Energy transfer induced Eu~3 photoluminescence enhancement in tellurite glass

摘要

In this work, structural, thermal and optical properties of Eu~3 doped TeO_2La_2O_3TiO_2 glass were investigated. The differential scanning calorimetry (DSC) measurements reveal an important stability factor ΔT=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 EuTb 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 ~5D_2→~7F_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 Eu~3 energy levels. By co-doping tellurite glasses with Eu and Tb, a strong Eu~3 PL enhancement is shown due to excitation transfer from Tb~3 and intrinsic defects to Eu ions.