Nonaqueous Synthesis of Nanocrystalline Indium Oxide and Zinc Oxide in the Oxygen-Free Solvent Acetonitrile

The nonaqueous preparation of nanocrystalline indium and zinc oxide involving the solvothermal reaction of metal acetylacetonates with acetonitrile is presented. The synthesis approach is characterized by a particularly moderate reaction temperature of 100 °C and by the use of an oxygen-free solvent. The oxygen for the metal oxide formation is supplied by the acetylacetonate ligand of the precursor molecules. In the case of In 2 O 3, the product consists of crystalline nanoparticles with a spherical morphology and a narrow size distribution in the range of 3−6 nm. According to transmission electron microscopy (TEM), the ZnO nanoparticles are in the size range of 15−85 nm, sometimes with well-faceted hexagonal morphology. Powder X-ray diffraction (XRD) data as well as high-resolution TEM point to mesocrystal formation, i.e., the ZnO nanoparticles are composed of a highly oriented arrangement of smaller nanocrystallites that scatter like a single crystal.