Evolution of the structural properties of sol-gel synthetized ZnO with solid phase and solution-based aluminum dopingat different annealing temperatures.

Abstract

We report here on the effect of aluminum doping and annealing temperature on the structural properties of ZnO, synthetized using the Sol Gel method. Aluminum doping was performed in two ways, either by adding AlCl3 to the Zn solution or by mixing the obtained gel with Alumina prior to the annealing step. It was found that both methods of doping yield very similar results. Aluminum doping does not affect ZnO crystals dimensions for an annealing temperature of 500°C, while it induces a significant reduction in grain size, as well as the appearance of the ZnAl2O4 spinel phase for annealing at 700°C and above.These results suggest that no ZnAl bonds are formed in the solution, when doping with AlCl3. Aluminum doping of ZnO yields a heterogeneous material if annealed at 500°C, while diffusion and subsequent alloy formation occur onlyat higher temperatures.