Al-doped ZnO powdered materials: Al solubility limit and IR absorption properties

Al-doped ZnO powder was synthesized via the Pechini route with a doping rate varying from 1 to 4 mol.%. A solubility limit has been estimated under 0.3 mol.% of Al using X-ray diffraction refinements. The incorporation of aluminium into the ZnO lattice was investigated by 27Al NMR, which suggests an extremely low amount of Al in a distribution of sites in ZnO. In order to assess the impact of such a low dopant amount, diffuse reflection experiments were performed for a wavelength range from 200 to 2500 nm. If the effect of doping was negligible for samples prepared at 850 similar to C, annealing at 1200 degrees C clearly reveals enhanced IR absorption properties for the doped samples, which are similar whatever be the nominal Al content. (C) 2009 Elsevier Masson SAS. All rights reserved.