Preparation of Nano-sized Indium Tin Oxide (ITO) Powders and Their Sintering Behavior

Abstract

In order to fabricate a high density sintered body of ITO, nano-sized ITO powders were synthesized by coprecipitation methods. Aqueous solutions of indium and tin salts were mixed and coprecipitated by changing their pH. Coprecipitated ITO powders possessed 20-30 nm crystallite size and a relatively high BET value (35 m2/g), however, aggregation of particles were occurred. Therefore, a novel recrystallization technique was applied in order to eliminate the aggregates. The recrystallized ITO material consists of a little bit larger needlelike crystals, 20 nm × 80 nm, and it possesses a higher BET value (57 m2/g) compared to the plain coprecipitated material (35 m2/g). Metastable phase formation and higher content of aggregated particles were observed in the coprecipitated materials. Densification was 95% to 98% complete after 5 hour sintering at 1500℃ for the recrystallized powders while densities of the coprecipitated powders were below 75%.