the peak width and the decrease of the peak intensity as the doping level increased. The doping amount of tin was analyzed by ICP-OES. XPS results presented that most of the tin was incorporated into the indium oxide lattice without the formation of any tin oxide. The particle size ranged from 5nm to 25nm. The faceted morphologies of the prepared ITO nanoparticles could be observed using TEM. Additionally, the transmittances and the electrical conductivities of the prepared ITO were measured to evaluate the properties as a transparent conductive oxide.