Influence of composition, doping concentration and annealing temperatures on optical properties of Eu3+-doped ZnO-SiO2 nanocomposites
We have stupied structure and optical properties of ZnO - SiO2 nanocomposites doped with Eu3+ ions with varied concentrations of ZnO and the annealing temperatures. The thin films containing ZnO - SiO2 nanocomposites doped Eu3+ ions were preparedby sol – gel method and spin-coating process. The stuctures and morphologies of the thin films are studied by X- ray diffraction ( XDR) and scanning electron microsope (SEM). SEM images and X- ray diffraction patterns indicate that ZnO nanocrystals were creatin SiO2 matrix with particle size of about 3- 5 nm. In addition, the emission and excitation spectra were studies. From the analysis of the optical data, we are able to demontrate that multiple Eu- related optical centers are present in the studied samples. The dominating of 5D0 – 7F2 transition of Eu3+ ions at about 613 nm suggests that Eu3+ ions mainly take a site with inversion antisymmetry in the ZnO host. Also, the energy transfer from ZnO nanocsystals ta Eu3+ ions are observed in the excitation spectra with the excitation wavelengths ranging from 250 nm to 450 nm.