2012 年 22 巻 2 号 p. 129-134
Indium tin oxide (ITO) nanoparticles have been synthesized from the mixed ethylene glycol solution of indium (III) chloride, tin (II) chloride and sodium hydroxide by the solvothermal process with the addition of oleylamine or oleic acid as a protective reagent. The x-ray diffraction patterns of particles synthesized at 250°C show that the ITO begins to be produced after the reaction duration of 6 h when oleylamine is added to the reaction solution, indicating a promoting effect on the ITO formation, whereas only indium oxyhydroxide is formed when oleic acid is used. The transmission electron microscopic observation has revealed that ITO nanoparticles obtained by the addition of oleylamine are monodisperse and their size increases from 4-5 nm to 50-60 nm with elongating reaction duration from 6 to 96 h. ITO thin films are prepared by the multiple deposition of a collodion membrane incorporating synthesized ITO nanoparticles on the glass substrate followed by sintering at 400-500°C. They exhibit a good transparency in the visible region and a specific resistivity as low as 1.0 Ω·cm.