Preparation and optical properties of transparent tellurite based glass ceramics doped by Er3+ and Eu3+

Optically transparent Er3+ and Eu3+ eloped (less than 1.5 mol% Er2O3 and Eu2O3) glass ceramics based on the system K2O-MgO-Nb2O5-TeO2 have been successfully prepared for the first lime. Addition of Er3+ and Eu3+ is effective for the formation of a crystalline phase showing second harmonic generation Fluorescence spectra of Er3+ and Eu3+ in glass ceramics are almost similar to those in precursor glasses. The intensity of frequency upconversion fluorescence at around 550 nm due to the S-4(3l2)-->I-4(I5l2) transition of Er3+ in the glass ceramics is strong compared with that in their precursor glass. From the phonon sideband spectra associated with D-5(2)-->F-7(0) transition of Eu3+ it is found that the phonon energy for transparent glass ceramics is smaller than that in the glasses indicating that the multiphonon relaxation rate of Er3+ and Eu3+ present in TeO2 based glass ceramics is smaller than that in the corresponding TeO2 based glasses. Whether Er3+ and Eu3+ are incorporated into the crystalline phase or not is unclear the present study gives a new possibility, far optical applications of transparent TeO2 based glass ceramics.