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.