Synthesis and optical properties of nanometer to micrometer wide hexagonal cones and columns of ZnO

Hexagonal cones and columns of ZnO were synthesized by solvothermal process with their diameters ranging from the nanometer to micrometer scale. All the nano/micro structures were perfectly single crystalline. Morphological control over the products was achieved by varying the composition of the ethanol–water system used as the solvent as well as its pH level. The ZnO nano/micro crystals were found to have wurtzite crystal structure. The optical absorbance and photoluminescence spectra of all the samples showed excitonic character at room temperature indicating excellent crystal quality of the products.