Optical and site-selective spectral studies of Eu3+-doped zinc oxyfluorotellurite glass

The Eu3+-doped zinc oxyfluorotellurite (TZLFE) glass of molar composition 59TeO(2)-20ZnO-20LiF-1Eu(2)O(3) has been prepared and studied by broadband, Raman, and fluorescence-line narrowing (FLN) spectral techniques to investigate the local environments of Eu3+ ions in this glass. From the vibronic spectra, different TeO groups coupled to Eu3+ ions have been identified. From the broadband excitation and emission spectra at RT, energy levels of the Eu3+ ion and the atomic parameters have been calculated. The D-5(0) level of Eu3+ ions in the TZLFE glass has been selectively excited within the inhomogeneously broadened F-7(0)-> D-5(0) excitation spectrum at 15 K. The resulting D-5(0)-> F-7(1) fluorescence spectra and the lifetimes of the D-5(0) level have been obtained as a function of the excitation wavelength. From the FLN spectra, three Stark levels have been identified and crystal-field (CF) analysis has been carried out to calculate second rank CF parameters, by assuming C-2v orthorhombic symmetry, as a function of the excitation wavelength. From the CF parameters, CF strength parameter has been calculated. The observed behavior suggests the existence of a unique kind of site for all the environments of Eu3+ ions in the TZLFE glass. The local structure of Eu3+ ions in the TZLFE glass is almost similar to sodium borosilicate glass but with a shorter distribution of environments.