Luminescence and long-lasting afterglow in Mn~(2+) and Eu co-doped ZnO-GeO2 glasses and glass ceramics prepared by sol-gel method

摘要

To develop new fluorescent and afterglow materials, Mn~(2+) and Eu~(3+) co-doped ZnO-GeO2 glasses and glass ceramics were prepared by a sol-gel method and their optical properties were investigated by measuring luminescence, excitation and afterglow spectra, and luminescence quantum yield (QY). Under UV irradiation at 254 nm, some glasses and all of the glass ceramics showed green luminescence peaking at 534 nm due to the ~4Ti → ~6A1 transition of tetrahedrally coordinated Mn~(2+) ions. The strongest luminescence was observed in a glass ceramic of 0.1MnO-0.3Eu2O3-25ZnO-75GeO2 heat treated at 900 °C, with QY of 49.8%. All of the green-luminescent glasses and glass ceramics showed green afterglow, and the afterglow lasting for more than 60 min was obtained in a glass ceramic heat treated at 900 °C. It is considered that the Eu~(3+) ions may behave as electron trapping centers to be associated with the occurrence of the green afterglow due to the Mn~(2+) ions in the co-doped system.