MORPHOLOGY AND GROWTH-MECHANISM OF ZNO PARTICLES ELECTRO-CRYSTALLIZEDON ZN IN AQUEOUS-SOLUTION

Products made by the electrochemical reaction of 500 mu m thick Zn she ets and 25 mu m thick Zn foils with distilled water at 20 degrees C ar e investigated by scanning electron microscopy. X-ray diffraction, and pH measurements of the water. The reaction goes through the following processes: (A) the formation of formless ZnO layers: (B) the growth o f spindle-like ZnO particles and the precipitation of octahedral beta- Zn(OH)(2) particles, with increasing pH (Max = 8.4) that is caused by the dissolution of the ZnO; and (C) the reduction of spindle growth wi th decreasing pH, caused by the precipitation of Zn(OH)(2). The proces ses are repeated, and the reaction ceases when the metal is completely consumed. These cyclic processes appear as peaks in the pH/time-depen dence curve.