Effects of Sb oxidation state on the densification and electrical properties of antimony-doped tin oxide ceramics

For antimony-doped tin oxide (ATO), Sb content and oxidation state remarkably influence the densification, microstructure and electrical properties of ATO ceramics. In this work, ATO powders doped with Sb(III) or Sb(V) are prepared via chemical precipitation method and are then consolidated by spark plasma sintering (SPS). Results demonstrate that ATO ceramics with a small content of nanoscaled antimony oxides, either Sb(III) or Sb(V), can be densified through the rapid SPS process. The relative density of 1.5 mol% Sb-doped samples is greater than 96.5 %. However, increased Sb doping concentration, especially for Sb(V), restrains both the densification and grain growth in SPS-consolidated ATO. In contrast, Sb(V)-doped material exhibits improved electrical conductivity. The resistivity of 1.5 mol% Sb(V)-doped sample is only 0.01699 Omega cm, far lower than that of the 1.5 mol% Sb(III)-doped sample (0.1338 Omega cm). XPS results indicate a higher Sb5+/Sb3+ ratio in Sb(V)-doped ATO powder and ceramic than in Sb(III)-doped samples. The higher Sb5+/Sb3+ ratio contributes to the increase of carrier concentration and the decrease of resistivity of ATO ceramics.