Preparation and sintering of nanocrystalline ITO powders with different SnO₂ content

The effect of SnO₂ content on the sintering behavior of nanocrystalline indium tin oxide (ITO) ceramics was examined. Nanocrystalline ITO powders with different SnO₂ content from 0 to 12 at.% were prepared by a coprecipitation method. The particle size of the ITO powders was in the range of 20-26 nm. The temperature that showed maximum densification increased as the content of SnO₂ increased. Since the solubility limit of SnO₂ in In₂O₃ is known to be about 6-8 at.%, the samples with 8 and 12 at.% Sn showed second phases after sintering. Various phase development processes of the second phases were observed, i.e., In₂SnO₅, which was observed at a low temperature, decomposed into In₂O₃ and SnO₂ at over 1000 °C, then synthesized again into In₄Sn₃O₁₂ at over 1300 °C. The densification behavior with respect to the SnO₂ content was explained from a viewpoint of the second phase development at different sintering temperatures.