Energy transfer and up-conversion luminescence in Er3+/Yb3+ co-doped transparent glass ceramic containing YF3 nano-crystals

Transparent glass ceramics containing YF3 nano-crystals were fabricated by heat treatment of the SiO2–Al2O3–NaF–YF3–LnF3 (Ln = Er, Yb) glasses. X-ray diffraction and transmission electron microscopy analyses evidenced the homogeneous distribution of spherical YF3 nano-crystals sized 25–30 nm among the glassy matrix. Energy dispersive X-ray spectroscopy measurement, combined with the Stark splitting of the absorption and emission bands, verified the incorporation of Er3+ and Yb3+ ions into YF3 nano-crystals. The infrared to visible up-conversion emission of Er3+ intensified with the increasing of Yb3+ concentration, ascribing to the increase of the efficiency of non-radiative energy transfer from Yb3+ to Er3+ which exceeded 45% for the 0.5Er3+/1.0Yb3+ co-doped sample. The up-conversion luminescence at 545 and 660 nm were affirmed coming from two-photon excitation process.