Ambient pressure syntheses of size-controlled corundum-type In ₂O₃ nanocubes

Hydrolysis of In(O-ⁱPr)₃ by 10 molar excess of water at 90 °C in a surfactant/solvent mixture of oleylamine/oleic acid/trioctylamine provides very small nanoparticles (<5 nm in diameter) of In(O)(OH). Subsequent in situ thermolysis of the formed In(O)(OH) nanoparticles at 350 °C and ambient pressure produces monodisperse h-In₂O₃ nanocubes, which can form an extended two-dimensional array on a flat surface. The size of the In₂O₃ nanocubes (8, 10, and 12 nm) could be easily controlled by the simple change in the amounts of employed surfactants. The h-In₂O₃ nanocube samples show blue PL emissions at room temperature due to, presumably, systematic oxygen vacancy.