University of Technology, Sydney. Faculty of Science.Zinc oxide is an important material industrially and scientifically. It has a long history dating back to more than four thousand years ago. It has applications in rubber production, cosmetics, pigments and ceramics. The properties of zinc oxide such as porosity, specific surface area and optical properties change as a result of changing the synthetic method and process conditions. The suitability of ZnO for different applications depends on the properties of the material, which in turn are influenced by synthetic routes.
Knowledge of the processes underpinning the various synthetic techniques is key to understanding the properties of the ZnO end-product. In this work, various synthetic techniques have been investigated that may be amenable to large-scale production. The resultant materials were studied and important insights were obtained. For example, it was found that the precursor materials and method of processing for the production of zinc oxide have important roles in controlling the properties of the product such as specific surface area, crystal morphology, particle size and amount of surface hydroxyl groups embedded in the product.
In single-stage production methods, zinc oxide is precipitated directly from a zinc solution. Influences of reaction temperature, concentration of the reactants and feeding techniques on the properties of the products were determined.
In multi-stage routes, intermediate zinc-bearing materials including zinc peroxide and zinc hydroxy carbonate, sulphate, chloride, nitrate and acetate were synthesised. These intermediate materials were then used as precursors for the formation of zinc oxide particles. Relationships between the properties of the precursor zinc-containing compound and the end-product zinc oxide were studied and unexpected results were obtained. For example, it was shown that specific surface area of the zinc oxide product depends significantly on the precursor material from which it is produced. Techniques were investigated that can produce multiple important zinc-bearing compounds and it was found that it could be engineered by selection of the appropriate precursors and process conditions