Optical spectroscopy of Eu3+ doped zinc borate glasses

Abstract

Zinc borate binary glasses of composition 4ZnO.3B2O3 undoped and doped with 0.5% mol of Eu3+ were prepared from the melt giving rise to samples of excellent optical quality. In the present work we use the spectroscopic properties of the Eu3+ to obtain information about the structural and dynamic features of our system. Different optical techniques such as site selection, excitation spectroscopy and lifetime measurements as well as Raman spectroscopy were used to study the local environment of the Eu3+ ion in these glasses. No energy transfer is observed at our concentration and moreover non-radiative relaxation from the excited 5D0 state to the 7Fj manifold is not important. A broad distribution of slightly different environments of the Eu3+ ion is reflected in the trend of the Stark splittings of the 7F1 state and in the crystal field parameters for the individual sites as a function of the excitation wavelength. Phonon sidebands are observed in the excitation and luminescence spectra of the Eu3+ impurity. We make an attempt to assign these sidebands to coupling of the vibrational modes of the structural units containing the Eu3+ ion. The strength of the electron-phonon coupling is evaluated and compared with the result obtained for related systems.