Preparation and optical properties of Ag enwrapped Y2O3:Eu3+ nanoparticles in solution and in powders

Ag enwrapped Y2O3:Eu3+ nanoparticles were prepared by a wet chemistry method, which was dispersed in liquid (glycol) or dried to powders. Their luminescence properties were studied in comparison to those in the un-enwrapped ones. The results demonstrated that in glycol the D-5(0)-F-7(2) transitions for Ag enwrapped Y2O3:EU3+ nanoparticles became stronger than that for un-enwrapped ones, while the excitation charge transfer band shifted blue. On the contrary, the D-5(0)-F-7(2) transitions in Ag enwrapped Y2O3:EU3+ powders became weaker than those in the un-enwrapped ones. It was suggested that in liquid the Ag shells thinly deposited in the surface Of Y2O3:Eu3+ and insulated the Y2O3:Eu3+ from the liquid, which contained large organic vibration modes. As a result, the surface nonradiative energy transfer from Eu3+ to the organic modes decreased, and emission intensity of D-5(0)-F-7(2) increased. In the Y2O3:EU3+ powders, the Ag shells absorbed the excitation light, leading to the decrease in excitation density and the intensity of D-5(0)-F-7(2). (c) 2005 Elsevier Ltd. All rights reserved.