The luminescence properties of the ZnO@ZnWO4:Eu3+ core-shell composites

The ZnO@ZnWO4:Eu3+ core-shell composites were prepared by a two-step hydrothermal method and the photoluminescence properties of the composites were studied in contrast to the corresponding hexagonal ZnO and monoclinic ZnWO4: Eu3+ nanocrystals prepared by the one-step hydrothermal method. The results demonstrate that in the nanocomposites the Eu3+ ions in the ZnWO4 phase occupy two symmetry sites, one a well-crystalline inner site and one a disordered surface site; while in the ZnWO4: Eu3+ nanocrystals, the local environments surrounding Eu3+ ions are relatively disordered for both the inner and the surface sites. This indicates that in the composites, the crystallinity of the ZnWO4 becomes better, which have positive influence on the improvement of photoluminescence. The temperature stabilities for both the emissions of ZnO and Eu3+ ions are improved in contrast to the pure ZnO or ZnWO4:Eu3+ nanocrystals. (c) 2007 Elsevier B.V. All rights reserved.