| In this thesis, the nucleation and aging steps of several traditional preparation methods of hydrotalcite-like materials have been investigated systematically- and a novel synthetic method is reported in which nucleation and aging steps are performed separately. The crystallinity of the product prepared by this new method is higher than that of the product of the traditional routes, the particle size can be readily controlled and the crystallite size distribution is relatively narrow. The mean particle size and size distribution of the hudrotalcite- like materials can be readily controlled by variation of the aging time.In this thesis, the crystal structure of zinc-aluminium double oxides has been investigated. The XRD patterns of zinc oxide, aluminium oxide and their mixture have been studied. The results show that the crystal structure of zinc-aluminium double oxide is similar to that of ZnO but it is not a simple combination of zinc oxide and aluminium oxide. Calcined above 700 for 3hr, zinc-aluminium double oxide can be divided into two parts, ZnO and ZnAl2O4.The ultraviolet absorbing and screening properties and visible light transmittance of zinc-aluminium double oxides has been investigated. It has been found that zinc-aluminium double oxides is more effective than ZnO . magnisium-aluminium double oxide and Zn-AILDH in absorbing and screening ultraviolet radiation and have higher visible light transmittance than ZnO. From 400 to 600, zinc-aluminium double oxides get more effective in absorbing and screening ultraviolet with the increasing calcination temperature. From 700 to 900, the effect get worse with the increasing calcination temperature. |
