Study of aluminum-doped zinc oxide powders using x-ray diffraction

Zinc oxide has been proposed as a material for next generation gas sensors. In this study, aluminum-doped zinc oxide powders were synthesized via sol gel chemistry using zinc acetate, aluminum tri-tert butoxide and aluminum acetylacetonate precursors. The aluminum-to-zinc ratio in the zinc oxide powders ranged from 0-5\%. The powders were calcined at temperatures from 300$^{\circ}$C to 700$^{\circ}$C, and their mean crystallite sizes were analyzed using x-ray diffraction. A maximum in mean crystallite size was observed at $\approx$0.25-1\% aluminum, the same composition region for which other researchers have reported a maximum in electrical conductivity. It is also found that adding high amounts ($>$2\% Al:Zn ratio) of aluminum to the zinc oxide can retard sintering at higher temperatures.