Novel $\hbox{Eu}^{{2+}}$-Activated Glass Ceramics Precipitated With Green and Red Phosphors for High-Power White LED

We have obtained Eu
²⁺
-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-Ca
₂
SiO
₄
:Eu
²⁺
crystal phases with size of about 20-40 mum. After ceramization, Ca
₃
Si
₂
O
₇
:Eu
²⁺
crystals were also precipitated in addition to the beta-Ca
₂
SiO
₄
crystal. The photoluminescence had two broad emission bands: at 515 nm from Eu
²⁺
:beta-Ca
₂
SiO
₄
and at 600 nm from Eu
²⁺
:Ca
₃
Si
₂
O
₇
. 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. Eu
²⁺
-doped calcium silicate GC containing beta-Ca
₂
SiO
₄
and Ca
₃
Si
₂
O
₇
are suitable phosphor as the use of phosphor converting white LED with high color rendering.