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 5D0-7F2 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 5D0-7F2 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 5D0-7F2 increased. In the Y2O3:Eu3+ powders, the Ag shells absorbed the excitation light, leading to the decrease in excitation density and the intensity of 5D0-7F2.