Enhanced visible emissions of Pr3+-doped oxyfluoride transparent glass-ceramics containing SrF2 nanocrystals

The Pr3+-doped oxyfluoride transparent glass and glass-ceramic (GC) with the composition of 41SiO2 + 10Al2O3 + 25.5LiF + 23SrF2 + 0.5Pr2O3 were prepared and investigated their optical and luminescence properties. The formation of SrF2 nanocrystals in GC has been confirmed by X-ray diffraction (XRD) and transmission electron micrographs (TEM). The Fourier transform infrared spectroscopy (FT-IR) studies were used to examine the network structure characteristics of silicates in the glass matrices. The XRD and TEM results suggest that the Pr3+ ions are progressively incorporated into the SrF2 nanocrystals in the GC with increase in time of thermal treatment at 650 °C, corresponding to the first crystallization temperature of the glass. The obtained visible emissions of Pr3+-doped GC are several times enhanced than that in the glass and the lifetime of the 3P0 level of the Pr3+ ions in glass and GC are found to be 7 and 12 μs, respectively. Therefore, the enhanced visible emission and lifetimes in GC are due to the incorporation of Pr3+ ions into the lower phonon energy of SrF2 nanocrystals in the GCs. Moreover, the smaller difference in ionic radius between the added trivalent ions (Pr3+) and Sr2+ induces the larger enhancement of luminescence intensity in the GC. Hence, these enhanced visible luminescence properties indicate that the present glass and GC could be useful for photonic device applications.