Energy Transfer from Sn2+ to RE3+ Cations in ZnO–P2O5 Glass

The photoluminescence (PL) properties of rare earth (RE)-doped SnO–ZnO–P2O5 (RE-SZP) glass were examined in the visible region. RE-SZP glass, except for those doped with Ce3+, exhibited similar optical band edges because of the s–p transition in Sn2+. The RE3+ PL excitation bands in RE-SZP glass were red-shifted compared to the bands in Sn-free glass because of the energy transfer from the Sn2+ center. In addition, the emission intensity in a few RE-SZP glass systems was remarkably enhanced by Sn2+ addition. Emission decays of Sn2+ in the glass were typically independent of the RE3+, and suggest the exchange interaction between Sn2+ and RE3+. This indicated that the RE3+ cation is generally located close to the Sn2+ center in order to allow energy transfer.