Enhanced visible emission in Eu3+ doped glass containing Ag-clusters, Ag nanoparticles, and ZnO nanocrystals

We report the formation of ZnO nanocrystals, Ag-clusters, and Ag nanoparticles in Eu-doped borate glasses by furnace annealing and CO2 laser annealing. The XRD and optical properties of the samples obtained with two techniques were analyzed and compared to each other. The absorption spectra of the samples presented surface plasmon bands centered at 430 nm associated with nanoparticles. The EDS image revealed the incorporation of rare-earth ions into ZnO nanocrystal. The overall down-conversion blue-green emission intensity obtained with 365 nm excitation was enhanced by 70 times in the glass treated by the CO2 laser, mainly due to the Ag-cluster formation. These results indicate the possibility of the development of a more efficient and spatially selective display in the glass host. The yellow-red emission enhancement of Eu3+ ions was explained by energy transfer from the Ag-nanoclusters to Eu3+ ions, as well as the crystalline environment due to ZnO nanocrystal formation. Up-conversion emissions of the Eu3+ ions under 980 nm excitation were enhanced with thermal treatments due to the incorporation of Eu3+ ions in ZnO nanocrystals. Energy transfer between the Ag species and Eu3+ ions is discussed so as to explain the emission properties. (C) 2019 Elsevier B.V. All rights reserved.