Novel $\hbox {Eu}^{{2+}}$ -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 mum. 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.