The Luminescence Properties of ZnO:Al Nanopowders Obtained by Sol-gel, Plasma and Vaporization-Condensation Methods

ZnO nanocrystals were synthesized and characterized by XRD and SEM methods. The luminescence spectra and decay kinetics were studied under pulsed laser excitation (266 nm, 8 ns). ZnO and ZnO:Al powders were prepared by sol-gel and plasma chemical synthesis. These powders were used as a raw material for the SPVD (Solar Physical Vapour Deposition) process. In this way, the vaporisation-condensation phenomenon (VC) led to the formation of ZnO whiskers and nanopowders. The luminescence properties of the VC nanopowders were studied and compared to those displayed by the raw material. The Al dopant, present in the raw powders as a solid solution and ZnAl2O4 precipitates, was only present as Al ions in the nanopowders after the SPVD. The blue luminescence intensity increased considerably after SPVD. The whiskers type microstructures showed nonlinear blue luminescence dependent on the excitation pulse density.