Guna Krieke

Near-Infrared-to-Blue Up-conversion Luminescence in Transparent Eu3+/Yb3+ Doped Oxyfluoride Phosphors

In this paper transparent glass ceramics co-doped with Eu and Yb ions has been synthesized by melt quenching and subsequent heat treatment of the precursor glass. X-ray diffraction and transmission electron microscopy studies show precipitation of distorted PbF2 crystallites in the glass ceramics. Excitation at 976 nm leads to the appearance of UCL (up-conversion luminescence) with the strong bands characteristic to Eu ions. Luminescence studies suggest that Eu emission appears as the result of cooperative excitation of Yb ions and subsequent energy transfer to europium ions. The presence of Er and Tm impurities, identified in the course of the experiment, leads to the white up-conversion emission of phosphors under the study.