Novel Eu2+-Activated Glass Ceramics Precipitated With Green and Red Phosphors for High-Power White LED

We have obtained Eu2+-doped glass-ceramic phosphors, where the two-phosphor crystals of green and red were precipitated by novel GC preparation frozen sorbet method and postceraming process. The as-made GC consisted of glass and spherical beta-Ca2SiO4:Eu2+ crystal phases with size of about 20-40 mu m. After ceramization, Ca3Si2O7:Eu2+ crystals were also precipitated in addition to the beta-Ca2SiO4 crystal. The photoluminescence had two broad emission bands: at 515 nm from Eu2+:beta-Ca2SiO4 and at 600 nm from Eu2+:Ca3Si2O7. Judging from the cathodoluminescence mapping images of microstructure, two emission bands peaked at 515 and 600 nm were observed from different parts in the GC. With increasing heat-treatment temperature, the color coordinates shifted from green range to center region, which corresponds to pure white in the International Commission on Illumination chromaticity diagram. Eu2+-doped calcium silicate GC containing beta-Ca2SiO4 and Ca3Si2O7 are suitable phosphor as the use of phosphor converting white LED with high color rendering.