Preparation, structure and luminescence properties of Ce3+ activated translucent glass ceramics containing garnet microcrystals

Glass ceramics containing Ce3+ doped garnet microcrystals were prepared from the spontaneous crystallization of SiO2-Al2O3-Y2O3-MgO-BaO-CeF3 glass melt. The formation of Ce3+:(Y,Mg)(3)(Al,Si)(5)O-12 grains in the glass matrix were investigated by X-ray diffraction, scanning electron microscope and photoluminescence spectra. The transmittance of samples improves with higher melting temperature or increasing BaO/MgO ratio, while the Ce3+: 5d -> 4f emission intensity weakens monotonously. Besides, the transmittance declines sharply after being heat treated above 950 degrees C, which is originated from the schistose BaAl2Si2O8 microcrystals in the glass matrix. The optimized sample with composition of 40SiO(2)-16Al(2)O(3)-8Y(2)O(3)-24BaO-12MgO-0.3CeF(3) was chosen to construct a white LED device, which yields bright white light with luminous efficiency of 23.6 lm/W, correlated color temperature of 5260 K and Ra of 85.5. It indicates that the investigated glass ceramics can be a promising color converter for white LEDs.