Preparation and improved luminescent properties of Tb3+/Yb3+ co-doped Na2O–CaO–SiO2–Al2O3–ZnO–CaF2 transparent glass-ceramics

Transparent glass-ceramics containing CaF2 single-phase or CaF2/Ca5(PO4)3F two-phase were obtained by heat-treating the precursor glass. Compared with the precursor glass, the glass-ceramics containing CaF2 crystal with low phonon energy greatly enhance the emission intensity. Further research was conducted on the influence of various crystallization procedures on the luminescent properties of the glass-ceramic, and the procedure crystallized at 660 °C for 4 h was determined to be the optimal heat treatment. The SEM results indicate that the crystal size of the glass-ceramics is in the nanometer scale, which guarantees the possibility of its optical application. The three-photon absorption process of the Tb3+/Yb3+ co-doped glass-ceramics containing CaF2 single-phase was confirmed based on the up-conversion emission spectra excited at different power of 980 nm laser. The chromaticity coordinates of the Tb3+/Yb3+ co-doped glass-ceramic are located in the green region, indicating its potential applications in green lighting and other optical display devices.