Zinc oxide crystals with controlled size and morphology

Zinc Oxide (ZnO) has been synthesized by evaporation, condensation, and oxidation of metallic Zn under atmospheric pressure, the objective of this study is the growth the particles of ZnO and its relationship with the deposition zone. Pieces of Zn were introduced into a quartz tube acting as reactor which is placed inside the tubefurnace at 920-950°C under controlled pressure and heating profile. Carefully monitoring the temperature zones inside the reactor, ZnO crystals were growth. During heating, the oxygen in the surrounding environment reacted with the Zn pieces' surface to form a ZnO capsule with liquid and gaseous Zn inside. When the pressure inside the capsule surpasses the ambient pressure, cracks are formed in the oxide crust and the Zn vapor is released. Zinc in gaseous state oxidizes as it flows through air, and, depending on its trajectory, a variety of crystallites are obtained with size ranging from 20 nm, for the smallest particles, to 5 μm for the tetrapod nanostructures.