Morphologically controlled synthesis of flower shaped ZnO crystals with hexagonal rods and thick petals by hydrothermal method

•Soluble starch was used for the morphology control of ZnO structures by hydrothermal method.•In the absence of soluble starch flower-like ZnO structures with hexagonal rods were obtained.•The hexagonal rods of the ZnO flower transformed into six thick petals around a well defined center in the presence of soluble starch.

Specific flower shaped ZnO crystals with well defined morphologies have been synthesized via hydrothermal method using zinc acetate dihydrate and sodium hydroxide as starting materials. Also soluble starch was used as a stabilizer and crystallization controller in alkaline medium. Scanning electron microscopy studies suggested that keeping all experimental parameters constant the morphology of ZnO crystals could be easily changed in the presence of starch. The analyses of the crystal structures and the morphologies of flower shaped ZnO were carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with EDS. A mechanism for the formation of different morphologies is proposed.