Energy transfer induced Eu3+ photoluminescence enhancement in tellurite glass

In this work, structural, thermal and optical properties of Eu3+ doped TeO2-La2O3-TiO2 glass were investigated. The differential scanning calorimetry (DSC) measurements reveal an important stability factor Delta T= 143.52 K, which indicates the good thermal and mechanical stabilities of tellurite glass. From the absorption spectrum, the optical band gap was found to be direct with E-g=3.23 eV. The temperature dependences of photoluminescence (PL) properties of Eu-doped and Eu-Tb codoped tellurite glass are investigated. As the temperature increases from 7 to 300 K, both the PL intensity and the PL lifetime relative to the D-5(2)-> F-7(0) are nearly constant below 230 K and then an enhancement takes place. This anomalous feature is attributed to the thermally activated carrier transfer process from charged intrinsic defects states to Eu3+ energy levels. By co-doping tellurite glasses with Eu and Tb, a strong Eu3+ PL enhancement is shown due to excitation transfer from Tb3+ and intrinsic defects to Eu ions. (C) 2011 Elsevier B.V. All rights reserved.