Sol-gel synthesis and characterization of nanocrystalline ZnO powders

Nanocrystalline zinc oxide (ZnO) powders were prepared by fast hydrolysis of zinc 2-ethylhexanoate dissolved in 2-propanol, adding a tetramethylammonium (TMAH) aqueous solution. XRD showed an average value of 25-35 nm for the basal diameter of supposed cylinder (prism)-shaped crystallites, whereas the height of these crystallites was 35-45 nm. TEM showed that the size of the majority of ZnO particles varied between 20 and 50 nm, thus indicating that particle and crystallite sizes in ZnO powders were approximately equal. The size of ZnO particles did not change significantly for different amounts of zinc 2-ethylhexanoate in the precipitation systems investigated. Raman spectra of ZnO particles were interpreted taking into account the nanosize effect.