Enhanced upconverted luminescence and the optical thermometry behavior of Er3+-doped BaYbF5 transparent glass ceramics

Transparent SiO2 - Al2O3 - Na2O - CaO - BaF2 - YbF3 glass ceramics (GC) doped with Er3+ ions were successfully fabricated by a melt-quenching technique with subsequent heat treatment. The formation of BaYbF5 nano-crystalline phase was confirmed by X-ray diffraction and transmission electron microscopy. Compared to the precursor glass (PG), the clearer Stark splitting and greatly enhanced up-conversion (UC) emission in GC indicate that Er3+ ions mainly enter into BaYbF5 nanocrystals with low phonon energy after crystallization. The temperature dependent on purple UC emission ratio (which is due to the Er3+ 4G11/2→4I15/2 and 2H9/2→4I15/2 transitions) and common green UC emission ratio with low-power excitation in BaYbF5 GC have been studied respectively. In addition, the UC mechanisms in PG and GC are illustrated and analyzed. The outstanding properties of Er3+-doped BaYbF5 transparent GC may present potential applications in all-solid-state UC lasers and optical fiber temperature sensors.